Commit Graph

115 Commits

Author SHA1 Message Date
Edward Tomasz Napierala
4b5c9cf62f Add kern.racct.enable tunable and RACCT_DISABLED config option.
The point of this is to be able to add RACCT (with RACCT_DISABLED)
to GENERIC, to avoid having to rebuild the kernel to use rctl(8).

Differential Revision:	https://reviews.freebsd.org/D2369
Reviewed by:	kib@
MFC after:	1 month
Relnotes:	yes
Sponsored by:	The FreeBSD Foundation
2015-04-29 10:23:02 +00:00
Mateusz Guzik
e015b1ab0a Avoid dynamic syscall overhead for statically compiled modules.
The kernel tracks syscall users so that modules can safely unregister them.

But if the module is not unloadable or was compiled into the kernel, there is
no need to do this.

Achieve this by adding SY_THR_STATIC_KLD macro which expands to SY_THR_STATIC
during kernel build and 0 otherwise.

Reviewed by:	kib (previous version)
MFC after:	2 weeks
2014-10-26 19:42:44 +00:00
Hans Petter Selasky
af3b2549c4 Pull in r267961 and r267973 again. Fix for issues reported will follow. 2014-06-28 03:56:17 +00:00
Glen Barber
37a107a407 Revert r267961, r267973:
These changes prevent sysctl(8) from returning proper output,
such as:

 1) no output from sysctl(8)
 2) erroneously returning ENOMEM with tools like truss(1)
    or uname(1)
 truss: can not get etype: Cannot allocate memory
2014-06-27 22:05:21 +00:00
Hans Petter Selasky
3da1cf1e88 Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after:	2 weeks
Sponsored by:	Mellanox Technologies
2014-06-27 16:33:43 +00:00
Kip Macy
8451d0dd78 In order to maximize the re-usability of kernel code in user space this
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.

Reviewed by:	rwatson
Approved by:	re (bz)
2011-09-16 13:58:51 +00:00
Bjoern A. Zeeb
1080a2c85d Remove semaphore map entry count "semmap" field and its tuning
option that is highly recommended to be adjusted in too much
documentation while doing nothing in FreeBSD since r2729 (rev 1.1).

ipcs(1) needs to be recompiled as it is accessing _KERNEL private
variables.

Reviewed by:	jhb (before comment change on linux code)
Sponsored by:	Sandvine Incorporated
2011-07-14 14:18:14 +00:00
Edward Tomasz Napierala
afcc55f318 All the racct_*() calls need to happen with the proc locked. Fixing this
won't happen before 9.0.  This commit adds "#ifdef RACCT" around all the
"PROC_LOCK(p); racct_whatever(p, ...); PROC_UNLOCK(p)" instances, in order
to avoid useless locking/unlocking in kernels built without "options RACCT".
2011-07-06 20:06:44 +00:00
Edward Tomasz Napierala
b1fb5f9c8d Style fix.
Submitted by:	jhb@
2011-04-06 19:08:50 +00:00
Edward Tomasz Napierala
3bcf74459f Add accounting for SysV-related resources.
Sponsored by:	The FreeBSD Foundation
Reviewed by:	kib (earlier version)
2011-04-06 18:11:24 +00:00
Edward Tomasz Napierala
8caddd81e2 Add ucred pointer to the SysV-related memory structures. This is required
for racct.

Note that after this commit, ipcs(1) needs to be rebuilt.  Otherwise, it will
fail with "ipcs: sysctlbyname: kern.ipc.msqids: Cannot allocate memory".

Sponsored by:	The FreeBSD Foundation
Reviewed by:	kib (earlier version)
2011-04-06 16:59:54 +00:00
Alexander Leidinger
de5b19526b Add some FEATURE macros for various features (AUDIT/CAM/IPC/KTR/MAC/NFS/NTP/
PMC/SYSV/...).

No FreeBSD version bump, the userland application to query the features will
be committed last and can serve as an indication of the availablility if
needed.

