Reverse if() logic to improve readability.

Reviewed by: ru

- Remove stale comment.
- In the last revision the code was changed to use maxfilesperproc rather than
the per-process file limit to restrict the size of the poll array. This
eliminates a sig

- Remove stale comment.
- In the last revision the code was changed to use maxfilesperproc rather than
the per-process file limit to restrict the size of the poll array. This
eliminates a significant source of process lock contention in multithreaded
programs and is cheaper. This had been committed with the wrong batch of
changes.

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- Relax requirements for p_numthreads, p_threads, p_swtick, and p_nice from
requiring the per-process spinlock to only requiring the process lock.
- Reflect these changes in the proc.h documentat

- Relax requirements for p_numthreads, p_threads, p_swtick, and p_nice from
requiring the per-process spinlock to only requiring the process lock.
- Reflect these changes in the proc.h documentation and consumers throughout
the kernel. This is a substantial reduction in locking cost for these
fields and was made possible by recent changes to threading support.

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Make ftruncate a 'struct file' operation rather than a vnode operation.
This makes it possible to support ftruncate() on non-vnode file types in
the future.
- 'struct fileops' grows a 'fo_truncate' m

Make ftruncate a 'struct file' operation rather than a vnode operation.
This makes it possible to support ftruncate() on non-vnode file types in
the future.
- 'struct fileops' grows a 'fo_truncate' method to handle an ftruncate() on
a given file descriptor.
- ftruncate() moves to kern/sys_generic.c and now just fetches a file
object and invokes fo_truncate().
- The vnode-specific portions of ftruncate() move to vn_truncate() in
vfs_vnops.c which implements fo_truncate() for vnode file types.
- Non-vnode file types return EINVAL in their fo_truncate() method.

Submitted by: rwatson

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Remove explicit locking of struct file.
- Introduce a finit() which is used to initailize the fields of struct file
in such a way that the ops vector is only valid after the data, type,
and fl

Remove explicit locking of struct file.
- Introduce a finit() which is used to initailize the fields of struct file
in such a way that the ops vector is only valid after the data, type,
and flags are valid.
- Protect f_flag and f_count with atomic operations.
- Remove the global list of all files and associated accounting.
- Rewrite the unp garbage collection such that it no longer requires
the global list of all files and instead uses a list of all unp sockets.
- Mark sockets in the accept queue so we don't incorrectly gc them.

Tested by: kris, pho

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Refactor select to reduce contention and hide internal implementation
details from consumers.

- Track individual selecters on a per-descriptor basis such that there
are no longer collisions and

Refactor select to reduce contention and hide internal implementation
details from consumers.

- Track individual selecters on a per-descriptor basis such that there
are no longer collisions and after sleeping for events only those
descriptors which triggered events must be rescaned.
- Protect the selinfo (per descriptor) structure with a mtx pool mutex.
mtx pool mutexes were chosen to preserve api compatibility with
existing code which does nothing but bzero() to setup selinfo
structures.
- Use a per-thread wait channel rather than a global wait channel.
- Hide select implementation details in a seltd structure which is
opaque to the rest of the kernel.
- Provide a 'selsocket' interface for those kernel consumers who wish to
select on a socket when they have no fd so they no longer have to
be aware of select implementation details.

Tested by: kris
Reviewed on: arch

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generally we are interested in what thread did something as
opposed to what process. Since threads by default have teh name of the
process unless over-written with more useful information, just print

generally we are interested in what thread did something as
opposed to what process. Since threads by default have teh name of the
process unless over-written with more useful information, just print the
thread name instead.

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Add freebsd6_ wrappers for mmap/lseek/pread/pwrite/truncate/ftruncate

Approved by: re (kensmith)

Commit 14/14 of sched_lock decomposition.
- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-p

Commit 14/14 of sched_lock decomposition.
- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-process
scheduling synchronization.

Tested by: kris, current@
Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)

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Remove unneeded include files.

