1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993, 1995 5 * The Regents of the University of California. 6 * Copyright (c) 2005 Robert N. M. Watson 7 * Copyright (c) 2012 Giovanni Trematerra 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95 35 */ 36 37 #include <sys/param.h> 38 #include <sys/event.h> 39 #include <sys/file.h> 40 #include <sys/filedesc.h> 41 #include <sys/filio.h> 42 #include <sys/fcntl.h> 43 #include <sys/kernel.h> 44 #include <sys/lock.h> 45 #include <sys/mutex.h> 46 #include <sys/malloc.h> 47 #include <sys/selinfo.h> 48 #include <sys/pipe.h> 49 #include <sys/proc.h> 50 #include <sys/signalvar.h> 51 #include <sys/sx.h> 52 #include <sys/systm.h> 53 #include <sys/un.h> 54 #include <sys/unistd.h> 55 #include <sys/vnode.h> 56 57 /* 58 * This structure is associated with the FIFO vnode and stores 59 * the state associated with the FIFO. 60 * Notes about locking: 61 * - fi_pipe is invariant since init time. 62 * - fi_readers and fi_writers are protected by the vnode lock. 63 */ 64 struct fifoinfo { 65 struct pipe *fi_pipe; 66 long fi_readers; 67 long fi_writers; 68 u_int fi_rgen; 69 u_int fi_wgen; 70 }; 71 72 static vop_print_t fifo_print; 73 static vop_open_t fifo_open; 74 static vop_close_t fifo_close; 75 static vop_advlock_t fifo_advlock; 76 77 struct vop_vector fifo_specops = { 78 .vop_default = &default_vnodeops, 79 80 .vop_advlock = fifo_advlock, 81 .vop_close = fifo_close, 82 .vop_create = VOP_PANIC, 83 .vop_getattr = VOP_EBADF, 84 .vop_ioctl = VOP_PANIC, 85 .vop_link = VOP_PANIC, 86 .vop_mkdir = VOP_PANIC, 87 .vop_mknod = VOP_PANIC, 88 .vop_open = fifo_open, 89 .vop_pathconf = VOP_PANIC, 90 .vop_print = fifo_print, 91 .vop_read = VOP_PANIC, 92 .vop_readdir = VOP_PANIC, 93 .vop_readlink = VOP_PANIC, 94 .vop_reallocblks = VOP_PANIC, 95 .vop_reclaim = VOP_NULL, 96 .vop_remove = VOP_PANIC, 97 .vop_rename = VOP_PANIC, 98 .vop_rmdir = VOP_PANIC, 99 .vop_setattr = VOP_EBADF, 100 .vop_symlink = VOP_PANIC, 101 .vop_write = VOP_PANIC, 102 }; 103 VFS_VOP_VECTOR_REGISTER(fifo_specops); 104 105 /* 106 * Dispose of fifo resources. 107 */ 108 static void 109 fifo_cleanup(struct vnode *vp) 110 { 111 struct fifoinfo *fip; 112 113 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup"); 114 fip = vp->v_fifoinfo; 115 if (fip->fi_readers == 0 && fip->fi_writers == 0) { 116 vp->v_fifoinfo = NULL; 117 pipe_dtor(fip->fi_pipe); 118 free(fip, M_VNODE); 119 } 120 } 121 122 /* 123 * Open called to set up a new instance of a fifo or 124 * to find an active instance of a fifo. 125 */ 126 /* ARGSUSED */ 127 static int 128 fifo_open(struct vop_open_args *ap) 129 { 130 struct vnode *vp; 131 struct file *fp; 132 struct thread *td; 133 struct fifoinfo *fip; 134 struct pipe *fpipe; 135 u_int gen; 136 int error, stops_deferred; 137 138 vp = ap->a_vp; 139 fp = ap->a_fp; 140 td = ap->a_td; 141 ASSERT_VOP_ELOCKED(vp, "fifo_open"); 142 if (fp == NULL || (ap->a_mode & FEXEC) != 0) 143 return (EINVAL); 144 if ((fip = vp->v_fifoinfo) == NULL) { 145 error = pipe_named_ctor(&fpipe, td); 146 if (error != 0) 147 return (error); 148 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK | M_ZERO); 149 fip->fi_pipe = fpipe; 150 fpipe->pipe_wgen = 0; 151 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race")); 152 vp->v_fifoinfo = fip; 153 } 154 fpipe = fip->fi_pipe; 155 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL")); 156 157 /* 158 * Use the pipe mutex here, in addition to the vnode lock, 159 * in order to allow vnode lock dropping before msleep() calls 160 * and still avoiding missed wakeups. 161 */ 162 PIPE_LOCK(fpipe); 163 if (ap->a_mode & FREAD) { 164 fip->fi_readers++; 165 fip->fi_rgen++; 166 if (fip->fi_readers == 1) { 167 fpipe->pipe_state &= ~PIPE_EOF; 168 if (fip->fi_writers > 0) { 169 wakeup(&fip->fi_writers); 170 pipeselwakeup(fpipe); 171 } 172 } 173 fp->f_pipegen = fpipe->pipe_wgen - fip->fi_writers; 174 } 175 if (ap->a_mode & FWRITE) { 176 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) { 177 PIPE_UNLOCK(fpipe); 178 if (fip->fi_writers == 0) 179 fifo_cleanup(vp); 180 return (ENXIO); 181 } 182 fip->fi_writers++; 183 fip->fi_wgen++; 184 if (fip->fi_writers == 1) { 185 fpipe->pipe_state &= ~PIPE_EOF; 186 if (fip->fi_readers > 0) { 187 wakeup(&fip->fi_readers); 188 pipeselwakeup(fpipe); 