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39 .Nm lockmgr_printinfo ,
40 .Nm lockmgr_recursed ,
45 .Nd "lockmgr family of functions"
51 .Fn lockinit "struct lock *lkp" "int prio" "const char *wmesg" "int timo" "int flags"
53 .Fn lockdestroy "struct lock *lkp"
55 .Fn lockmgr "struct lock *lkp" "u_int flags" "struct mtx *ilk"
57 .Fn lockmgr_args "struct lock *lkp" "u_int flags" "struct mtx *ilk" "const char *wmesg" "int prio" "int timo"
59 .Fn lockmgr_args_rw "struct lock *lkp" "u_int flags" "struct rwlock *ilk" "const char *wmesg" "int prio" "int timo"
61 .Fn lockmgr_disown "struct lock *lkp"
63 .Fn lockmgr_printinfo "struct lock *lkp"
65 .Fn lockmgr_recursed "struct lock *lkp"
67 .Fn lockmgr_rw "struct lock *lkp" "u_int flags" "struct rwlock *ilk"
69 .Fn lockmgr_waiters "struct lock *lkp"
71 .Fn lockstatus "struct lock *lkp"
73 .Cd "options INVARIANTS"
74 .Cd "options INVARIANT_SUPPORT"
76 .Fn lockmgr_assert "struct lock *lkp" "int what"
80 function is used to initialize a lock.
81 It must be called before any operation can be performed on a lock.
83 .Bl -tag -width ".Fa wmesg"
85 A pointer to the lock to initialize.
87 The priority passed to
91 This is used for both debugging output and
94 The timeout value passed to
97 The flags the lock is to be initialized with:
98 .Bl -tag -width ".Dv LK_CANRECURSE"
100 Enable adaptive spinning for this lock if the kernel is compiled with the
101 ADAPTIVE_LOCKMGRS option.
103 Allow recursive exclusive locks.
105 Disable lock profiling for this lock.
107 Allow exclusive locks only.
114 should log messages about duplicate locks being acquired.
118 logging for this lock.
122 during a sleep; otherwise, 0 is used.
128 function is used to destroy a lock, and while it is called in a number of
129 places in the kernel, it currently does nothing.
135 functions handle general locking functionality within the kernel, including
136 support for shared and exclusive locks, and recursion.
140 are also able to upgrade and downgrade locks.
143 .Bl -tag -width ".Fa flags"
145 A pointer to the lock to manipulate.
147 Flags indicating what action is to be taken.
148 .Bl -tag -width ".Dv LK_CANRECURSE"
150 Acquire a shared lock.
151 If an exclusive lock is currently held, it will be downgraded.
153 Acquire an exclusive lock.
154 If an exclusive lock is already held, and
156 is not set, the system will
159 Downgrade exclusive lock to a shared lock.
160 Downgrading a shared lock is not permitted.
161 If an exclusive lock has been recursed, all references will be downgraded.
163 Upgrade a shared lock to an exclusive lock.
164 If this call fails, the shared lock is lost.
165 During the upgrade, the shared lock could
166 be temporarily dropped.
167 Attempts to upgrade an exclusive lock will cause a
171 Releasing a lock that is not held can cause a
174 Wait for all activity on the lock to end, then mark it decommissioned.
175 This is used before freeing a lock that is part of a piece of memory that is
178 .In sys/lockmgr.h . )
180 Fail if operation has slept.
182 Do not allow the call to sleep.
183 This can be used to test the lock.
187 checks for this instance.
189 Allow recursion on an exclusive lock.
190 For every lock there must be a release.
192 Unlock the interlock (which should be locked already).
195 An interlock mutex for controlling group access to the lock.
204 is currently owned and not recursed, and will return it unlocked.
222 on a per-instance basis.
223 The specified values will override the default
224 ones, but this can still be used passing, respectively,
225 .Dv LK_WMESG_DEFAULT ,
228 .Dv LK_TIMO_DEFAULT .
232 function switches the owner from the current thread to be
234 if the lock is already held.
237 .Fn lockmgr_printinfo
238 function prints debugging information about the lock.
239 It is used primarily by
245 function returns true if the lock is recursed, 0
250 function returns true if the lock has waiters, 0 otherwise.
254 function returns the status of the lock in relation to the current thread.
257 .Cd "options INVARIANTS"
259 .Cd "options INVARIANT_SUPPORT" ,
264 for the assertions specified in
266 and panics if they are not met.
267 One of the following assertions must be specified:
268 .Bl -tag -width ".Dv KA_UNLOCKED"
270 Assert that the current thread has either a shared or an exclusive lock on the
272 lock pointed to by the first argument.
274 Assert that the current thread has a shared lock on the
276 lock pointed to by the first argument.
278 Assert that the current thread has an exclusive lock on the
280 lock pointed to by the first argument.
282 Assert that the current thread has no lock on the
284 lock pointed to by the first argument.
287 In addition, one of the following optional assertions can be used with
294 .Bl -tag -width ".Dv KA_NOTRECURSED"
296 Assert that the current thread has a recursed lock on
298 .It Dv KA_NOTRECURSED
299 Assert that the current thread does not have a recursed lock on
308 functions return 0 on success and non-zero on failure.
313 .Bl -tag -width ".Dv LK_EXCLUSIVE"
315 An exclusive lock is held by the current thread.
317 An exclusive lock is held by someone other than the current thread.
319 A shared lock is held.
321 The lock is not held by anyone.
331 was requested and another thread had already requested a lock upgrade.
334 was set, and a sleep would have been required.
344 was set in the lock priority, and a signal was delivered during a sleep.
350 was set in the lock priority, a signal was delivered during a sleep,
351 and the system call is to be restarted.
352 .It Bq Er EWOULDBLOCK
353 a non-zero timeout was given, and the timeout expired.
366 must be held prior to calling
370 and will be returned unlocked.
372 Upgrade attempts that fail result in the loss of the lock that
374 Also, it is invalid to upgrade an
375 exclusive lock, and a
377 will be the result of trying.
389 This manual page was written by
390 .An Chad David Aq davidc@acns.ab.ca .