Replace custom file descriptor array sleep lock constructed using a mutex
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared

Replace custom file descriptor array sleep lock constructed using a mutex
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared locking for
frequent lookup operations, reduced general overhead, and reduced overhead
in the event of contention. All of these are imported for threaded
applications where simultaneous access to a shared file descriptor array
occurs frequently. Kris has reported 2x-4x transaction rate improvements
on 8-core MySQL benchmarks; smaller improvements can be expected for many
workloads as a result of reduced overhead.

- Generally eliminate the distinction between "fast" and regular
acquisisition of the filedesc lock; the plan is that they will now all
be fast. Change all locking instances to either shared or exclusive
locks.

- Correct a bug (pointed out by kib) in fdfree() where previously msleep()
was called without the mutex held; sx_sleep() is now always called with
the sxlock held exclusively.

- Universally hold the struct file lock over changes to struct file,
rather than the filedesc lock or no lock. Always update the f_ops
field last. A further memory barrier is required here in the future
(discussed with jhb).

- Improve locking and reference management in linux_at(), which fails to
properly acquire vnode references before using vnode pointers. Annotate
improper use of vn_fullpath(), which will be replaced at a future date.

In fcntl(), we conservatively acquire an exclusive lock, even though in
some cases a shared lock may be sufficient, which should be revisited.
The dropping of the filedesc lock in fdgrowtable() is no longer required
as the sxlock can be held over the sleep operation; we should consider
removing that (pointed out by attilio).

Tested by: kris
Discussed with: jhb, kris, attilio, jeff

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Further system call comment cleanup:

- Remove also "MP SAFE" after prior "MPSAFE" pass. (suggested by bde)
- Remove extra blank lines in some cases.
- Add extra blank lines in some cases.
- Remove n

Further system call comment cleanup:

- Remove also "MP SAFE" after prior "MPSAFE" pass. (suggested by bde)
- Remove extra blank lines in some cases.
- Add extra blank lines in some cases.
- Remove no-op comments consisting solely of the function name, the word
"syscall", or the system call name.
- Add punctuation.
- Re-wrap some comments.

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Remove 'MPSAFE' annotations from the comments above most system calls: all
system calls now enter without Giant held, and then in some cases, acquire
Giant explicitly.

Remove a number of other MPSAF

Remove 'MPSAFE' annotations from the comments above most system calls: all
system calls now enter without Giant held, and then in some cases, acquire
Giant explicitly.

Remove a number of other MPSAFE annotations in the credential code and
tweak one or two other adjacent comments.

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Do not dispatch SIGPIPE from the generic write path for a socket; with
this patch the code behaves according to the comment on the line above.

Without this patch, a socket could cause SIGPIPE to be

Do not dispatch SIGPIPE from the generic write path for a socket; with
this patch the code behaves according to the comment on the line above.

Without this patch, a socket could cause SIGPIPE to be delivered to its
process, once with SO_NOSIGPIPE set, and twice without.

With this patch, the kernel now passes the sigpipe regression test.

Tested by: Anton Yuzhaninov
MFC after: 1 week

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Prevent IOC_IN with zero size argument (this is only supported
if backward copatibility options are present) from attempting
to free memory that wasn't allocated. This is an old bug, and
previously

Prevent IOC_IN with zero size argument (this is only supported
if backward copatibility options are present) from attempting
to free memory that wasn't allocated. This is an old bug, and
previously it would attempt to free a null pointer. I noticed
this bug when working on the previous revision, but forgot to
fix it.

Security: local DoS
Reported by: Peter Holm
MFC after: 3 days

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Fix our ioctl(2) implementation when the argument is "int". New
ioctls passing integer arguments should use the _IOWINT() macro.
This fixes a lot of ioctl's not working on sparc64, most notable
bein

Fix our ioctl(2) implementation when the argument is "int". New
ioctls passing integer arguments should use the _IOWINT() macro.
This fixes a lot of ioctl's not working on sparc64, most notable
being keyboard/syscons ioctls.

Full ABI compatibility is provided, with the bonus of fixing the
handling of old ioctls on sparc64.

