| lock.9 (177697) | lock.9 (177962) |
|---|---|
| 1.\" 2.\" Copyright (C) 2002 Chad David <davidc@acns.ab.ca>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 10 unchanged lines hidden (view full) --- 19.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25.\" DAMAGE. 26.\" | 1.\" 2.\" Copyright (C) 2002 Chad David <davidc@acns.ab.ca>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 10 unchanged lines hidden (view full) --- 19.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25.\" DAMAGE. 26.\" |
| 27.\" $FreeBSD: head/share/man/man9/lock.9 177697 2008-03-28 21:30:37Z brueffer $ | 27.\" $FreeBSD: head/share/man/man9/lock.9 177962 2008-04-06 21:22:12Z attilio $ |
| 28.\" | 28.\" |
| 29.Dd March 28, 2008 | 29.Dd April 6, 2008 |
| 30.Dt LOCK 9 31.Os 32.Sh NAME 33.Nm lockinit , 34.Nm lockdestroy , 35.Nm lockmgr , 36.Nm lockmgr_args , | 30.Dt LOCK 9 31.Os 32.Sh NAME 33.Nm lockinit , 34.Nm lockdestroy , 35.Nm lockmgr , 36.Nm lockmgr_args , |
| 37.Nm lockmgr_args_rw , |
|
| 37.Nm lockmgr_disown , 38.Nm lockmgr_printinfo , 39.Nm lockmgr_recursed , | 38.Nm lockmgr_disown , 39.Nm lockmgr_printinfo , 40.Nm lockmgr_recursed , |
| 41.Nm lockmgr_rw , |
|
| 40.Nm lockmgr_waiters , 41.Nm lockstatus , 42.Nm lockmgr_assert 43.Nd "lockmgr family of functions" 44.Sh SYNOPSIS 45.In sys/types.h 46.In sys/lock.h 47.In sys/lockmgr.h 48.Ft void 49.Fn lockinit "struct lock *lkp" "int prio" "const char *wmesg" "int timo" "int flags" 50.Ft void 51.Fn lockdestroy "struct lock *lkp" 52.Ft int | 42.Nm lockmgr_waiters , 43.Nm lockstatus , 44.Nm lockmgr_assert 45.Nd "lockmgr family of functions" 46.Sh SYNOPSIS 47.In sys/types.h 48.In sys/lock.h 49.In sys/lockmgr.h 50.Ft void 51.Fn lockinit "struct lock *lkp" "int prio" "const char *wmesg" "int timo" "int flags" 52.Ft void 53.Fn lockdestroy "struct lock *lkp" 54.Ft int |
| 53.Fn lockmgr "struct lock *lkp" "u_int flags" "struct mtx *interlkp" | 55.Fn lockmgr "struct lock *lkp" "u_int flags" "struct mtx *ilk" |
| 54.Ft int | 56.Ft int |
| 55.Fn lockmgr_args "struct lock *lkp" "u_int flags" "struct mtx *interlkp" "const char *wmesg" "int prio" "int timo" | 57.Fn lockmgr_args "struct lock *lkp" "u_int flags" "struct mtx *ilk" "const char *wmesg" "int prio" "int timo" 58.Ft int 59.Fn lockmgr_args_rw "struct lock *lkp" "u_int flags" "struct rwlock *ilk" "const char *wmesg" "int prio" "int timo" |
| 56.Ft void 57.Fn lockmgr_disown "struct lock *lkp" 58.Ft void 59.Fn lockmgr_printinfo "struct lock *lkp" 60.Ft int 61.Fn lockmgr_recursed "struct lock *lkp" 62.Ft int | 60.Ft void 61.Fn lockmgr_disown "struct lock *lkp" 62.Ft void 63.Fn lockmgr_printinfo "struct lock *lkp" 64.Ft int 65.Fn lockmgr_recursed "struct lock *lkp" 66.Ft int |
| 67.Fn lockmgr_rw "struct lock *lkp" "u_int flags" "struct rwlock *ilk" 68.Ft int |
|
| 63.Fn lockmgr_waiters "struct lock *lkp" 64.Ft int 65.Fn lockstatus "struct lock *lkp" 66.Pp 67.Cd "options INVARIANTS" 68.Cd "options INVARIANT_SUPPORT" 69.Ft void 70.Fn lockmgr_assert "struct lock *lkp" "int what" --- 45 unchanged lines hidden (view full) --- 116.Pp 117The 118.Fn lockdestroy 119function is used to destroy a lock, and while it is called in a number of 120places in the kernel, it currently does nothing. 121.Pp 122The 123.Fn lockmgr | 69.Fn lockmgr_waiters "struct lock *lkp" 70.Ft int 71.Fn lockstatus "struct lock *lkp" 72.Pp 73.Cd "options INVARIANTS" 74.Cd "options INVARIANT_SUPPORT" 75.Ft void 76.Fn lockmgr_assert "struct lock *lkp" "int what" --- 45 unchanged lines hidden (view full) --- 122.Pp 123The 124.Fn lockdestroy 125function is used to destroy a lock, and while it is called in a number of 126places in the kernel, it currently does nothing. 127.Pp 128The 129.Fn lockmgr |