Sponsored by:   Google Summer of Code 2010
Submitted by:   kibab
Reviewed by:    arch@ (parts by rwatson, trasz, jhb)
X-MFC after:    to be determined in last commit with code from this project
2011-02-25 10:11:01 +00:00
Matthew D Fleming
2fee06f087 Specify a CTLTYPE_FOO so that a future sysctl(8) change does not need
to rely on the format string.
2011-01-18 21:14:18 +00:00
Rebecca Cran
2baa5cddb6 Add some descriptions to sys/kern sysctls.
PR:	kern/148710
Tested by:	Chip Camden <sterling at camdensoftware.com>
MFC after:	1 week
2010-11-14 06:09:50 +00:00
Ivan Voras
c1e34abff8 In another move to join with the age of the Fruitbat, increase SYSV
shared resources defaults beyond absolute minimums.

The new values are chosen mostly by magic. They are still fairly
small and will need increasing for large installations (especially
SHMMAX). However, they are now enough to e.g. start PostgreSQL
installations with ~~300 users and nearly 512 MB of shared buffers.

Reviewed by:	A short discussion on hackers@
2010-06-11 09:27:33 +00:00
Konstantin Belousov
75d633cbf6 Move SysV IPC freebsd32 compat shims from freebsd32_misc.c to corresponding
sysv_{msg,sem,shm}.c files.

Mark SysV IPC freebsd32 syscalls as NOSTD and add required
SYSCALL_INIT_HELPER/SYSCALL32_INIT_HELPERs to provide auto
register/unregister on module load.

This makes COMPAT_FREEBSD32 functional with SysV IPC compiled and loaded
as modules.

Reviewed by:	jhb
MFC after:	2 weeks
2010-03-19 11:04:42 +00:00
John Baldwin
b648d4806b Change the ABI of some of the structures used by the SYSV IPC API:
- The uid/cuid members of struct ipc_perm are now uid_t instead of unsigned
  short.
- The gid/cgid members of struct ipc_perm are now gid_t instead of unsigned
  short.
- The mode member of struct ipc_perm is now mode_t instead of unsigned short
  (this is merely a style bug).
- The rather dubious padding fields for ABI compat with SV/I386 have been
  removed from struct msqid_ds and struct semid_ds.
- The shm_segsz member of struct shmid_ds is now a size_t instead of an
  int.  This removes the need for the shm_bsegsz member in struct
  shmid_kernel and should allow for complete support of SYSV SHM regions
  >= 2GB.
- The shm_nattch member of struct shmid_ds is now an int instead of a
  short.
- The shm_internal member of struct shmid_ds is now gone.  The internal
  VM object pointer for SHM regions has been moved into struct
  shmid_kernel.
- The existing __semctl(), msgctl(), and shmctl() system call entries are
  now marked COMPAT7 and new versions of those system calls which support
  the new ABI are now present.
- The new system calls are assigned to the FBSD-1.1 version in libc.  The
  FBSD-1.0 symbols in libc now refer to the old COMPAT7 system calls.
- A simplistic framework for tagging system calls with compatibility
  symbol versions has been added to libc.  Version tags are added to
  system calls by adding an appropriate __sym_compat() entry to
  src/lib/libc/incldue/compat.h. [1]

PR:		kern/16195 kern/113218 bin/129855
Reviewed by:	arch@, rwatson
Discussed with:	kan, kib [1]
2009-06-24 21:10:52 +00:00
John Baldwin
45f48220bb Deprecate the msgsys(), semsys(), and shmsys() system calls by moving
them under COMPAT_FREEBSD[4567].  Starting with FreeBSD 5.0 the SYSV IPC
API was implemented via direct system calls (e.g. msgctl(), msgget(), etc.)
rather than indirecting through the var-args *sys() system calls.  The
shmsys() system call was already effectively deprecated for all but
COMPAT_FREEBSD4 already as its implementation for the !COMPAT_FREEBSD4 case
was to simply invoke nosys().
2009-06-24 20:01:13 +00:00
John Baldwin
71361470b1 - Move syscall function argument structure types to be just above the
relevenat system call function.
- Whitespace fixes.
2009-06-24 13:35:38 +00:00
Robert Watson
bcf11e8d00 Move "options MAC" from opt_mac.h to opt_global.h, as it's now in GENERIC
and used in a large number of files, but also because an increasing number
of incorrect uses of MAC calls were sneaking in due to copy-and-paste of
MAC-aware code without the associated opt_mac.h include.