Reviewed by: bde (with contributions)
Tested by: emax, marius
MFC after: 1 week

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- Split ioctl() up into ioctl() and kern_ioctl(). The kern_ioctl() assumes
that the 'data' pointer is already setup to point to a valid KVM buffer
or contains the copied-in data from userland as

- Split ioctl() up into ioctl() and kern_ioctl(). The kern_ioctl() assumes
that the 'data' pointer is already setup to point to a valid KVM buffer
or contains the copied-in data from userland as appropriate (ioctl(2)
still does this). kern_ioctl() takes care of looking up a file pointer,
implementing FIONCLEX and FIOCLEX, and calling fi_ioctl().
- Use kern_ioctl() to implement xenix_rdchk() instead of using the stackgap
and mark xenix_rdchk() MPSAFE.

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Return error from fget_write() rather than hardcoding EBADF now that
fget_write() DTRT.

Requested by: bde

Remove XXX comments complaining that write(2) on a read-only descriptor
returns EBADF. That errno is correct and is mandated by POSIX. It also
goes back to revision 1.1 of our CVS history (i.e. 4.4

Remove XXX comments complaining that write(2) on a read-only descriptor
returns EBADF. That errno is correct and is mandated by POSIX. It also
goes back to revision 1.1 of our CVS history (i.e. 4.4BSD).

The _fget() function should probably also be upated as it currently returns
EINVAL in that case rather than EBADF. (It does return EBADF for reads
on a write-only descriptor without any XXX comments oddly enough.)

Discussed with: scottl, grog, mjacob, bde

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- Add two new system calls: preadv() and pwritev() which are like readv()
and writev() except that they take an additional offset argument and do
not change the current file position. In SAT spe

- Add two new system calls: preadv() and pwritev() which are like readv()
and writev() except that they take an additional offset argument and do
not change the current file position. In SAT speak:
preadv:readv::pread:read and pwritev:writev::pwrite:write.
- Try to reduce code duplication some by merging most of the old
kern_foov() and dofilefoo() functions into new dofilefoo() functions
that are called by kern_foov() and kern_pfoov(). The non-v functions
now all generate a simple uio on the stack from the passed in arguments
and then call kern_foov(). For example, read() now just builds a uio and
calls kern_readv() and pwrite() just builds a uio and calls kern_pwritev().

PR: kern/80362
Submitted by: Marc Olzheim marcolz at stack dot nl (1)
Approved by: re (scottl)
MFC after: 1 week

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Conditionally weaken sys_generic.c rev 1.136 to allow certain dubious
ioctl numbers in backwards compatability mode. eg: an IOC_IN ioctl with
a size of zero. Traditionally this was what you did bef

Conditionally weaken sys_generic.c rev 1.136 to allow certain dubious
ioctl numbers in backwards compatability mode. eg: an IOC_IN ioctl with
a size of zero. Traditionally this was what you did before IOC_VOID
existed, and we had some established users of this in the tree, namely
procfs. Certain 3rd party drivers with binary userland components also
have this too.

This is necessary to have 4.x and 5.x binaries use these ioctl's. We
found this at work when trying to run 4.x binaries.

Approved by: re

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Implement kern_adjtime(), kern_readv(), kern_sched_rr_get_interval(),
kern_settimeofday(), and kern_writev() to allow for further stackgap
reduction in the compat ABIs.

Declare "cnt" (a number of bytes to read or write) as an "ssize_t", not
as a "long" in dofileread() and dofilewrite().

Discussed with: jhb

Previously a read of zero bytes got handled in devfs:vop_read() but I
missed that when the vnode bypass was introduced.

Deal with zero length transfers before we even get to fo_ops->fo_read().

Foun

Previously a read of zero bytes got handled in devfs:vop_read() but I
missed that when the vnode bypass was introduced.

Deal with zero length transfers before we even get to fo_ops->fo_read().

Found by: Slawa Olhovchenkov <slwzxy.spb.ru@zxy.spb.ru>
PR: 75758

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Detect sign-extension bugs in the ioctl(2) command argument: Truncate
to 32 bits and print warning.