189 } 190 } 191 } 192 if ((ap->a_mode & O_NONBLOCK) == 0) { 193 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) { 194 gen = fip->fi_wgen; 195 VOP_UNLOCK(vp); 196 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF); 197 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe), 198 PDROP | PCATCH | PSOCK, "fifoor", 0); 199 sigallowstop(stops_deferred); 200 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 201 if (error != 0 && gen == fip->fi_wgen) { 202 fip->fi_readers--; 203 if (fip->fi_readers == 0) { 204 PIPE_LOCK(fpipe); 205 fpipe->pipe_state |= PIPE_EOF; 206 if (fpipe->pipe_state & PIPE_WANTW) 207 wakeup(fpipe); 208 pipeselwakeup(fpipe); 209 PIPE_UNLOCK(fpipe); 210 fifo_cleanup(vp); 211 } 212 return (error); 213 } 214 PIPE_LOCK(fpipe); 215 /* 216 * We must have got woken up because we had a writer. 217 * That (and not still having one) is the condition 218 * that we must wait for. 219 */ 220 } 221 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) { 222 gen = fip->fi_rgen; 223 VOP_UNLOCK(vp); 224 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF); 225 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe), 226 PDROP | PCATCH | PSOCK, "fifoow", 0); 227 sigallowstop(stops_deferred); 228 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 229 if (error != 0 && gen == fip->fi_rgen) { 230 fip->fi_writers--; 231 if (fip->fi_writers == 0) { 232 PIPE_LOCK(fpipe); 233 fpipe->pipe_state |= PIPE_EOF; 234 if (fpipe->pipe_state & PIPE_WANTR) 235 wakeup(fpipe); 236 fpipe->pipe_wgen++; 237 pipeselwakeup(fpipe); 238 PIPE_UNLOCK(fpipe); 239 fifo_cleanup(vp); 240 } 241 return (error); 242 } 243 /* 244 * We must have got woken up because we had 245 * a reader. That (and not still having one) 246 * is the condition that we must wait for. 247 */ 248 PIPE_LOCK(fpipe); 249 } 250 } 251 PIPE_UNLOCK(fpipe); 252 KASSERT(fp != NULL, ("can't fifo/vnode bypass")); 253 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open")); 254 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops); 255 return (0); 256 } 257 258 /* 259 * Device close routine 260 */ 261 /* ARGSUSED */ 262 static int 263 fifo_close(struct vop_close_args *ap) 264 { 265 struct vnode *vp; 266 struct fifoinfo *fip; 267 struct pipe *cpipe; 268 269 vp = ap->a_vp; 270 ASSERT_VOP_ELOCKED(vp, "fifo_close"); 271 fip = vp->v_fifoinfo; 272 273 /* 274 * During open, it is possible that the fifo vnode is relocked 275 * after the vnode is instantiated but before VOP_OPEN() is 276 * done. For instance, vn_open_vnode() might need to upgrade 277 * vnode lock, or ffs_vput_pair() needs to unlock vp to sync 278 * dvp. In this case, reclaim can observe us with v_fifoinfo 279 * equal to NULL. 280 */ 281 if (fip == NULL) 282 return (0); 283 284 cpipe = fip->fi_pipe; 285 if (ap->a_fflag & FREAD) { 286 fip->fi_readers--; 287 if (fip->fi_readers == 0) { 288 PIPE_LOCK(cpipe); 289 cpipe->pipe_state |= PIPE_EOF; 290 if ((cpipe->pipe_state & PIPE_WANTW)) { 291 cpipe->pipe_state &= ~PIPE_WANTW; 292 wakeup(cpipe); 293 } 294 pipeselwakeup(cpipe); 295 PIPE_UNLOCK(cpipe); 296 } 297 } 298 if (ap->a_fflag & FWRITE) { 299 fip->fi_writers--; 300 if (fip->fi_writers == 0) { 301 PIPE_LOCK(cpipe); 302 cpipe->pipe_state |= PIPE_EOF; 303 if ((cpipe->pipe_state & PIPE_WANTR)) { 304 cpipe->pipe_state &= ~PIPE_WANTR; 305 wakeup(cpipe); 306 } 307 cpipe->pipe_wgen++; 308 pipeselwakeup(cpipe); 309 PIPE_UNLOCK(cpipe); 310 } 311 } 312 fifo_cleanup(vp); 313 return (0); 314 } 315 316 /* 317 * Print out internal contents of a fifo vnode. 318 */ 319 int 320 fifo_printinfo(struct vnode *vp) 321 { 322 struct fifoinfo *fip = vp->v_fifoinfo; 323 324 if (fip == NULL){ 325 printf(", NULL v_fifoinfo"); 326 return (0); 327 } 328 printf(", fifo with %ld readers and %ld writers", 329 fip->fi_readers, fip->fi_writers); 330 return (0); 331 } 332 333 /* 334 * Print out the contents of a fifo vnode. 335 */ 336 static int 337 fifo_print(struct vop_print_args *ap) 338 { 339 printf(" "); 340 fifo_printinfo(ap->a_vp); 341 printf("\n"); 342 return (0); 343 } 344 345 /* 346 * Fifo advisory byte-level locks. 347 */ 348 /* ARGSUSED */ 349 static int 350 fifo_advlock(struct vop_advlock_args *ap) 351 { 352 353 if ((ap->a_flags & F_FLOCK) == 0) 354 return (EINVAL); 355 return (vop_stdadvlock(ap)); 356 } 357