| 124function handles general locking functionality within the kernel, including | 130and 131.Fn lockmgr_rw 132functions handle general locking functionality within the kernel, including |
| 125support for shared and exclusive locks, and recursion. 126.Fn lockmgr | 133support for shared and exclusive locks, and recursion. 134.Fn lockmgr |
| 127is also able to upgrade and downgrade locks. | 135and 136.Fn lockmgr_rw 137are also able to upgrade and downgrade locks. |
| 128.Pp | 138.Pp |
| 129Its arguments are: 130.Bl -tag -width ".Fa interlkp" | 139Their arguments are: 140.Bl -tag -width ".Fa flags" |
| 131.It Fa lkp 132A pointer to the lock to manipulate. 133.It Fa flags 134Flags indicating what action is to be taken. 135.Bl -tag -width ".Dv LK_CANRECURSE" 136.It Dv LK_SHARED 137Acquire a shared lock. 138If an exclusive lock is currently held, it will be downgraded. --- 30 unchanged lines hidden (view full) --- 169Do not allow the call to sleep. 170This can be used to test the lock. 171.It Dv LK_CANRECURSE 172Allow recursion on an exclusive lock. 173For every lock there must be a release. 174.It Dv LK_INTERLOCK 175Unlock the interlock (which should be locked already). 176.El | 141.It Fa lkp 142A pointer to the lock to manipulate. 143.It Fa flags 144Flags indicating what action is to be taken. 145.Bl -tag -width ".Dv LK_CANRECURSE" 146.It Dv LK_SHARED 147Acquire a shared lock. 148If an exclusive lock is currently held, it will be downgraded. --- 30 unchanged lines hidden (view full) --- 179Do not allow the call to sleep. 180This can be used to test the lock. 181.It Dv LK_CANRECURSE 182Allow recursion on an exclusive lock. 183For every lock there must be a release. 184.It Dv LK_INTERLOCK 185Unlock the interlock (which should be locked already). 186.El |
| 177.It Fa interlkp | 187.It Fa ilk |
| 178An interlock mutex for controlling group access to the lock. 179If 180.Dv LK_INTERLOCK 181is specified, 182.Fn lockmgr | 188An interlock mutex for controlling group access to the lock. 189If 190.Dv LK_INTERLOCK 191is specified, 192.Fn lockmgr |
| 183assumes 184.Fa interlkp | 193and 194.Fn lockmgr_rw 195assume 196.Fa ilk |
| 185is currently owned and not recursed, and will return it unlocked. 186See 187.Xr mtx_assert 9 . 188.El 189.Pp 190The 191.Fn lockmgr_args | 197is currently owned and not recursed, and will return it unlocked. 198See 199.Xr mtx_assert 9 . 200.El 201.Pp 202The 203.Fn lockmgr_args |
| 192function works like | 204and 205.Fn lockmgr_args_rw 206function work like |
| 193.Fn lockmgr | 207.Fn lockmgr |
| 208and 209.Fn lockmgr_rw |
|
| 194but accepting a 195.Fa wmesg , 196.Fa timo 197and 198.Fa prio 199on a per-instance basis. 200The specified values will override the default 201ones, but this can still be used passing, respectively, --- 90 unchanged lines hidden (view full) --- 292usage is highly discouraged. 293They are intended to cater a bad behaviour 294introduced by buffer cache lock handling. 295They will hopefully be 296made useless by revisiting such locks. 297.Sh RETURN VALUES 298The 299.Fn lockmgr | 210but accepting a 211.Fa wmesg , 212.Fa timo 213and 214.Fa prio 215on a per-instance basis. 216The specified values will override the default 217ones, but this can still be used passing, respectively, --- 90 unchanged lines hidden (view full) --- 308usage is highly discouraged. 309They are intended to cater a bad behaviour 310introduced by buffer cache lock handling. 311They will hopefully be 312made useless by revisiting such locks. 313.Sh RETURN VALUES 314The 315.Fn lockmgr |