Discussed with:	pjd
2009-06-05 14:55:22 +00:00
Jamie Gritton
0304c73163 Add hierarchical jails. A jail may further virtualize its environment
by creating a child jail, which is visible to that jail and to any
parent jails.  Child jails may be restricted more than their parents,
but never less.  Jail names reflect this hierarchy, being MIB-style
dot-separated strings.

Every thread now points to a jail, the default being prison0, which
contains information about the physical system.  Prison0's root
directory is the same as rootvnode; its hostname is the same as the
global hostname, and its securelevel replaces the global securelevel.
Note that the variable "securelevel" has actually gone away, which
should not cause any problems for code that properly uses
securelevel_gt() and securelevel_ge().

Some jail-related permissions that were kept in global variables and
set via sysctls are now per-jail settings.  The sysctls still exist for
backward compatibility, used only by the now-deprecated jail(2) system
call.

Approved by:	bz (mentor)
2009-05-27 14:11:23 +00:00
Christian Brueffer
1fa80eb15c Fix memory leak in semunload().
PR:		133064
Submitted by:	Mateusz Guzik <mjguzik@gmail.com>
MFC after:	1 week
2009-03-30 15:01:29 +00:00
Konstantin Belousov
137cf3b682 Lock the semaphore identifier lock during semaphore initialization to
guarantee atomicity of the operation for other semaphore consumers.
In particular, this should guard against access to the semaphore with
not done or partially done MAC label assignment.

Reviewed by:	rwatson
MFC after:	1 month
2009-01-15 12:15:46 +00:00
Konstantin Belousov
90a017ba64 It seems that there are at least three issues with IPC_RMID operation
on SysV semaphores.

  The squeeze of the semaphore array in the kern_semctl() modifies
  sem_base for the semaphores with sem_base greater then sem_base of
  the removed semaphore, as well as the values of the semaphores,
  without locking their mutex. This can lead to (killable) hangs or
  unexpected behaviour of the processes performing any sem operations
  while other process does IPC_RMID.

  The semexit_myhook() eventhandler unlocks SEMUNDO_LOCK() while
  accessing *suptr. This allows for IPC_RMID for the sem id to be
  performed in parallel with undo hook referenced by the current undo
  structure. This leads to the panic("semexit - semid not allocated") [1].

  The semaphore creation is protected by Giant, while IPC_RMID is done
  while only semaphore mutex is held. This seems to result in invalid
  values for semtot, causing random ENOSPC error returns [2].

Redo the locking of the semaphores lifetime cycle. Delegate the
sem_mtx to the sole purpose of protecting semget() and
semctl(IPC_RMID). Introduce new sem_undo_mtx to protect SEM_UNDO
handling. Remove the Giant remnants from the code.
Note that  mac_sysvsem_check_semget() and mac_sysvsem_create() are
now called while sem_mtx is held, as well as mac_sysvsem_cleanup() [3].

When semaphore is removed, acquire semaphore locks for all semaphores
with sem_base that is going to be changed by squeeze of the sema
array. The lock order is not important there, because the region is
protected by sem_mtx.

Organize both used and free sem_undo structures into the lists,
protected by sem_undo_mtx. In semexit_myhook(), remove sem_undo
structure that is being processed, from used list, without putting it
onto the free to prevent modifications by other threads. This allows
for sem_undo_lock to be dropped to acquire individial semaphore locks
without violating lock order. Since IPC_RMID may no longer find this
sem_undo, do tolerate references to unallocated semaphores in undo
structure, and check sequential number to not undo unrelated semaphore
with the same id.

