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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 "const struct lock *lkp"
65 .Fn lockmgr_recursed "const struct lock *lkp"
67 .Fn lockmgr_rw "struct lock *lkp" "u_int flags" "struct rwlock *ilk"
69 .Fn lockmgr_waiters "const struct lock *lkp"
71 .Fn lockstatus "const struct lock *lkp"
73 .Cd "options INVARIANTS"
74 .Cd "options INVARIANT_SUPPORT"
76 .Fn lockmgr_assert "const 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,
155 Acquire an exclusive lock.
156 If an exclusive lock is already held, and
158 is not set, the system will
161 Downgrade exclusive lock to a shared lock.
162 Downgrading a shared lock is not permitted.
163 If an exclusive lock has been recursed, the system will
166 Upgrade a shared lock to an exclusive lock.
167 If this call fails, the shared lock is lost, even if the
170 During the upgrade, the shared lock could
171 be temporarily dropped.
172 Attempts to upgrade an exclusive lock will cause a
175 Try to upgrade a shared lock to an exclusive lock.
176 The failure to upgrade does not result in the dropping
177 of the shared lock ownership.
180 Releasing a lock that is not held can cause a
183 Wait for all activity on the lock to end, then mark it decommissioned.
184 This is used before freeing a lock that is part of a piece of memory that is
187 .In sys/lockmgr.h . )
189 Fail if operation has slept.
191 Do not allow the call to sleep.
192 This can be used to test the lock.
196 checks for this instance.
198 Allow recursion on an exclusive lock.
199 For every lock there must be a release.
201 Unlock the interlock (which should be locked already).
204 An interlock mutex for controlling group access to the lock.
213 is currently owned and not recursed, and will return it unlocked.
231 on a per-instance basis.
232 The specified values will override the default
233 ones, but this can still be used passing, respectively,
234 .Dv LK_WMESG_DEFAULT ,
237 .Dv LK_TIMO_DEFAULT .
241 function switches the owner from the current thread to be
243 if the lock is already held.
246 .Fn lockmgr_printinfo
247 function prints debugging information about the lock.
248 It is used primarily by
254 function returns true if the lock is recursed, 0
259 function returns true if the lock has waiters, 0 otherwise.
263 function returns the status of the lock in relation to the current thread.
266 .Cd "options INVARIANTS"
268 .Cd "options INVARIANT_SUPPORT" ,
273 for the assertions specified in
275 and panics if they are not met.
276 One of the following assertions must be specified:
277 .Bl -tag -width ".Dv KA_UNLOCKED"
279 Assert that the current thread has either a shared or an exclusive lock on the
281 lock pointed to by the first argument.
283 Assert that the current thread has a shared lock on the
285 lock pointed to by the first argument.
287 Assert that the current thread has an exclusive lock on the
289 lock pointed to by the first argument.
291 Assert that the current thread has no lock on the
293 lock pointed to by the first argument.
296 In addition, one of the following optional assertions can be used with
303 .Bl -tag -width ".Dv KA_NOTRECURSED"
305 Assert that the current thread has a recursed lock on
307 .It Dv KA_NOTRECURSED
308 Assert that the current thread does not have a recursed lock on
316 functions return 0 on success and non-zero on failure.
321 .Bl -tag -width ".Dv LK_EXCLUSIVE"
323 An exclusive lock is held by the current thread.
325 An exclusive lock is held by someone other than the current thread.
327 A shared lock is held.
329 The lock is not held by anyone.
339 was requested and another thread had already requested a lock upgrade.
342 was set, and a sleep would have been required, or
344 operation was not able to upgrade the lock.
354 was set in the lock priority, and a signal was delivered during a sleep.
360 was set in the lock priority, a signal was delivered during a sleep,
361 and the system call is to be restarted.
362 .It Bq Er EWOULDBLOCK
363 a non-zero timeout was given, and the timeout expired.
376 must be held prior to calling
380 and will be returned unlocked.
382 Upgrade attempts that fail result in the loss of the lock that
384 Also, it is invalid to upgrade an
385 exclusive lock, and a
387 will be the result of trying.
399 This manual page was written by
400 .An Chad David Aq davidc@acns.ab.ca .