/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License, Version 1.0 only * (the "License"). You may not use this file except in compliance * with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */ /* All Rights Reserved */ /* * Portions of this source code were derived from Berkeley 4.3 BSD * under license from the Regents of the University of California. */ #pragma ident "%Z%%M% %I% %E% SMI" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define NPHLOCKS 64 /* Number of locks; must be power of 2 */ #define PHLOCKADDR(php) &plocks[(((uintptr_t)(php)) >> 8) & (NPHLOCKS - 1)] #define PHLOCK(php) PHLOCKADDR(php).pp_lock #define PH_ENTER(php) mutex_enter(PHLOCK(php)) #define PH_EXIT(php) mutex_exit(PHLOCK(php)) #define VALID_POLL_EVENTS (POLLIN | POLLPRI | POLLOUT | POLLRDNORM \ | POLLRDBAND | POLLWRBAND | POLLHUP | POLLERR | POLLNVAL) /* * global counters to collect some stats */ static struct { kstat_named_t polllistmiss; /* failed to find a cached poll list */ kstat_named_t pollcachehit; /* list matched 100% w/ cached one */ kstat_named_t pollcachephit; /* list matched < 100% w/ cached one */ kstat_named_t pollcachemiss; /* every list entry is dif from cache */ } pollstats = { { "polllistmiss", KSTAT_DATA_UINT64 }, { "pollcachehit", KSTAT_DATA_UINT64 }, { "pollcachephit", KSTAT_DATA_UINT64 }, { "pollcachemiss", KSTAT_DATA_UINT64 } }; kstat_named_t *pollstats_ptr = (kstat_named_t *)&pollstats; uint_t pollstats_ndata = sizeof (pollstats) / sizeof (kstat_named_t); struct pplock { kmutex_t pp_lock; short pp_flag; kcondvar_t pp_wait_cv; int32_t pp_pad; /* to a nice round 16 bytes */ }; static struct pplock plocks[NPHLOCKS]; /* Hash array of pollhead locks */ #ifdef DEBUG static int pollchecksanity(pollstate_t *, nfds_t); static int pollcheckxref(pollstate_t *, int); static void pollcheckphlist(void); static int pollcheckrevents(pollstate_t *, int, int, int); static void checkpolldat(pollstate_t *); #endif /* DEBUG */ static int plist_chkdupfd(file_t *, polldat_t *, pollstate_t *, pollfd_t *, int, int *); /* * Data structure overview: * The per-thread poll state consists of * one pollstate_t * one pollcache_t * one bitmap with one event bit per fd * a (two-dimensional) hashed array of polldat_t structures - one entry * per fd * * This conglomerate of data structures interact with * the pollhead which is used by VOP_POLL and pollwakeup * (protected by the PHLOCK, cached array of plocks), and * the fpollinfo list hanging off the fi_list which is used to notify * poll when a cached fd is closed. This is protected by uf_lock. * * Invariants: * pd_php (pollhead pointer) is set iff (if and only if) the polldat * is on that pollhead. This is modified atomically under pc_lock. * * pd_fp (file_t pointer) is set iff the thread is on the fpollinfo * list for that open file. * This is modified atomically under pc_lock. * * pd_count is the sum (over all values of i) of pd_ref[i].xf_refcnt. * Iff pd_ref[i].xf_refcnt >= 1 then * ps_pcacheset[i].pcs_pollfd[pd_ref[i].xf_position].fd == pd_fd * Iff pd_ref[i].xf_refcnt > 1 then * In ps_pcacheset[i].pcs_pollfd between index * pd_ref[i].xf_position] and the end of the list * there are xf_refcnt entries with .fd == pd_fd * * Locking design: * Whenever possible the design relies on the fact that the poll cache state * is per thread thus for both poll and exit it is self-synchronizing. * Thus the key interactions where other threads access the state are: * pollwakeup (and polltime), and * close cleaning up the cached references to an open file * * The two key locks in poll proper is ps_lock and pc_lock. * * The ps_lock is used for synchronization between poll, (lwp_)exit and close * to ensure that modifications to pollcacheset structure are serialized. * This lock is held through most of poll() except where poll sleeps * since there is little need to handle closes concurrently with the execution * of poll. * The pc_lock protects most of the fields in pollcache structure and polldat * structures (which are accessed by poll, pollwakeup, and polltime) * with the exception of fields that are only modified when only one thread * can access this per-thread state. * Those exceptions occur in poll when first allocating the per-thread state, * when poll grows the number of polldat (never shrinks), and when * exit/pollcleanup has ensured that there are no references from either * pollheads or fpollinfo to the threads poll state. * * Poll(2) system call is the only path which ps_lock and pc_lock are both * held, in that order. It needs ps_lock to synchronize with close and * lwp_exit; and pc_lock with pollwakeup. * * The locking interaction between pc_lock and PHLOCK take into account * that poll acquires these locks in the order of pc_lock and then PHLOCK * while pollwakeup does it in the reverse order. Thus pollwakeup implements * deadlock avoidance by dropping the locks and reacquiring them in the * reverse order. For this to work pollwakeup needs to prevent the thread * from exiting and freeing all of the poll related state. Thus is done * using * the pc_no_exit lock * the pc_busy counter * the pc_busy_cv condition variable * * The locking interaction between pc_lock and uf_lock has similar * issues. Poll holds ps_lock and/or pc_lock across calls to getf/releasef * which acquire uf_lock. The poll cleanup in close needs to hold uf_lock * to prevent poll or exit from doing a delfpollinfo after which the thread * might exit. But the cleanup needs to acquire pc_lock when modifying * the poll cache state. The solution is to use pc_busy and do the close * cleanup in two phases: * First close calls pollblockexit which increments pc_busy. * This prevents the per-thread poll related state from being freed. * Then close drops uf_lock and calls pollcacheclean. * This routine can then acquire pc_lock and remove any references * to the closing fd (as well as recording that it has been closed * so that a POLLNVAL can be generated even if the fd is reused before * poll has been woken up and checked getf() again). * * When removing a polled fd from poll cache, the fd is always removed * from pollhead list first and then from fpollinfo list, i.e., * pollhead_delete() is called before delfpollinfo(). * * * Locking hierarchy: * pc_no_exit is a leaf level lock. * ps_lock is held when acquiring pc_lock (except when pollwakeup * acquires pc_lock). * pc_lock might be held when acquiring PHLOCK (pollhead_insert/ * pollhead_delete) * pc_lock is always held (but this is not required) * when acquiring PHLOCK (in polladd/pollhead_delete and pollwakeup called * from pcache_clean_entry). * pc_lock is held across addfpollinfo/delfpollinfo which acquire * uf_lock. * pc_lock is held across getf/releasef which acquire uf_lock. * ps_lock might be held across getf/releasef which acquire uf_lock. * pollwakeup tries to acquire pc_lock while holding PHLOCK * but drops the locks and reacquire them in reverse order to avoid * deadlock. * * Note also that there is deadlock avoidance support for VOP_POLL routines * and pollwakeup involving a file system or driver lock. * See below. */ /* * Deadlock avoidance support for VOP_POLL() routines. This is * sometimes necessary to prevent deadlock between polling threads * (which hold poll locks on entry to xx_poll(), then acquire foo) * and pollwakeup() threads (which hold foo, then acquire poll locks). * * pollunlock(void) releases whatever poll locks the current thread holds, * returning a cookie for use by pollrelock(); * * pollrelock(cookie) reacquires previously dropped poll locks; * * polllock(php, mutex) does the common case: pollunlock(), * acquire the problematic mutex, pollrelock(). */ int pollunlock(void) { pollcache_t *pcp; int lockstate = 0; /* * t_pollcache is set by /dev/poll and event ports (port_fd.c). * If the pollrelock/pollunlock is called as a result of poll(2), * the t_pollcache should be NULL. */ if (curthread->t_pollcache == NULL) pcp = curthread->t_pollstate->ps_pcache; else pcp = curthread->t_pollcache; if (mutex_owned(&pcp->pc_lock)) { lockstate = 1; mutex_exit(&pcp->pc_lock); } return (lockstate); } void pollrelock(int