| 300function returns 0 on success and non-zero on failure. | 316and 317.Fn lockmgr_rw 318functions return 0 on success and non-zero on failure. |
| 301.Pp 302The 303.Fn lockstatus 304function returns: 305.Bl -tag -width ".Dv LK_EXCLUSIVE" 306.It Dv LK_EXCLUSIVE 307An exclusive lock is held by the current thread. 308.It Dv LK_EXCLOTHER 309An exclusive lock is held by someone other than the current thread. 310.It Dv LK_SHARED 311A shared lock is held. 312.It Li 0 313The lock is not held by anyone. 314.El 315.Sh ERRORS 316.Fn lockmgr | 319.Pp 320The 321.Fn lockstatus 322function returns: 323.Bl -tag -width ".Dv LK_EXCLUSIVE" 324.It Dv LK_EXCLUSIVE 325An exclusive lock is held by the current thread. 326.It Dv LK_EXCLOTHER 327An exclusive lock is held by someone other than the current thread. 328.It Dv LK_SHARED 329A shared lock is held. 330.It Li 0 331The lock is not held by anyone. 332.El 333.Sh ERRORS 334.Fn lockmgr |
| 317fails if: | 335and 336.Fn lockmgr_rw 337fail if: |
| 318.Bl -tag -width Er 319.It Bq Er EBUSY 320.Dv LK_FORCEUPGRADE 321was requested and another thread had already requested a lock upgrade. 322.It Bq Er EBUSY 323.Dv LK_NOWAIT 324was set, and a sleep would have been required. 325.It Bq Er ENOLCK 326.Dv LK_SLEEPFAIL 327was set and 328.Fn lockmgr | 338.Bl -tag -width Er 339.It Bq Er EBUSY 340.Dv LK_FORCEUPGRADE 341was requested and another thread had already requested a lock upgrade. 342.It Bq Er EBUSY 343.Dv LK_NOWAIT 344was set, and a sleep would have been required. 345.It Bq Er ENOLCK 346.Dv LK_SLEEPFAIL 347was set and 348.Fn lockmgr |
| 349or 350.Fn lockmgr_rw |
|
| 329did sleep. 330.It Bq Er EINTR 331.Dv PCATCH 332was set in the lock priority, and a signal was delivered during a sleep. 333Note the 334.Er ERESTART 335error below. 336.It Bq Er ERESTART --- 4 unchanged lines hidden (view full) --- 341a non-zero timeout was given, and the timeout expired. 342.El 343.Sh LOCKS 344If 345.Dv LK_INTERLOCK 346is passed in the 347.Fa flags 348argument to | 351did sleep. 352.It Bq Er EINTR 353.Dv PCATCH 354was set in the lock priority, and a signal was delivered during a sleep. 355Note the 356.Er ERESTART 357error below. 358.It Bq Er ERESTART --- 4 unchanged lines hidden (view full) --- 363a non-zero timeout was given, and the timeout expired. 364.El 365.Sh LOCKS 366If 367.Dv LK_INTERLOCK 368is passed in the 369.Fa flags 370argument to |
| 349.Fn lockmgr , | 371.Fn lockmgr 372or 373.Fn lockmgr_rw , |
| 350the | 374the |
| 351.Fa interlkp | 375.Fa ilk |
| 352must be held prior to calling | 376must be held prior to calling |
| 353.Fn lockmgr , | 377.Fn lockmgr 378or 379.Fn lockmgr_rw , |
| 354and will be returned unlocked. 355.Pp 356Upgrade attempts that fail result in the loss of the lock that 357is currently held. 358Also, it is invalid to upgrade an 359exclusive lock, and a 360.Xr panic 9 361will be the result of trying. --- 13 unchanged lines hidden --- | 380and will be returned unlocked. 381.Pp 382Upgrade attempts that fail result in the loss of the lock that 383is currently held. 384Also, it is invalid to upgrade an 385exclusive lock, and a 386.Xr panic 9 387will be the result of trying. --- 13 unchanged lines hidden --- |