While there, convert functions definitions to ANSI C and fix small
style(9) glitches.

Reported by:	Omer Faruk Sen <omerfsen gmail com> [1], pho [2]
Reviewed by:	rwatson [3]
Tested by:	pho
MFC after:	1 month
2009-01-14 15:20:13 +00:00
Oleksandr Tymoshenko
23c8064e66 Renew semaphore's pointer after wakeup since during msleep
sem_base may have been modified by destroying one of semaphores
and semptr would not be valid in this case.

PR: kern/123731
2008-06-19 18:08:42 +00:00
Robert Watson
30d239bc4c Merge first in a series of TrustedBSD MAC Framework KPI changes
from Mac OS X Leopard--rationalize naming for entry points to
the following general forms:

  mac_<object>_<method/action>
  mac_<object>_check_<method/action>

The previous naming scheme was inconsistent and mostly
reversed from the new scheme.  Also, make object types more
consistent and remove spaces from object types that contain
multiple parts ("posix_sem" -> "posixsem") to make mechanical
parsing easier.  Introduce a new "netinet" object type for
certain IPv4/IPv6-related methods.  Also simplify, slightly,
some entry point names.

All MAC policy modules will need to be recompiled, and modules
not updates as part of this commit will need to be modified to
conform to the new KPI.

Sponsored by:	SPARTA (original patches against Mac OS X)
Obtained from:	TrustedBSD Project, Apple Computer
2007-10-24 19:04:04 +00:00
Konstantin Belousov
7aee5992a5 Relock the sema_mtxp unconditionally after copyin() for SETALL case in
kern_semctl. Otherwise, later mtx_unlock() can operate on unlocked mutex.

Submitted by:	rdivacky
MFC after:	3 days
Approved by:	re (kensmith)
2007-07-03 15:58:47 +00:00
Ed Maste
caa8943810 Avoid manipulating semu_list outside of the scope of SEMUNDO_LOCK(). This
would lead to an occasional hang with a cycle in semu_list.

X-Discussed-On: hackers@
2007-03-26 17:41:14 +00:00
Robert Watson
873fbcd776 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.
2007-03-05 13:10:58 +00:00
Robert Watson
0c14ff0eb5 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.
2007-03-04 22:36:48 +00:00
Robert Watson
aed5570872 Complete break-out of sys/sys/mac.h into sys/security/mac/mac_framework.h
begun with a repo-copy of mac.h to mac_framework.h.  sys/mac.h now
contains the userspace and user<->kernel API and definitions, with all
in-kernel interfaces moved to mac_framework.h, which is now included
across most of the kernel instead.

This change is the first step in a larger cleanup and sweep of MAC
Framework interfaces in the kernel, and will not be MFC'd.

Obtained from:	TrustedBSD Project
Sponsored by:	SPARTA
2006-10-22 11:52:19 +00:00
Robert Watson
f50c4fd817 Remove MAC_DEBUG + MPRINTF debugging from System V IPC. This no longer
appears to be serving a useful purpose, as it was used during initial
development of MAC support for System V IPC.

MFC after:	1 month
Obtained from:	TrustedBSD Project
Suggested by:	Christopher dot Vance at SPARTA dot com
2006-09-20 13:40:00 +00:00
Konstantin Belousov
3097d55a39 Use proper format specifier for pointers in debug printfs (turned off
by default).

Approved by:	pjd (mentor)
MFC after:	2 weeks
2006-07-12 11:41:53 +00:00
John Baldwin
b1ee5b654d Rework kern_semctl a bit to always assume the UIO_SYSSPACE case. This
mostly consists of pushing a few copyin's and copyout's up into
__semctl() as all the other callers were already doing the UIO_SYSSPACE
case.  This also changes kern_semctl() to set the return value in a passed
in pointer to a register_t rather than td->td_retval[0] directly so that
callers can only set td->td_retval[0] if all the various copyout's succeed.