lockstate) { pollcache_t *pcp; /* * t_pollcache is set by /dev/poll and event ports (port_fd.c). * If the pollrelock/pollunlock is called as a result of poll(2), * the t_pollcache should be NULL. */ if (curthread->t_pollcache == NULL) pcp = curthread->t_pollstate->ps_pcache; else pcp = curthread->t_pollcache; if (lockstate > 0) mutex_enter(&pcp->pc_lock); } /* ARGSUSED */ void polllock(pollhead_t *php, kmutex_t *lp) { if (!mutex_tryenter(lp)) { int lockstate = pollunlock(); mutex_enter(lp); pollrelock(lockstate); } } static int poll_common(pollfd_t *fds, nfds_t nfds, timespec_t *tsp, k_sigset_t *ksetp) { kthread_t *t = curthread; klwp_t *lwp = ttolwp(t); proc_t *p = ttoproc(t); int fdcnt = 0; int rval; int i; timespec_t *rqtp = NULL; int timecheck = 0; int imm_timeout = 0; pollfd_t *pollfdp; pollstate_t *ps; pollcache_t *pcp; int error = 0; nfds_t old_nfds; int cacheindex = 0; /* which cache set is used */ /* * Determine the precise future time of the requested timeout, if any. */ if (tsp != NULL) { if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) imm_timeout = 1; else { timespec_t now; timecheck = timechanged; gethrestime(&now); rqtp = tsp; timespecadd(rqtp, &now); } } /* * Reset our signal mask, if requested. */ if (ksetp != NULL) { mutex_enter(&p->p_lock); schedctl_finish_sigblock(t); lwp->lwp_sigoldmask = t->t_hold; t->t_hold = *ksetp; t->t_flag |= T_TOMASK; /* * Call cv_timedwait_sig() just to check for signals. * We will return immediately with either 0 or -1. */ if (!cv_timedwait_sig(&t->t_delay_cv, &p->p_lock, lbolt)) { mutex_exit(&p->p_lock); error = EINTR; goto pollout; } mutex_exit(&p->p_lock); } /* * Check to see if this guy just wants to use poll() as a timeout. * If yes then bypass all the other stuff and make him sleep. */ if (nfds == 0) { /* * Sleep until we have passed the requested future * time or until interrupted by a signal. * Do not check for signals if we have a zero timeout. */ if (!imm_timeout) { mutex_enter(&t->t_delay_lock); while ((rval = cv_waituntil_sig(&t->t_delay_cv, &t->t_delay_lock, rqtp, timecheck)) > 0) continue; mutex_exit(&t->t_delay_lock); if (rval == 0) error = EINTR; } goto pollout; } if (nfds > p->p_fno_ctl) { mutex_enter(&p->p_lock); (void) rctl_action(rctlproc_legacy[RLIMIT_NOFILE], p->p_rctls, p, RCA_SAFE); mutex_exit(&p->p_lock); error = EINVAL; goto pollout; } /* * Need to allocate memory for pollstate before anything because * the mutex and cv are created in this space */ if ((ps = t->t_pollstate) == NULL) { t->t_pollstate = pollstate_create(); ps = t->t_pollstate; } if (ps->ps_pcache == NULL) ps->ps_pcache = pcache_alloc(); pcp = ps->ps_pcache; /* * NOTE: for performance, buffers are saved across poll() calls. * The theory is that if a process polls heavily, it tends to poll * on the same set of descriptors. Therefore, we only reallocate * buffers when nfds changes. There is no hysteresis control, * because there is no data to suggest that this is necessary; * the penalty of reallocating is not *that* great in any event. */ old_nfds = ps->ps_nfds; if (nfds != old_nfds) { kmem_free(ps->ps_pollfd, old_nfds * sizeof (pollfd_t)); pollfdp = kmem_alloc(nfds * sizeof (pollfd_t), KM_SLEEP); ps->ps_pollfd = pollfdp; ps->ps_nfds = nfds; } pollfdp = ps->ps_pollfd; if (copyin(fds, pollfdp, nfds * sizeof (pollfd_t))) { error = EFAULT; goto pollout; } if (fds == NULL) { /* * If the process has page 0 mapped, then the copyin() above * will succeed even if fds is NULL. However, our cached * poll lists are keyed by the address of the passed-in fds * structure, and we use the value NULL to indicate an unused * poll cache list entry. As such, we elect not to support * NULL as a valid (user) memory address and fail the poll() * call. */ error = EINVAL; goto pollout; } /* * If this thread polls for the first time, allocate ALL poll * cache data structures and cache the poll fd list. This * allocation is delayed till now because lwp's polling 0 fd * (i.e. using poll as timeout()) don't need this memory. */ mutex_enter(&ps->ps_lock); pcp = ps->ps_pcache; ASSERT(pcp != NULL); if (pcp->pc_bitmap == NULL) { pcache_create(pcp, nfds); /* * poll and cache this poll fd list in ps_pcacheset[0]. */ error = pcacheset_cache_list(ps, fds, &fdcnt, cacheindex); if (fdcnt || error) { mutex_exit(&ps->ps_lock); goto pollout; } } else { pollcacheset_t *pcset = ps->ps_pcacheset; /* * Not first time polling. Select a cached poll list by * matching user pollfd list buffer address. */ for (cacheindex = 0; cacheindex < ps->ps_nsets; cacheindex++) { if (pcset[cacheindex].pcs_usradr == (uintptr_t)fds) { if ((++pcset[cacheindex].pcs_count) == 0) { /* * counter is wrapping around. */ pcacheset_reset_count(ps, cacheindex); } /* * examine and resolve possible * difference of the current poll * list and previously cached one. * If there is an error during resolve(), * the callee will guarantee the consistency * of cached poll list and cache content. */ error = pcacheset_resolve(ps, nfds, &fdcnt, cacheindex); if (error) { mutex_exit(&ps->ps_lock); goto pollout; } break; } /* * Note that pcs_usradr field of an used entry won't be * NULL because it stores the address of passed-in fds, * and NULL fds will not be cached (Then it is either * the special timeout case when nfds is 0 or it returns * failure directly). */ if (pcset[cacheindex].pcs_usradr == NULL) { /* * found an unused entry. Use it to cache * this poll list. */ error = pcacheset_cache_list(ps, fds, &fdcnt, cacheindex); if (fdcnt || error) { mutex_exit(&ps->ps_lock); goto pollout; } break; } } if (cacheindex == ps->ps_nsets) { /* * We failed to find a matching cached poll fd list. * replace an old list. */ pollstats.polllistmiss.value.ui64++; cacheindex = pcacheset_replace(ps); ASSERT(cacheindex < ps->ps_nsets); pcset[cacheindex].pcs_usradr = (uintptr_t)fds; error = pcacheset_resolve(ps, nfds, &fdcnt, cacheindex); if (error) { mutex_exit(&ps->ps_lock); goto pollout; } } } /* * Always scan the bitmap with the lock on the pollcache held. * This is to make sure that a wakeup does not come undetected. * If the lock is not held, a pollwakeup could have come for an * fd we already checked but before this thread sleeps, in which * case the wakeup is missed. Now we hold the pcache lock and * check the bitmap again. This will prevent wakeup from happening * while we hold pcache lock since pollwakeup() will also lock * the pcache before updating poll bitmap. */ mutex_enter(&pcp->pc_lock); for (;;) { pcp->pc_flag = 0; error = pcache_poll(pollfdp, ps, nfds, &fdcnt, cacheindex); if (fdcnt || error) { mutex_exit(&pcp->pc_lock); mutex_exit(&ps->ps_lock); break; } /* * If T_POLLWAKE is set, a pollwakeup() was performed on * one of the file descriptors. This can happen only if * one of the VOP_POLL() functions dropped pcp->pc_lock. * The only current cases of this is in procfs (prpoll()) * and STREAMS (strpoll()). */ if (pcp->pc_flag & T_POLLWAKE) continue; /* * If you get here, the poll of fds was unsuccessful. * Wait until some fd becomes readable, writable, or gets * an exception, or until a signal or a timeout occurs. * Do not check for signals if we have a zero timeout. */ mutex_exit(&ps->ps_lock); if (imm_timeout) rval = -1; else rval = cv_waituntil_sig(&pcp->pc_cv, &pcp->pc_lock, rqtp, timecheck); mutex_exit(&pcp->pc_lock); /* * If we have received a signal or timed out * then break out and return. */ if (rval <= 0) { if (rval == 0) error = EINTR; break; } /* * We have not received a signal or timed out. * Continue around and poll fds again. */ mutex_enter(&ps->ps_lock); mutex_enter(&pcp->pc_lock); } pollout: /* * If we changed the signal mask but we received * no signal then restore the signal mask. * Otherwise psig() will deal with the signal mask. */ if (ksetp != NULL) { mutex_enter(&p->p_lock); if (lwp->lwp_cursig == 0) { t->t_hold = lwp->lwp_sigoldmask; t->t_flag &= ~T_TOMASK; } mutex_exit(&p->p_lock); } if (error) return (set_errno(error)); /* * Copy out the events and return the fdcnt to the user. */ if (nfds != 0 && copyout(pollfdp, fds, nfds * sizeof (pollfd_t))) return (set_errno(EFAULT)); #ifdef DEBUG /* * Another sanity check: */ if (fdcnt) { int reventcnt = 0; for (i = 0; i < nfds; i++) { if (pollfdp[i].fd < 0) { ASSERT(pollfdp[i].revents == 0); continue; } if (pollfdp[i].revents) { reventcnt++; } } ASSERT(fdcnt == reventcnt); } else { for (i = 0; i < nfds; i++) { ASSERT(pollfdp[i].revents == 0); } } #endif /* DEBUG */ return (fdcnt); } /* * This system call trap exists solely for binary compatibility with * old statically-linked applications. It is not called from libc. * It should be removed in the next release. */ int poll(pollfd_t *fds, nfds_t nfds, int time_out) { timespec_t ts; timespec_t *tsp; if (time_out < 0) tsp = NULL; else { ts.tv_sec = time_out / MILLISEC; ts.tv_nsec = (time_out % MILLISEC) * MICROSEC; tsp = &ts; } return (poll_common(fds, nfds, tsp, NULL)); } /* * This is the system call trap that poll(), * select() and pselect() are built upon. * It is a private interface between libc and the kernel. */ int pollsys(pollfd_t *fds, nfds_t nfds, timespec_t *timeoutp, sigset_t *setp) { timespec_t ts; timespec_t *tsp; sigset_t set; k_sigset_t kset; k_sigset_t *ksetp; model_t datamodel = get_udatamodel(); if (timeoutp == NULL) tsp = NULL; else { if (datamodel == DATAMODEL_NATIVE) { if (copyin(timeoutp, &ts, sizeof (ts))) return (set_errno(EFAULT)); } else { timespec32_t ts32; if (copyin(timeoutp, &ts32, sizeof (ts32))) return (set_errno(EFAULT)); TIMESPEC32_TO_TIMESPEC(&ts, &ts32) } if (itimerspecfix(&ts)) return (set_errno(EINVAL)); tsp = &ts; } if (setp == NULL) ksetp = NULL; else { if (copyin(setp, &set, sizeof (set))) return (set_errno(EFAULT)); sigutok(&set, &kset); ksetp = &kset; } return (poll_common(fds, nfds, tsp, ksetp)); } /* * Clean up any state left around by poll(2). Called when a thread exits. */ void pollcleanup() { pollstate_t *ps = curthread->t_pollstate; pollcache_t *pcp; if (ps == NULL) return; pcp = ps->ps_pcache; /* * free up all cached poll fds */ if (pcp == NULL) { /* this pollstate is used by /dev/poll */ goto pollcleanout; } if (pcp->pc_bitmap != NULL) { ASSERT(MUTEX_NOT_HELD(&ps->ps_lock)); /* * a close lwp can race with us when cleaning up a polldat * entry. We hold the ps_lock when cleaning hash table. * Since this pollcache is going away anyway, there is no * need to hold the pc_lock. */ mutex_enter(&ps->ps_lock); pcache_clean(pcp); mutex_exit(&ps->ps_lock); #ifdef DEBUG /* * At this point, all fds cached by this lwp should be * cleaned up. There should be no fd in fi_list still * reference this thread. */ checkfpollinfo(); /* sanity check */ pollcheckphlist(); /* sanity check */ #endif /* DEBUG */ } /* * Be sure no one is referencing thread before exiting */ mutex_enter(&pcp->pc_no_exit); ASSERT(pcp->pc_busy >= 0); while (pcp->pc_busy > 0) cv_wait(&pcp->pc_busy_cv, &pcp->pc_no_exit); mutex_exit(&pcp->pc_no_exit); pollcleanout: pollstate_destroy(ps); curthread->t_pollstate = NULL; } /* * pollwakeup() - poke threads waiting in poll() for some event * on a particular object. * * The threads hanging off of the specified pollhead structure are scanned. * If their event mask matches the specified event(s), then pollnotify() is * called to poke the thread. * * Multiple events may be specified. When POLLHUP or POLLERR are specified, * all waiting threads are poked. * * It is important that pollnotify() not drop the lock protecting the list * of threads. */ void pollwakeup(pollhead_t *php, short events_arg) { polldat_t *pdp; int events = (ushort_t)events_arg; retry: PH_ENTER(php); /* * About half of all pollwakeups don't do anything, because the * pollhead list is empty (i.e, nobody is interested in the event). * For this common case, we can optimize out locking overhead. */ if (php->ph_list == NULL) { PH_EXIT(php); return; } for (pdp = php->ph_list; pdp; pdp = pdp->pd_next) { if ((pdp->pd_events & events) || (events & (POLLHUP | POLLERR))) { pollcache_t *pcp; if (pdp->pd_portev != NULL) { port_kevent_t *pkevp = pdp->pd_portev; /* * Object (fd) is associated with an event port, * => send event notification to the port. */ pkevp->portkev_events |= events & (pdp->pd_events | POLLHUP | POLLERR); if (pkevp->portkev_flags & PORT_KEV_VALID) { pkevp->portkev_flags &= ~PORT_KEV_VALID; (void) port_send_event(pdp->pd_portev); } continue; } pcp = pdp->pd_pcache; /* * Try to grab the lock for this thread. If * we don't get it then we may deadlock so * back out and restart all over again. Note * that the failure rate is very very low. */ if (mutex_tryenter(&pcp->pc_lock)) { pollnotify(pcp, pdp->pd_fd); mutex_exit(&pcp->pc_lock); } else { /* * We are here because: * 1) This thread has been woke up * and is trying to get out of poll(). * 2) Some other thread is also here * but with a different pollhead lock. * * So, we need to drop the lock on pollhead * because of (1) but we want to prevent * that thread from doing lwp_exit() or * devpoll close. We want to ensure that * the pollcache pointer is still invalid. * * Solution: Grab the pcp->pc_no_exit lock, * increment the pc_busy counter, drop every * lock in sight. Get out of the way and wait * for type (2) threads to finish. */ mutex_enter(&pcp->pc_no_exit); pcp->pc_busy++; /* prevents exit()'s */ mutex_exit(&pcp->pc_no_exit); PH_EXIT(php); mutex_enter(&pcp->pc_lock); mutex_exit(&pcp->pc_lock); mutex_enter(&pcp->pc_no_exit); pcp->pc_busy--; if (pcp->pc_busy == 0) { /* * Wakeup the thread waiting in * thread_exit(). */ cv_signal(&pcp->pc_busy_cv); } mutex_exit(&pcp->pc_no_exit); goto retry; } } } PH_EXIT(php); } /* * This function is called to inform a thread that * an event being polled for has occurred. * The pollstate lock on the thread should be held on entry. */ void pollnotify(pollcache_t *pcp, int fd) { ASSERT(fd < pcp->pc_mapsize); ASSERT(MUTEX_HELD(&pcp->pc_lock)); BT_SET(pcp->pc_bitmap, fd); pcp->pc_flag |= T_POLLWAKE; cv_signal(&pcp->pc_cv); } /* * add a polldat entry to pollhead ph_list. The polldat struct is used * by pollwakeup to wake sleeping pollers when polled events has happened. */ void pollhead_insert(pollhead_t *php, polldat_t *pdp) { PH_ENTER(php); ASSERT(pdp->pd_next == NULL); #ifdef DEBUG { /* * the polldat should not be already on the list */ polldat_t *wp; for (wp = php->ph_list; wp; wp = wp->pd_next) { ASSERT(wp != pdp); } } #endif /* DEBUG */ pdp->pd_next = php->ph_list; php->ph_list = pdp; PH_EXIT(php); } /* * Delete the polldat entry from ph_list. */ void pollhead_delete(pollhead_t *php, polldat_t *pdp) { polldat_t *wp; polldat_t **wpp; PH_ENTER(php); for (wpp = &php->ph_list; (wp = *wpp) != NULL; wpp = &wp->pd_next) { if (wp == pdp) { *wpp = pdp->pd_next; pdp->pd_next = NULL; break; } } #ifdef DEBUG /* assert that pdp is no longer in the list */ for (wp = *wpp; wp; wp = wp->pd_next) { ASSERT(wp != pdp); } #endif /* DEBUG */ PH_EXIT(php); } /* * walk through the poll fd lists to see if they are identical. This is an * expensive operation and should not be done more than once for each poll() * call. * * As an optimization (i.e., not having to go through the lists more than * once), this routine also clear the revents field of pollfd in 'current'. * Zeroing out the revents field of each entry in current poll list is * required by poll man page. * * Since the events field of cached list has illegal poll events filtered * out, the current list applies the same filtering before comparison. * * The routine stops when it detects a meaningful difference, or when it * exhausts the lists. */ int pcacheset_cmp(pollfd_t *current, pollfd_t *cached, pollfd_t *newlist, int n) { int ix; for (ix = 0; ix < n; ix++) { if (current[ix].fd == cached[ix].fd) { /* * Filter out invalid poll events while we are in * inside the loop. */ if (current[ix].events & ~VALID_POLL_EVENTS) { current[ix].events &= VALID_POLL_EVENTS; if (newlist != NULL) newlist[ix].events = current[ix].events; } if (current[ix].events == cached[ix].events) { current[ix].revents = 0; continue; } } if ((current[ix].fd < 0) && (cached[ix].fd < 0)) { current[ix].revents = 0; continue; } return (ix); } return (ix); } /* * This routine returns a pointer to a cached poll fd entry, or NULL if it * does not find it in the hash table. */ polldat_t * pcache_lookup_fd(pollcache_t *pcp, int fd) { int hashindex; polldat_t *pdp; hashindex = POLLHASH(pcp->pc_hashsize, fd); pdp = pcp->pc_hash[hashindex]; while (pdp != NULL) { if (pdp->pd_fd == fd) break; pdp = pdp->pd_hashnext; } return (pdp); } polldat_t * pcache_alloc_fd(int nsets) { polldat_t *pdp; pdp = kmem_zalloc(sizeof (polldat_t), KM_SLEEP); if (nsets > 0) { pdp->pd_ref = kmem_zalloc(sizeof (xref_t) * nsets, KM_SLEEP); pdp->pd_nsets = nsets; } return (pdp); } /* * This routine inserts a polldat into the pollcache's hash table. It * may be necessary to grow the size of the hash table. */ void pcache_insert_fd(pollcache_t *pcp, polldat_t *pdp, nfds_t nfds) { int hashindex; int fd; if ((pcp->pc_fdcount > pcp->pc_hashsize * POLLHASHTHRESHOLD) || (nfds > pcp->pc_hashsize * POLLHASHTHRESHOLD)) { pcache_grow_hashtbl(pcp, nfds); } fd = pdp->pd_fd; hashindex = POLLHASH(pcp->pc_hashsize, fd); pdp->pd_hashnext = pcp->pc_hash[hashindex]; pcp->pc_hash[hashindex] = pdp; pcp->pc_fdcount++; #ifdef DEBUG { /* * same fd should not appear on a hash list twice */ polldat_t *pdp1; for (pdp1 = pdp->pd_hashnext; pdp1; pdp1 = pdp1->pd_hashnext) { ASSERT(pdp->pd_fd != pdp1->pd_fd); } } #endif /* DEBUG */ } /* * Grow the hash table -- either double the table size or round it to the * nearest multiples of POLLHASHCHUNKSZ, whichever is bigger. Rehash all the * elements on the hash table. */ void pcache_grow_hashtbl(pollcache_t *pcp, nfds_t nfds) { int oldsize; polldat_t **oldtbl; polldat_t *pdp, *pdp1; int i; #ifdef DEBUG int count = 0; #endif ASSERT(pcp->pc_hashsize % POLLHASHCHUNKSZ == 0); oldsize = pcp->pc_hashsize; oldtbl = pcp->pc_hash; if (nfds > pcp->pc_hashsize * POLLHASHINC) { pcp->pc_hashsize = (nfds + POLLHASHCHUNKSZ - 1) & ~(POLLHASHCHUNKSZ - 1); } else { pcp->pc_hashsize = pcp->pc_hashsize * POLLHASHINC; } pcp->pc_hash = kmem_zalloc(pcp->pc_hashsize * sizeof (polldat_t *), KM_SLEEP); /* * rehash existing elements */ pcp->pc_fdcount = 0; for (i = 0; i < oldsize; i++) { pdp = oldtbl[i]; while (pdp != NULL) { pdp1 = pdp->pd_hashnext; pcache_insert_fd(pcp, pdp, nfds); pdp = pdp1; #ifdef DEBUG count++; #endif } } kmem_free(oldtbl, oldsize * sizeof (polldat_t *)); ASSERT(pcp->pc_fdcount == count); } void pcache_grow_map(pollcache_t *pcp, int fd) { int newsize; ulong_t *newmap; /* * grow to nearest multiple of POLLMAPCHUNK, assuming POLLMAPCHUNK is * power of 2. */ newsize = (fd + POLLMAPCHUNK) & ~(POLLMAPCHUNK - 1); newmap = kmem_zalloc((newsize / BT_NBIPUL) * sizeof (ulong_t), KM_SLEEP); /* * don't want pollwakeup to set a bit while growing the bitmap. */ ASSERT(mutex_owned(&pcp->pc_lock) == 0); mutex_enter(&pcp->pc_lock); bcopy(pcp->pc_bitmap, newmap, (pcp->pc_mapsize / BT_NBIPUL) * sizeof (ulong_t)); kmem_free(pcp->pc_bitmap, (pcp->pc_mapsize /BT_NBIPUL) * sizeof (ulong_t)); pcp->pc_bitmap = newmap; pcp->pc_mapsize = newsize; mutex_exit(&pcp->pc_lock); } /* * remove all the reference from pollhead list and fpollinfo lists. */ void pcache_clean(pollcache_t *pcp) { int i; polldat_t **hashtbl; polldat_t *pdp; ASSERT(MUTEX_HELD(&curthread->t_pollstate->ps_lock)); hashtbl = pcp->pc_hash; for (i = 0; i < pcp->pc_hashsize; i++) { for (pdp = hashtbl[i]; pdp; pdp = pdp->pd_hashnext) { if (pdp->pd_php != NULL) { pollhead_delete(pdp->pd_php, pdp); pdp->pd_php = NULL; } if (pdp->pd_fp != NULL) { delfpollinfo(pdp->pd_fd); pdp->pd_fp = NULL; } } } } void pcacheset_invalidate(pollstate_t *ps, polldat_t *pdp) { int i; int fd = pdp->pd_fd; /* * we come here because an earlier close() on this cached poll fd. */ ASSERT(pdp->pd_fp == NULL); ASSERT(MUTEX_HELD(&ps->ps_lock)); pdp->pd_events = 0; for (i = 0; i < ps->ps_nsets; i++) { xref_t *refp; pollcacheset_t *pcsp; ASSERT(pdp->pd_ref != NULL); refp = &pdp->pd_ref[i]; if (refp->xf_refcnt) { ASSERT(refp->xf_position >= 0); pcsp = &ps->ps_pcacheset[i]; if (refp->xf_refcnt == 1) { pcsp->pcs_pollfd[refp->xf_position].fd = -1; refp->xf_refcnt = 0; pdp->pd_count--; } else if (refp->xf_refcnt > 1) { int j; /* * turn off every appearance in pcs_pollfd list */ for (j = refp->xf_position; j < pcsp->pcs_nfds; j++) { if (pcsp->pcs_pollfd[j].fd == fd) { pcsp->pcs_pollfd[j].fd = -1; refp->xf_refcnt--; pdp->pd_count--; } } } ASSERT(refp->xf_refcnt == 0); refp->xf_position = POLLPOSINVAL; } } ASSERT(pdp->pd_count == 0); } /* * Insert poll fd into the pollcache, and add poll registration. * This routine is called after getf() and before releasef(). So the vnode * can not disappear even if we block here. * If there is an error, the polled fd is not cached. */ int pcache_insert(pollstate_t *ps, file_t *fp, pollfd_t *pollfdp, int *fdcntp, ssize_t pos, int which) { pollcache_t *pcp = ps->ps_pcache; polldat_t *pdp; int error; int fd; pollhead_t *memphp = NULL; xref_t *refp; int newpollfd = 0; ASSERT(MUTEX_HELD(&ps->ps_lock)); /* * The poll caching uses the existing VOP_POLL interface. If there * is no polled events, we want the polled device to set its "some * one is sleeping in poll" flag. When the polled events happen * later, the driver will call pollwakeup(). We achieve this by * always passing 0 in the third parameter ("anyyet") when calling * VOP_POLL. This parameter is not looked at by drivers when the * polled events exist. If a driver chooses to ignore this parameter * and call pollwakeup whenever the polled events happen, that will * be OK too. */ ASSERT(curthread->t_pollcache == NULL); error = VOP_POLL(fp->f_vnode, pollfdp->events, 0, &pollfdp->revents, &memphp); if (error) { return (error); } if (pollfdp->revents) { (*fdcntp)++; } /* * polling the underlying device succeeded. Now we can cache it. * A close can't come in here because we have not done a releasef() * yet. */ fd = pollfdp->fd; pdp = pcache_lookup_fd(pcp, fd); if (pdp == NULL) { ASSERT(ps->ps_nsets > 0); pdp = pcache_alloc_fd(ps->ps_nsets); newpollfd = 1; } /* * If this entry was used to cache a poll fd which was closed, and * this entry has not been cleaned, do it now. */ if ((pdp->pd_count > 0) && (pdp->pd_fp == NULL)) { pcacheset_invalidate(ps, pdp); ASSERT(pdp->pd_next == NULL); } if (pdp->pd_count == 0) { pdp->pd_fd = fd; pdp->pd_fp = fp; addfpollinfo(fd); pdp->pd_thread = curthread; pdp->pd_pcache = pcp; /* * the entry is never used or cleared by removing a cached * pollfd (pcache_delete_fd). So all the fields should be clear. */ ASSERT(pdp->pd_next == NULL); } /* * A polled fd is considered cached. So there should be a fpollinfo * entry on uf_fpollinfo list. */ ASSERT(infpollinfo(fd)); /* * If there is an inconsistency, we want to know it here. */ ASSERT(pdp->pd_fp == fp); /* * XXX pd_events is a union of all polled events on this fd, possibly * by different threads. Unless this is a new first poll(), pd_events * never shrinks. If an event is no longer polled by a process, there * is no way to cancel that event. In that case, poll degrade to its * old form -- polling on this fd every time poll() is called. The * assumption is an app always polls the same type of events. */ pdp->pd_events |= pollfdp->events; pdp->pd_count++; /* * There is not much special handling for multiple appearances of * same fd other than xf_position always recording the first * appearance in poll list. If this is called from pcacheset_cache_list, * a VOP_POLL is called on every pollfd entry; therefore each * revents and fdcnt should be set correctly. If this is called from * pcacheset_resolve, we don't care about fdcnt here. Pollreadmap will * pick up the right count and handle revents field of each pollfd * entry. */ ASSERT(pdp->pd_ref != NULL); refp = &pdp->pd_ref[which]; if (refp->xf_refcnt == 0) { refp->xf_position = pos; } else { /* * xf_position records the fd's first appearance in poll list */ if (pos < refp->xf_position) { refp->xf_position = pos; } } ASSERT(pollfdp->fd == ps->ps_pollfd[refp->xf_position].fd); refp->xf_refcnt++; if (fd >= pcp->pc_mapsize) { pcache_grow_map(pcp, fd); } if (fd > pcp->pc_mapend) { pcp->pc_mapend = fd; } if (newpollfd != 0) { pcache_insert_fd(ps->ps_pcache, pdp, ps->ps_nfds); } if (memphp) { if (pdp->pd_php == NULL) { pollhead_insert(memphp, pdp); pdp->pd_php = memphp; } else { if (memphp != pdp->pd_php) { /* * layered devices (e.g. console driver) * may change the vnode and thus the pollhead * pointer out from underneath us. */ pollhead_delete(pdp->pd_php, pdp); pollhead_insert(memphp, pdp); pdp->pd_php = memphp; } } } /* * Since there is a considerable window between VOP_POLL and when * we actually put the polldat struct on the pollhead list, we could * miss a pollwakeup. In the case of polling additional events, we * don't update the events until after VOP_POLL. So we could miss * pollwakeup there too. So we always set the bit here just to be * safe. The real performance gain is in subsequent pcache_poll. */ mutex_enter(&pcp->pc_lock); BT_SET(pcp->pc_bitmap, fd); mutex_exit(&pcp->pc_lock); return (0); } /* * The entry is not really deleted. The fields are cleared so that the * entry is no longer useful, but it will remain in the hash table for reuse * later. It will be freed when the polling lwp exits. */ int pcache_delete_fd(pollstate_t *ps, int fd, size_t pos, int which, uint_t cevent) { pollcache_t *pcp = ps->ps_pcache; polldat_t *pdp; xref_t *refp; ASSERT(fd < pcp->pc_mapsize); ASSERT(MUTEX_HELD(&ps->ps_lock)); pdp = pcache_lookup_fd(pcp, fd); ASSERT(pdp != NULL); ASSERT(pdp->pd_count > 0); ASSERT(pdp->pd_ref != NULL); refp = &pdp->pd_ref[which]; if (pdp->pd_count == 1) { pdp->pd_events = 0; refp->xf_position = POLLPOSINVAL; ASSERT(refp->xf_refcnt == 1); refp->xf_refcnt = 0; if (pdp->pd_php) { /* * It is possible for a wakeup thread to get ahead * of the following pollhead_delete and set the bit in * bitmap. It is OK because the bit will be cleared * here anyway. */ pollhead_delete(pdp->pd_php, pdp); pdp->pd_php = NULL; } pdp->pd_count = 0; if (pdp->pd_fp != NULL) { pdp->pd_fp = NULL; delfpollinfo(fd); } mutex_enter(&pcp->pc_lock); BT_CLEAR(pcp->pc_bitmap, fd); mutex_exit(&pcp->pc_lock); return (0); } if ((cevent & POLLCLOSED) == POLLCLOSED) { /* * fd cached here has been closed. This is the first * pcache_delete_fd called after the close. Clean up the * entire entry. */ pcacheset_invalidate(ps, pdp); ASSERT(pdp->pd_php == NULL); mutex_enter(&pcp->pc_lock); BT_CLEAR(pcp->pc_bitmap, fd); mutex_exit(&pcp->pc_lock); return (0); } #ifdef DEBUG if (getf(fd) != NULL) { ASSERT(infpollinfo(fd)); releasef(fd); } #endif /* DEBUG */ pdp->pd_count--; ASSERT(refp->xf_refcnt > 0); if (--refp->xf_refcnt == 0) { refp->xf_position = POLLPOSINVAL; } else { ASSERT(pos >= refp->xf_position); if (pos == refp->xf_position) { /* * The xref position is no longer valid. * Reset it to a special value and let * caller know it needs to updatexref() * with a new xf_position value. */ refp->xf_position = POLLPOSTRANS; return (1); } } return (0); } void pcache_update_xref(pollcache_t *pcp, int fd, ssize_t pos, int which) { polldat_t *pdp; pdp = pcache_lookup_fd(pcp, fd); ASSERT(pdp != NULL); ASSERT(pdp->pd_ref != NULL); pdp->pd_ref[which].xf_position = pos; } #ifdef DEBUG /* * For each polled fd, it's either in the bitmap or cached in * pcache hash table. If this routine returns 0, something is wrong. */ static int pollchecksanity(pollstate_t *ps, nfds_t nfds) { int i; int fd; pollcache_t *pcp = ps->ps_pcache; polldat_t *pdp; pollfd_t *pollfdp = ps->ps_pollfd; file_t *fp; ASSERT(MUTEX_HELD(&ps->ps_lock)); for (i = 0; i < nfds; i++) { fd = pollfdp[i].fd; if (fd < 0) { ASSERT(pollfdp[i].revents == 0); continue; } if (pollfdp[i].revents == POLLNVAL) continue; if ((fp = getf(fd)) == NULL) continue; pdp = pcache_lookup_fd(pcp, fd); ASSERT(pdp != NULL); ASSERT(infpollinfo(fd)); ASSERT(pdp->pd_fp == fp); releasef(fd); if (BT_TEST(pcp->pc_bitmap, fd)) continue; if (pdp->pd_php == NULL) return (0); } return (1); } #endif /* DEBUG */ /* * resolve the difference between the current poll list and a cached one. */ int pcacheset_resolve(pollstate_t *ps, nfds_t nfds, int *fdcntp, int which) { int i; pollcache_t *pcp = ps->ps_pcache; pollfd_t *newlist = NULL; pollfd_t *current = ps->ps_pollfd; pollfd_t *cached; pollcacheset_t *pcsp; int common; int count = 0; int offset; int remain; int fd; file_t *fp; int fdcnt = 0; int cnt = 0; nfds_t old_nfds; int error = 0; int mismatch = 0; ASSERT(MUTEX_HELD(&ps->ps_lock)); #ifdef DEBUG checkpolldat(ps); #endif pcsp = &ps->ps_pcacheset[which]; old_nfds = pcsp->pcs_nfds; common = (nfds > old_nfds) ? old_nfds : nfds; if (nfds != old_nfds) { /* * the length of poll list has changed. allocate a new * pollfd list. */ newlist = kmem_alloc(nfds * sizeof (pollfd_t), KM_SLEEP); bcopy(current, newlist, sizeof (pollfd_t) * nfds); } /* * Compare the overlapping part of the current fd list with the * cached one. Whenever a difference is found, resolve it. * The comparison is done on the current poll list and the * cached list. But we may be setting up the newlist to be the * cached list for next poll. */ cached = pcsp->pcs_pollfd; remain = common; while (count < common) { int tmpfd; pollfd_t *np; np = (newlist != NULL) ? &newlist[count] : NULL; offset = pcacheset_cmp(¤t[count], &cached[count], np, remain); /* * Collect stats. If lists are completed the first time, * it's a hit. Otherwise, it's a partial hit or miss. */ if ((count == 0) && (offset == common)) { pollstats.pollcachehit.value.ui64++; } else { mismatch++; } count += offset; if (offset < remain) { ASSERT(count < common); ASSERT((current[count].fd != cached[count].fd) || (current[count].events != cached[count].events)); /* * Filter out invalid events. */ if (current[count].events & ~VALID_POLL_EVENTS) { if (newlist != NULL) { newlist[count].events = current[count].events &= VALID_POLL_EVENTS; } else { current[count].events &= VALID_POLL_EVENTS; } } /* * when resolving a difference, we always remove the * fd from cache before inserting one into cache. */ if (cached[count].fd >= 0) { tmpfd = cached[count].fd; if (pcache_delete_fd(ps, tmpfd, count, which, (uint_t)cached[count].events)) { /* * This should be rare but needed for * correctness. * * The first appearance in cached list * is being "turned off". The same fd * appear more than once in the cached * poll list. Find the next one on the * list and update the cached * xf_position field. */ for (i = count + 1; i < old_nfds; i++) { if (cached[i].fd == tmpfd) { pcache_update_xref(pcp, tmpfd, (ssize_t)i, which); break; } } ASSERT(i <= old_nfds); } /* * In case a new cache list is allocated, * need to keep both cache lists in sync * b/c the new one can be freed if we have * an error later. */ cached[count].fd = -1; if (newlist != NULL) { newlist[count].fd = -1; } } if ((tmpfd = current[count].fd) >= 0) { /* * add to the cached fd tbl and bitmap. */ if ((fp = getf(tmpfd)) == NULL) { current[count].revents = POLLNVAL; if (newlist != NULL) { newlist[count].fd = -1; } cached[count].fd = -1; fdcnt++; } else { /* * Here we don't care about the * fdcnt. We will examine the bitmap * later and pick up the correct * fdcnt there. So we never bother * to check value of 'cnt'. */ error = pcache_insert(ps, fp, ¤t[count], &cnt, (ssize_t)count, which); /* * if no error, we want to do releasef * after we updated cache poll list * entry so that close() won't race * us. */ if (error) { /* * If we encountered an error, * we have invalidated an * entry in cached poll list * (in pcache_delete_fd() above) * but failed to add one here. * This is OK b/c what's in the * cached list is consistent * with content of cache. * It will not have any ill * effect on next poll(). */ releasef(tmpfd); if (newlist != NULL) { kmem_free(newlist, nfds * sizeof (pollfd_t)); } return (error); } /* * If we have allocated a new(temp) * cache list, we need to keep both * in sync b/c the new one can be freed * if we have an error later. */ if (newlist != NULL) { newlist[count].fd = current[count].fd; newlist[count].events = current[count].events; } cached[count].fd = current[count].fd; cached[count].events = current[count].events; releasef(tmpfd); } } else { current[count].revents = 0; } count++; remain = common - count; } } if (mismatch != 0) { if (mismatch == common) { pollstats.pollcachemiss.value.ui64++; } else { pollstats.pollcachephit.value.ui64++; } } /* * take care of the non overlapping part of a list */ if (nfds > old_nfds) { ASSERT(newlist != NULL); for (i = old_nfds; i < nfds; i++) { /* filter out invalid events */ if (current[i].events & ~VALID_POLL_EVENTS) { newlist[i].events = current[i].events = current[i].events & VALID_POLL_EVENTS; } if ((fd = current[i].fd) < 0) { current[i].revents = 0; continue; } /* * add to the cached fd tbl and bitmap. */ if ((fp = getf(fd)) == NULL) { current[i].revents = POLLNVAL; newlist[i].fd = -1; fdcnt++; continue; } /* * Here we don't care about the * fdcnt. We will examine the bitmap * later and pick up the correct * fdcnt there. So we never bother to * check 'cnt'. */ error = pcache_insert(ps, fp, ¤t[i], &cnt, (ssize_t)i, which); releasef(fd); if (error) { /* * Here we are half way through adding newly * polled fd. Undo enough to keep the cache * list consistent with the cache content. */ pcacheset_remove_list(ps, current, old_nfds, i, which, 0); kmem_free(newlist, nfds * sizeof (pollfd_t)); return (error); } } } if (old_nfds > nfds) { /* * remove the fd's which are no longer polled. */ pcacheset_remove_list(ps, pcsp->pcs_pollfd, nfds, old_nfds, which, 1); } /* * set difference resolved. update nfds and cachedlist * in pollstate struct. */ if (newlist != NULL) { kmem_free(pcsp->pcs_pollfd, old_nfds * sizeof (pollfd_t)); /* * By now, the pollfd.revents field should * all be zeroed. */ pcsp->pcs_pollfd = newlist; pcsp->pcs_nfds = nfds; } ASSERT(*fdcntp == 0); *fdcntp = fdcnt; /* * By now for every fd in pollfdp, one of the following should be * true. Otherwise we will miss a polled event. * * 1. the bit corresponding to the fd in bitmap is set. So VOP_POLL * will be called on this fd in next poll. * 2. the fd is cached in the pcache (i.e. pd_php is set). So * pollnotify will happen. */ ASSERT(pollchecksanity(ps, nfds)); /* * make sure cross reference between cached poll lists and cached * poll fds are correct. */ ASSERT(pollcheckxref(ps, which)); /* * ensure each polldat in pollcache reference a polled fd in * pollcacheset. */ #ifdef DEBUG checkpolldat(ps); #endif return (0); } #ifdef DEBUG static int pollscanrevents(pollcache_t *pcp, pollfd_t *pollfdp, nfds_t nfds) { int i; int reventcnt = 0; for (i = 0; i < nfds; i++) { if (pollfdp[i].fd < 0) { ASSERT(pollfdp[i].revents == 0); continue; } if (pollfdp[i].revents) { reventcnt++; } if (pollfdp[i].revents && (pollfdp[i].revents != POLLNVAL)) { ASSERT(BT_TEST(pcp->pc_bitmap, pollfdp[i].fd)); } } return (reventcnt); } #endif /* DEBUG */ /* * read the bitmap and poll on fds corresponding to the '1' bits. The ps_lock * is held upon entry. */ int pcache_poll(pollfd_t *pollfdp, pollstate_t *ps, nfds_t nfds, int *fdcntp, int which) { int i; pollcache_t *pcp; int fd; int begin, end, done; pollhead_t *php; int fdcnt; int error = 0; file_t *fp; polldat_t *pdp; xref_t *refp; int entry; pcp = ps->ps_pcache; ASSERT(MUTEX_HELD(&ps->ps_lock)); ASSERT(MUTEX_HELD(&pcp->pc_lock)); retry: done = 0; begin = 0; fdcnt = 0; end = pcp->pc_mapend; while ((fdcnt < nfds) && !done) { php = NULL; /* * only poll fds which may have events */ fd = bt_getlowbit(pcp->pc_bitmap, begin, end); ASSERT(fd <= end); if (fd >= 0) { ASSERT(pollcheckrevents(ps, begin, fd, which)); /* * adjust map pointers for next round */ if (fd == end) { done = 1; } else { begin = fd + 1; } /* * A bitmap caches poll state information of * multiple poll lists. Call VOP_POLL only if * the bit corresponds to an fd in this poll * list. */ pdp = pcache_lookup_fd(pcp, fd); ASSERT(pdp != NULL); ASSERT(pdp->pd_ref != NULL); refp = &pdp->pd_ref[which]; if (refp->xf_refcnt == 0) continue; entry = refp->xf_position; ASSERT((entry >= 0) && (entry < nfds)); ASSERT(pollfdp[entry].fd == fd); /* * we are in this routine implies that we have * successfully polled this fd in the past. * Check to see this fd is closed while we are * blocked in poll. This ensures that we don't * miss a close on the fd in the case this fd is * reused. */ if (pdp->pd_fp == NULL) { ASSERT(pdp->pd_count > 0); pollfdp[entry].revents = POLLNVAL; fdcnt++; if (refp->xf_refcnt > 1) { /* * this fd appeared multiple time * in the poll list. Find all of them. */ for (i = entry + 1; i < nfds; i++) { if (pollfdp[i].fd == fd) { pollfdp[i].revents = POLLNVAL; fdcnt++; } } } pcacheset_invalidate(ps, pdp); continue; } /* * We can be here polling a device that is being * closed (i.e. the file pointer is set to NULL, * but pollcacheclean has not happened yet). */ if ((fp = getf(fd)) == NULL) { pollfdp[entry].revents = POLLNVAL; fdcnt++; if (refp->xf_refcnt > 1) { /* * this fd appeared multiple time * in the poll list. Find all of them. */ for (i = entry + 1; i < nfds; i++) { if (pollfdp[i].fd == fd) { pollfdp[i].revents = POLLNVAL; fdcnt++; } } } continue; } ASSERT(pdp->pd_fp == fp); ASSERT(infpollinfo(fd)); /* * Since we no longer hold poll head lock across * VOP_POLL, pollunlock logic can be simplifed. */ ASSERT(pdp->pd_php == NULL || MUTEX_NOT_HELD(PHLOCK(pdp->pd_php))); /* * underlying file systems may set a "pollpending" * flag when it sees the poll may block. Pollwakeup() * is called by wakeup thread if pollpending is set. * Pass a 0 fdcnt so that the underlying file system * will set the "pollpending" flag set when there is * no polled events. * * Use pollfdp[].events for actual polling because * the pd_events is union of all cached poll events * on this fd. The events parameter also affects * how the polled device sets the "poll pending" * flag. */ ASSERT(curthread->t_pollcache == NULL); error = VOP_POLL(fp->f_vnode, pollfdp[entry].events, 0, &pollfdp[entry].revents, &php); /* * releasef after completely done with this cached * poll entry. To prevent close() coming in to clear * this entry. */ if (error) { releasef(fd); break; } /* * layered devices (e.g. console driver) * may change the vnode and thus the pollhead * pointer out from underneath us. */ if (php != NULL && pdp->pd_php != NULL && php != pdp->pd_php) { releasef(fd); pollhead_delete(pdp->pd_php, pdp); pdp->pd_php = php; pollhead_insert(php, pdp); /* * We could have missed a wakeup on the new * target device. Make sure the new target * gets polled once. */ BT_SET(pcp->pc_bitmap, fd); goto retry; } if (pollfdp[entry].revents) { ASSERT(refp->xf_refcnt >= 1); fdcnt++; if (refp->xf_refcnt > 1) { /* * this fd appeared multiple time * in the poll list. This is rare but * we have to look at all of them for * correctness. */ error = plist_chkdupfd(fp, pdp, ps, pollfdp, entry, &fdcnt); if (error > 0) { releasef(fd); break; } if (error < 0) { goto retry; } } releasef(fd); } else { /* * VOP_POLL didn't return any revents. We can * clear the bit in bitmap only if we have the * pollhead ptr cached and no other cached * entry is polling different events on this fd. * VOP_POLL may have dropped the ps_lock. Make * sure pollwakeup has not happened before clear * the bit. */ if ((pdp->pd_php != NULL) && (pollfdp[entry].events == pdp->pd_events) && ((pcp->pc_flag & T_POLLWAKE) == 0)) { BT_CLEAR(pcp->pc_bitmap, fd); } /* * if the fd can be cached now but not before, * do it now. */ if ((pdp->pd_php == NULL) && (php != NULL)) { pdp->pd_php = php; pollhead_insert(php, pdp); /* * We are inserting a polldat struct for * the first time. We may have missed a * wakeup on this device. Re-poll once. * This should be a rare event. */ releasef(fd); goto retry; } if (refp->xf_refcnt > 1) { /* * this fd appeared multiple time * in the poll list. This is rare but * we have to look at all of them for * correctness. */ error = plist_chkdupfd(fp, pdp, ps, pollfdp, entry, &fdcnt); if (error > 0) { releasef(fd); break; } if (error < 0) { goto retry; } } releasef(fd); } } else { done = 1; ASSERT(pollcheckrevents(ps, begin, end + 1, which)); } } if (!error) { ASSERT(*fdcntp + fdcnt == pollscanrevents(pcp, pollfdp, nfds)); *fdcntp += fdcnt; } return (error); } /* * Going through the poll list without much locking. Poll all fds and * cache all valid fds in the pollcache. */ int pcacheset_cache_list(pollstate_t *ps, pollfd_t *fds, int *fdcntp, int which) { pollfd_t *pollfdp = ps->ps_pollfd; pollcacheset_t *pcacheset = ps->ps_pcacheset; pollfd_t *newfdlist; int i; int fd; file_t *fp; int error = 0; ASSERT(MUTEX_HELD(&ps->ps_lock)); ASSERT(which < ps->ps_nsets); ASSERT(pcacheset != NULL); ASSERT(pcacheset[which].pcs_pollfd == NULL); newfdlist = kmem_alloc(ps->ps_nfds * sizeof (pollfd_t), KM_SLEEP); /* * cache the new poll list in pollcachset. */ bcopy(pollfdp, newfdlist, sizeof (pollfd_t) * ps->ps_nfds); pcacheset[which].pcs_pollfd = newfdlist; pcacheset[which].pcs_nfds = ps->ps_nfds; pcacheset[which].pcs_usradr = (uintptr_t)fds; /* * We have saved a copy of current poll fd list in one pollcacheset. * The 'revents' field of the new list is not yet set to 0. Loop * through the new list just to do that is expensive. We do that * while polling the list. */ for (i = 0; i < ps->ps_nfds; i++) { fd = pollfdp[i].fd; /* * We also filter out the illegal poll events in the event * field for the cached poll list/set. */ if (pollfdp[i].events & ~VALID_POLL_EVENTS) { newfdlist[i].events = pollfdp[i].events = pollfdp[i].events & VALID_POLL_EVENTS; } if (fd < 0) { pollfdp[i].revents = 0; continue; } if ((fp = getf(fd)) == NULL) { pollfdp[i].revents = POLLNVAL; /* * invalidate this cache entry in the cached poll list */ newfdlist[i].fd = -1; (*fdcntp)++; continue; } /* * cache this fd. */ error = pcache_insert(ps, fp, &pollfdp[i], fdcntp, (ssize_t)i, which); releasef(fd); if (error) { /* * Here we are half way through caching a new * poll list. Undo every thing. */ pcacheset_remove_list(ps, pollfdp, 0, i, which, 0); kmem_free(newfdlist, ps->ps_nfds * sizeof (pollfd_t)); pcacheset[which].pcs_pollfd = NULL; pcacheset[which].pcs_usradr = NULL; break; } } return (error); } /* * called by pollcacheclean() to set the fp NULL. It also sets polled events * in pcacheset entries to a special events 'POLLCLOSED'. Do a pollwakeup to * wake any sleeping poller, then remove the polldat from the driver. * The routine is called with ps_pcachelock held. */ void pcache_clean_entry(pollstate_t *ps, int fd) { pollcache_t *pcp; polldat_t *pdp; int i; ASSERT(ps != NULL); ASSERT(MUTEX_HELD(&ps->ps_lock)); pcp = ps->ps_pcache; ASSERT(pcp); pdp = pcache_lookup_fd(pcp, fd); ASSERT(pdp != NULL); /* * the corresponding fpollinfo in fi_list has been removed by * a close on this fd. Reset the cached fp ptr here. */ pdp->pd_fp = NULL; /* * XXX - This routine also touches data in pcacheset struct. * * set the event in cached poll lists to POLLCLOSED. This invalidate * the cached poll fd entry in that poll list, which will force a * removal of this cached entry in next poll(). The cleanup is done * at the removal time. */ ASSERT(pdp->pd_ref != NULL); for (i = 0; i < ps->ps_nsets; i++) { xref_t *refp; pollcacheset_t *pcsp; refp = &pdp->pd_ref[i]; if (refp->xf_refcnt) { ASSERT(refp->xf_position >= 0); pcsp = &ps->ps_pcacheset[i]; if (refp->xf_refcnt == 1) { pcsp->pcs_pollfd[refp->xf_position].events = (short)POLLCLOSED; } if (refp->xf_refcnt > 1) { int j; /* * mark every matching entry in pcs_pollfd */ for (j = refp->xf_position; j < pcsp->pcs_nfds; j++) { if (pcsp->pcs_pollfd[j].fd == fd) { pcsp->pcs_pollfd[j].events = (short)POLLCLOSED; } } } } } if (pdp->pd_php) { pollwakeup(pdp->pd_php, POLLHUP); pollhead_delete(pdp->pd_php, pdp); pdp->pd_php = NULL; } } /* * This is the first time this thread has ever polled, * so we have to create its pollstate structure. * This will persist for the life of the thread, * until it calls pollcleanup(). */ pollstate_t * pollstate_create(void) { pollstate_t *ps; ps = kmem_zalloc(sizeof (pollstate_t), KM_SLEEP); ps->ps_nsets = POLLFDSETS; ps->ps_pcacheset = pcacheset_create(ps->ps_nsets); return (ps); } void pollstate_destroy(pollstate_t *ps) { if (ps->ps_pollfd != NULL) { kmem_free(ps->ps_pollfd, ps->ps_nfds * sizeof (pollfd_t)); ps->ps_pollfd = NULL; } if (ps->ps_pcache != NULL) { pcache_destroy(ps->ps_pcache); ps->ps_pcache = NULL; } pcacheset_destroy(ps->ps_pcacheset, ps->ps_nsets); ps->ps_pcacheset = NULL; if (ps->ps_dpbuf != NULL) { kmem_free(ps->ps_dpbuf, ps->ps_dpbufsize * sizeof (pollfd_t)); ps->ps_dpbuf = NULL; } mutex_destroy(&ps->ps_lock); kmem_free(ps, sizeof (pollstate_t)); } /* * We are holding the appropriate uf_lock entering this routine. * Bump up the ps_busy count to prevent the thread from exiting. */ void pollblockexit(fpollinfo_t *fpip) { for (; fpip; fpip = fpip->fp_next) { pollcache_t *pcp = fpip->fp_thread->t_pollstate->ps_pcache; mutex_enter(&pcp->pc_no_exit); pcp->pc_busy++; /* prevents exit()'s */ mutex_exit(&pcp->pc_no_exit); } } /* * Complete phase 2 of cached poll fd cleanup. Call pcache_clean_entry to mark * the pcacheset events field POLLCLOSED to force the next poll() to remove * this cache entry. We can't clean the polldat entry clean up here because * lwp block in poll() needs the info to return. Wakeup anyone blocked in * poll and let exiting lwp go. No lock is help upon entry. So it's OK for * pcache_clean_entry to call pollwakeup(). */ void pollcacheclean(fpollinfo_t *fip, int fd) { struct fpollinfo *fpip, *fpip2; fpip = fip; while (fpip) { pollstate_t *ps = fpip->fp_thread->t_pollstate; pollcache_t *pcp = ps->ps_pcache; mutex_enter(&ps->ps_lock); pcache_clean_entry(ps, fd); mutex_exit(&ps->ps_lock); mutex_enter(&pcp->pc_no_exit); pcp->pc_busy--; if (pcp->pc_busy == 0) { /* * Wakeup the thread waiting in * thread_exit(). */ cv_signal(&pcp->pc_busy_cv); } mutex_exit(&pcp->pc_no_exit); fpip2 = fpip; fpip = fpip->fp_next; kmem_free(fpip2, sizeof (fpollinfo_t)); } } /* * one of the cache line's counter is wrapping around. Reset all cache line * counters to zero except one. This is simplistic, but probably works * effectively. */ void pcacheset_reset_count(pollstate_t *ps, int index) { int i; ASSERT(MUTEX_HELD(&ps->ps_lock)); for (i = 0; i < ps->ps_nsets; i++) { if (ps->ps_pcacheset[i].pcs_pollfd != NULL) { ps->ps_pcacheset[i].pcs_count = 0; } } ps->ps_pcacheset[index].pcs_count = 1; } /* * this routine implements poll cache list replacement policy. * It is currently choose the "least used". */ int pcacheset_replace(pollstate_t *ps) { int i; int index = 0; ASSERT(MUTEX_HELD(&ps->ps_lock)); for (i = 1; i < ps->ps_nsets; i++) { if (ps->ps_pcacheset[index].pcs_count > ps->ps_pcacheset[i].pcs_count) { index = i; } } ps->ps_pcacheset[index].pcs_count = 0; return (index); } /* * this routine is called by strclose to remove remaining polldat struct on * the pollhead list of the device being closed. There are two reasons as why * the polldat structures still remain on the pollhead list: * * (1) The layered device(e.g.the console driver). * In this case, the existence of a polldat implies that the thread putting * the polldat on this list has not exited yet. Before the thread exits, it * will have to hold this pollhead lock to remove the polldat. So holding the * pollhead lock here effectively prevents the thread which put the polldat * on this list from exiting. * * (2) /dev/poll. * When a polled fd is cached in /dev/poll, its polldat will remain on the * pollhead list if the process has not done a POLLREMOVE before closing the * polled fd. We just unlink it here. */ void pollhead_clean(pollhead_t *php) { polldat_t *pdp; /* * In case(1), while we must prevent the thread in question from * exiting, we must also obey the proper locking order, i.e. * (ps_lock -> phlock). */ PH_ENTER(php); while (php->ph_list != NULL) { pollstate_t *ps; pollcache_t *pcp; pdp = php->ph_list; ASSERT(pdp->pd_php == php); if (pdp->pd_thread == NULL) { /* * This is case(2). Since the ph_lock is sufficient * to synchronize this lwp with any other /dev/poll * lwp, just unlink the polldat. */ php->ph_list = pdp->pd_next; pdp->pd_php = NULL; pdp->pd_next = NULL; continue; } ps = pdp->pd_thread->t_pollstate; ASSERT(ps != NULL); pcp = pdp->pd_pcache; ASSERT(pcp != NULL); mutex_enter(&pcp->pc_no_exit); pcp->pc_busy++; /* prevents exit()'s */ mutex_exit(&pcp->pc_no_exit); /* * Now get the locks in proper order to avoid deadlock. */ PH_EXIT(php); mutex_enter(&ps->ps_lock); /* * while we dropped the pollhead lock, the element could be * taken off the list already. */ PH_ENTER(php); if (pdp->pd_php == php) { ASSERT(pdp == php->ph_list); php->ph_list = pdp->pd_next; pdp->pd_php = NULL; pdp->pd_next = NULL; } PH_EXIT(php); mutex_exit(&ps->ps_lock); mutex_enter(&pcp->pc_no_exit); pcp->pc_busy--; if (pcp->pc_busy == 0) { /* * Wakeup the thread waiting in * thread_exit(). */ cv_signal(&pcp->pc_busy_cv); } mutex_exit(&pcp->pc_no_exit); PH_ENTER(php); } PH_EXIT(php); } /* * The remove_list is called to cleanup a partially cached 'current' list or * to remove a partial list which is no longer cached. The flag value of 1 * indicates the second case. */ void pcacheset_remove_list(pollstate_t *ps, pollfd_t *pollfdp, int start, int end, int cacheindex, int flag) { int i; ASSERT(MUTEX_HELD(&ps->ps_lock)); for (i = start; i < end; i++) { if ((pollfdp[i].fd >= 0) && (flag || !