bdrewery c059a9d249 Track filemon usage via a proc.p_filemon pointer rather than its own lists.
- proc.p_filemon is added which is protected by PROC_LOCK.  This improves
  performance and avoids double-fork issues, taking allproc_lock
  while in syscalls, and walking the process tree in syscalls.  A
  particular proc.p_filemon can only be changed to NULL or another
  filemon, or the filemon inherited, while the filemon->lock is held.
- Filemon are reference counted.  On the last reference the log will be closed.
- When closing the devfs file handle, the filemon will be detached from all
  processes and inheritance prevented.
- Disallow attaching to a process already being traced since filemon is
  typically intended to be used on children only.  This is allowed for
  curproc as bmake relies on this behavior for rare cases when combining
  .MAKE with .META.
- Detach any previously tracked process on ioctl(FILEMON_SET_PID).
- Handle error from devfs_set_cdevpriv() in filemon_open().
- The global filemon lock and lists are removed.
- A free list is no longer kept.  Previously this list was
  forever-expanding and never garbage cleaned.
- No longer loses track of double-forks.  If the process holding the filemon
  handle closes it will close the log rather than wait on a daemonized process,
  but it will log all activity until it closes its handle.  The filemon
  will be removed from the process and not inherited.
- A separate process count is kept only as an optimization for
  forced detachment to avoid taking allproc_lock and walking the entire
  process tree.
- struct filemon access is protected by sx(9) filemon->lock as it was before.
- Add more comments and KASSERTS.

MFC after:	2 weeks
Reviewed by:	kib, mjg, markj (all on previous versions)
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D5520
2016-03-21 20:29:27 +00:00
2016-03-21 18:02:26 +00:00
2016-03-14 16:27:43 +00:00
2016-03-18 02:59:10 +00:00

This is the top level of the FreeBSD source directory.  This file
was last revised on:
$FreeBSD$

For copyright information, please see the file COPYRIGHT in this
directory (additional copyright information also exists for some
sources in this tree - please see the specific source directories for
more information).

The Makefile in this directory supports a number of targets for
building components (or all) of the FreeBSD source tree.  See build(7)
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html
for more information, including setting make(1) variables.

The `buildkernel` and `installkernel` targets build and install
the kernel and the modules (see below).  Please see the top of
the Makefile in this directory for more information on the
standard build targets and compile-time flags.

Building a kernel is a somewhat more involved process.  See build(7), config(8),
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html
for more information.

Note: If you want to build and install the kernel with the
`buildkernel` and `installkernel` targets, you might need to build
world before.  More information is available in the handbook.

The kernel configuration files reside in the sys/<arch>/conf
sub-directory.  GENERIC is the default configuration used in release builds.
NOTES contains entries and documentation for all possible
devices, not just those commonly used.


Source Roadmap:
---------------

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cddl		Various commands and libraries under the Common Development
		and Distribution License.

contrib		Packages contributed by 3rd parties.

crypto		Cryptography stuff (see crypto/README).

etc		Template files for /etc.

games		Amusements.

gnu		Various commands and libraries under the GNU Public License.
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include		System include files.

kerberos5	Kerberos5 (Heimdal) package.

lib		System libraries.

libexec		System daemons.

release		Release building Makefile & associated tools.

rescue		Build system for statically linked /rescue utilities.

sbin		System commands.

secure		Cryptographic libraries and commands.

share		Shared resources.

sys		Kernel sources.

tests		Regression tests which can be run by Kyua.  See tests/README
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tools		Utilities for regression testing and miscellaneous tasks.

usr.bin		User commands.

usr.sbin	System administration commands.


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  http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html
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