As a result of these changes, kern_semctl() no longer does copyin/copyout
(except for GETALL/SETALL) so simplify the locking to acquire the semakptr
mutex before the MAC check and hold it all the way until the end of the
big switch statement.  The GETALL/SETALL cases have to temporarily drop it
while they do copyin/malloc and copyout.  Also, simplify the SETALL case to
remove handling for a non-existent race condition.
2006-07-08 19:51:38 +00:00
John Baldwin
fe95c76276 Fix semctl(2) breakage from the previous commit. Previously __semctl() had
a local 'semid' variable which was the array index and used uap->semid
as the original IPC id.  During the kern_semctl() conversion those two
variables were collapsed into a single 'semid' variable breaking the
places that needed the original IPC ID.  To fix, add a new 'semidx'
variable to hold the array index and leave 'semid' unmolested as the IPC
id.  While I'm here, explicitly document that the (undocumented, at least
in semctl(2)) SEM_STAT command curiously expects an array index in the
'semid' parameter rather than an IPC id.

Submitted by:	maxim
2006-06-29 13:58:36 +00:00
John Baldwin
49d409a108 - Add a kern_semctl() helper function for __semctl(). It accepts a pointer
to a copied-in copy of the 'union semun' and a uioseg to indicate which
  memory space the 'buf' pointer of the union points to.  This is then used
  in linux_semctl() and svr4_sys_semctl() to eliminate use of the stackgap.
- Mark linux_ipc() and svr4_sys_semsys() MPSAFE.
2006-06-27 18:28:50 +00:00
Robert Watson
b37ffd3189 Move some functions and definitions from uipc_socket2.c to uipc_socket.c:
- Move sonewconn(), which creates new sockets for incoming connections on
  listen sockets, so that all socket allocate code is together in
  uipc_socket.c.

- Move 'maxsockets' and associated sysctls to uipc_socket.c with the
  socket allocation code.

- Move kern.ipc sysctl node to uipc_socket.c, add a SYSCTL_DECL() for it
  to sysctl.h and remove lots of scattered implementations in various
  IPC modules.

- Sort sodealloc() after soalloc() in uipc_socket.c for dependency order
  reasons.  Statisticize soalloc() and sodealloc() as they are now
  required only in uipc_socket.c, and are internal to the socket
  implementation.

After this change, socket allocation and deallocation is entirely
centralized in one file, and uipc_socket2.c consists entirely of socket
buffer manipulation and default protocol switch functions.

MFC after:	1 month
2006-06-10 14:34:07 +00:00
Robert Watson
3831e7d7f5 Gratuitous renaming of four System V Semaphore MAC Framework entry
points to convert _sema() to _sem() for consistency purposes with
respect to the other semaphore-related entry points:

mac_init_sysv_sema() -> mac_init_sysv_sem()
mac_destroy_sysv_sem() -> mac_destroy_sysv_sem()
mac_create_sysv_sema() -> mac_create_sysv_sem()
mac_cleanup_sysv_sema() -> mac_cleanup_sysv_sem()

Congruent changes are made to the policy interface to support this.

Obtained from:	TrustedBSD Project
Sponsored by:	SPAWAR, SPARTA
2005-06-07 05:03:28 +00:00
Robert Watson
8e37dd2bb9 Remove end-of-line tabs.
MFC after:	3 days
2005-04-18 11:51:10 +00:00
Sam Leffler
b53d6ac575 check copyin return value
Noticed by:	Coverity Prevent analysis tool
2005-03-19 04:34:23 +00:00
Christian S.J. Peron
84f85aedef Add much needed descriptions for a number of the IPC related sysctl OIDs.
This information will be very useful for people who are tuning applications
which have a dependence on IPC mechanisms.