(pollfdp[i].revents & POLLNVAL))) { if (pcache_delete_fd(ps, pollfdp[i].fd, i, cacheindex, (uint_t)pollfdp[i].events)) { int j; int fd = pollfdp[i].fd; for (j = i + 1; j < end; j++) { if (pollfdp[j].fd == fd) { pcache_update_xref( ps->ps_pcache, fd, (ssize_t)j, cacheindex); break; } } ASSERT(j <= end); } } } } #ifdef DEBUG #include /* * make sure curthread is not on anyone's pollhead list any more. */ static void pollcheckphlist() { int i; file_t *fp; uf_entry_t *ufp; uf_info_t *fip = P_FINFO(curproc); struct stdata *stp; polldat_t *pdp; mutex_enter(&fip->fi_lock); for (i = 0; i < fip->fi_nfiles; i++) { UF_ENTER(ufp, fip, i); if ((fp = ufp->uf_file) != NULL) { if ((stp = fp->f_vnode->v_stream) != NULL) { PH_ENTER(&stp->sd_pollist); pdp = stp->sd_pollist.ph_list; while (pdp) { ASSERT(pdp->pd_thread != curthread); pdp = pdp->pd_next; } PH_EXIT(&stp->sd_pollist); } } UF_EXIT(ufp); } mutex_exit(&fip->fi_lock); } /* * for resolved set poll list, the xref info in the pcache should be * consistent with this poll list. */ static int pollcheckxref(pollstate_t *ps, int cacheindex) { pollfd_t *pollfdp = ps->ps_pcacheset[cacheindex].pcs_pollfd; pollcache_t *pcp = ps->ps_pcache; polldat_t *pdp; int i; xref_t *refp; for (i = 0; i < ps->ps_pcacheset[cacheindex].pcs_nfds; i++) { if (pollfdp[i].fd < 0) { continue; } pdp = pcache_lookup_fd(pcp, pollfdp[i].fd); ASSERT(pdp != NULL); ASSERT(pdp->pd_ref != NULL); refp = &pdp->pd_ref[cacheindex]; if (refp->xf_position >= 0) { ASSERT(refp->xf_refcnt >= 1); ASSERT(pollfdp[refp->xf_position].fd == pdp->pd_fd); if (refp->xf_refcnt > 1) { int j; int count = 0; for (j = refp->xf_position; j < ps->ps_pcacheset[cacheindex].pcs_nfds; j++) { if (pollfdp[j].fd == pdp->pd_fd) { count++; } } ASSERT(count == refp->xf_refcnt); } } } return (1); } /* * For every cached pollfd, its polldat struct should be consistent with * what is in the pcacheset lists. */ static void checkpolldat(pollstate_t *ps) { pollcache_t *pcp = ps->ps_pcache; polldat_t **hashtbl; int i; hashtbl = pcp->pc_hash; for (i = 0; i < pcp->pc_hashsize; i++) { polldat_t *pdp; for (pdp = hashtbl[i]; pdp; pdp = pdp->pd_hashnext) { ASSERT(pdp->pd_ref != NULL); if (pdp->pd_count > 0) { xref_t *refp; int j; pollcacheset_t *pcsp; pollfd_t *pollfd; for (j = 0; j < ps->ps_nsets; j++) { refp = &pdp->pd_ref[j]; if (refp->xf_refcnt > 0) { pcsp = &ps->ps_pcacheset[j]; ASSERT(refp->xf_position < pcsp->pcs_nfds); pollfd = pcsp->pcs_pollfd; ASSERT(pdp->pd_fd == pollfd[refp->xf_position].fd); } } } } } } /* * every wfd element on ph_list must have a corresponding fpollinfo on the * uf_fpollinfo list. This is a variation of infpollinfo() w/o holding locks. */ void checkwfdlist(vnode_t *vp, fpollinfo_t *fpip) { stdata_t *stp; polldat_t *pdp; fpollinfo_t *fpip2; if ((stp = vp->v_stream) == NULL) { return; } PH_ENTER(&stp->sd_pollist); for (pdp = stp->sd_pollist.ph_list; pdp; pdp = pdp->pd_next) { if (pdp->pd_thread->t_procp == curthread->t_procp) { for (fpip2 = fpip; fpip2; fpip2 = fpip2->fp_next) { if (pdp->pd_thread == fpip2->fp_thread) { break; } } ASSERT(fpip2 != NULL); } } PH_EXIT(&stp->sd_pollist); } /* * For each cached fd whose bit is not set in bitmap, its revents field in * current poll list should be 0. */ static int pollcheckrevents(pollstate_t *ps, int begin, int end, int cacheindex) { pollcache_t *pcp = ps->ps_pcache; pollfd_t *pollfdp = ps->ps_pollfd; int i; for (i = begin; i < end; i++) { polldat_t *pdp; ASSERT(!BT_TEST(pcp->pc_bitmap, i)); pdp = pcache_lookup_fd(pcp, i); if (pdp && pdp->pd_fp != NULL) { xref_t *refp; int entry; ASSERT(pdp->pd_ref != NULL); refp = &pdp->pd_ref[cacheindex]; if (refp->xf_refcnt == 0) { continue; } entry = refp->xf_position; ASSERT(entry >= 0); ASSERT(pollfdp[entry].revents == 0); if (refp->xf_refcnt > 1) { int j; for (j = entry + 1; j < ps->ps_nfds; j++) { if (pollfdp[j].fd == i) { ASSERT(pollfdp[j].revents == 0); } } } } } return (1); } #endif /* DEBUG */ pollcache_t * pcache_alloc() { return (kmem_zalloc(sizeof (pollcache_t), KM_SLEEP)); } void pcache_create(pollcache_t *pcp, nfds_t nfds) { size_t mapsize; /* * allocate enough bits for the poll fd list */ if ((mapsize = POLLMAPCHUNK) <= nfds) { mapsize = (nfds + POLLMAPCHUNK - 1) & ~(POLLMAPCHUNK - 1); } pcp->pc_bitmap = kmem_zalloc((mapsize / BT_NBIPUL) * sizeof (ulong_t), KM_SLEEP); pcp->pc_mapsize = mapsize; /* * The hash size is at least POLLHASHCHUNKSZ. If user polls a large * number of fd to start with, allocate a bigger hash table (to the * nearest multiple of POLLHASHCHUNKSZ) because dynamically growing a * hash table is expensive. */ if (nfds < POLLHASHCHUNKSZ) { pcp->pc_hashsize = POLLHASHCHUNKSZ; } else { pcp->pc_hashsize = (nfds + POLLHASHCHUNKSZ - 1) & ~(POLLHASHCHUNKSZ - 1); } pcp->pc_hash = kmem_zalloc(pcp->pc_hashsize * sizeof (polldat_t *), KM_SLEEP); } void pcache_destroy(pollcache_t *pcp) { polldat_t **hashtbl; int i; hashtbl = pcp->pc_hash; for (i = 0; i < pcp->pc_hashsize; i++) { if (hashtbl[i] != NULL) { polldat_t *pdp, *pdp2; pdp = hashtbl[i]; while (pdp != NULL) { pdp2 = pdp->pd_hashnext; if (pdp->pd_ref != NULL) { kmem_free(pdp->pd_ref, sizeof (xref_t) * pdp->pd_nsets); } kmem_free(pdp, sizeof (polldat_t)); pdp = pdp2; pcp->pc_fdcount--; } } } ASSERT(pcp->pc_fdcount == 0); kmem_free(pcp->pc_hash, sizeof (polldat_t *) * pcp->pc_hashsize); kmem_free(pcp->pc_bitmap, sizeof (ulong_t) * (pcp->pc_mapsize/BT_NBIPUL)); mutex_destroy(&pcp->pc_no_exit); mutex_destroy(&pcp->pc_lock); cv_destroy(&pcp->pc_cv); cv_destroy(&pcp->pc_busy_cv); kmem_free(pcp, sizeof (pollcache_t)); } pollcacheset_t * pcacheset_create(int nsets) { return (kmem_zalloc(sizeof (pollcacheset_t) * nsets, KM_SLEEP)); } void pcacheset_destroy(pollcacheset_t *pcsp, int nsets) { int i; for (i = 0; i < nsets; i++) { if (pcsp[i].pcs_pollfd != NULL) { kmem_free(pcsp[i].pcs_pollfd, pcsp[i].pcs_nfds * sizeof (pollfd_t)); } } kmem_free(pcsp, sizeof (pollcacheset_t) * nsets); } /* * Check each duplicated poll fd in the poll list. It may be necessary to * VOP_POLL the same fd again using different poll events. getf() has been * done by caller. This routine returns 0 if it can sucessfully process the * entire poll fd list. It returns -1 if underlying vnode has changed during * a VOP_POLL, in which case the caller has to repoll. It returns a positive * value if VOP_POLL failed. */ static int plist_chkdupfd(file_t *fp, polldat_t *pdp, pollstate_t *psp, pollfd_t *pollfdp, int entry, int *fdcntp) { int i; int fd; nfds_t nfds = psp->ps_nfds; fd = pollfdp[entry].fd; for (i = entry + 1; i < nfds; i++) { if (pollfdp[i].fd == fd) { if (pollfdp[i].events == pollfdp[entry].events) { if ((pollfdp[i].revents = pollfdp[entry].revents) != 0) { (*fdcntp)++; } } else { int error; pollhead_t *php; pollcache_t *pcp = psp->ps_pcache; /* * the events are different. VOP_POLL on this * fd so that we don't miss any revents. */ php = NULL; ASSERT(curthread->t_pollcache == NULL); error = VOP_POLL(fp->f_vnode, pollfdp[i].events, 0, &pollfdp[i].revents, &php); if (error) { return (error); } /* * layered devices(e.g. console driver) * may change the vnode and thus the pollhead * pointer out from underneath us. */ if (php != NULL && pdp->pd_php != NULL && php != pdp->pd_php) { pollhead_delete(pdp->pd_php, pdp); pdp->pd_php = php; pollhead_insert(php, pdp); /* * We could have missed a wakeup on the * new target device. Make sure the new * target gets polled once. */ BT_SET(pcp->pc_bitmap, fd); return (-1); } if (pollfdp[i].revents) { (*fdcntp)++; } } } } return (0); }