The following OIDs were documented:

Message queues:
 kern.ipc.msgmax
 kern.ipc.msgmni
 kern.ipc.msgmnb
 kern.ipc.msgtlq
 kern.ipc.msgssz
 kern.ipc.msgseg

Semaphores:
 kern.ipc.semmap
 kern.ipc.semmni
 kern.ipc.semmns
 kern.ipc.semmnu
 kern.ipc.semmsl
 kern.ipc.semopm
 kern.ipc.semume
 kern.ipc.semusz
 kern.ipc.semvmx
 kern.ipc.semaem

Shared memory:
 kern.ipc.shmmax
 kern.ipc.shmmin
 kern.ipc.shmmni
 kern.ipc.shmseg
 kern.ipc.shmall
 kern.ipc.shm_use_phys
 kern.ipc.shm_allow_removed
 kern.ipc.shmsegs

These new descriptions can be viewed using sysctl -d

PR:		kern/65219
Submitted by:	Dan Nelson <dnelson at allantgroup dot com> (modified)
No objections:	developers@
Descriptions reviewed by: gnn
MFC after:	1 week
2005-02-12 01:22:39 +00:00
Robert Watson
a6009aa7c1 Invoke label initialization, creation, cleanup, and tear-down MAC
Framework entry points for System V IPC semaphores.

Submitted by:	Dandekar Hrishikesh <rishi_dandekar at sbcglobal dot net>
Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, SPAWAR, McAfee Research
2005-01-22 19:04:17 +00:00
Warner Losh
9454b2d864 /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
Robert Watson
53d0031d37 Correct two incorrectly merged changes introduced in sysv_sem.c:1.71:
return EINVAL rather than setting error, and don't free sops
unconditionally.  The first change was merged accidentally as part of
the larger set of changes to introduce MAC labels and access control,
and potentially lead to continued processing of a request even after
it was determined to be invalid.  The second change was due to changes
in the semaphore code since the original work was performed.

Pointed out by:	truckman
2004-11-13 08:06:40 +00:00
Robert Watson
921d05b90d Second of several commits to allow kernel System V IPC data structures
to be modified and extended without breaking the user space ABI:

Use _kernel variants on _ds structures for System V sempahores, message
queues, and shared memory.  When interfacing with userspace, export
only the _ds subsets of the _kernel data structures.  A lot of search
and replace.

Define the message structure in the _KERNEL portion of msg.h so that it
can be used by other kernel consumers, but not exposed to user space.

Submitted by:	Dandekar Hrishikesh <rishi_dandekar at sbcglobal dot net>
Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, SPAWAR, McAfee Research
2004-11-12 13:23:47 +00:00
Poul-Henning Kamp
77409fe148 Add missing #include <sys/module.h> 2004-05-30 20:34:58 +00:00
Colin Percival
018e32c194 Adjust the number of processes waiting on a semaphore properly if we're
woken up in the middle of sleeping.

PR:		misc/64347
Reviewed by:	tjr
MFC after:	7 days
2004-03-17 09:37:13 +00:00
Tim J. Robbins
f5925b7436 Reduce the overhead of semop() by using the kernel stack instead of
malloc'd memory to store the operations array if it is small enough
to fit.
2003-12-19 13:07:17 +00:00
Tim J. Robbins
4d93f53e74 Initialize sequence numbers to 0 in seminit() instead of using whatever
garbage happens to be in memory. This did not seem to cause any problems
except making semaphore ID's unpredictable (and ugly in ipcs(1) output).
2003-11-15 11:56:53 +00:00
Tim J. Robbins
541c3b66b5 When there are no free sem_undo structs available in semu_alloc(), only
free one sem_undo with un_cnt == 0 instead of all of them. This is a
temporary workaround until the SLIST_FOREACH_PREVPTR loop gets fixed so
that it doesn't cause cycles in semu_list when removing multiple adjacent
items. It might be easier to just use (doubly-linked) LISTs here instead
of complicated SLIST code to achieve O(1) removals.

This bug manifested itself as a complete lockup under heavy semaphore use
by multiple processes with the SEM_UNDO flag set.

PR:		58984
2003-11-10 07:22:41 +00:00