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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,
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.
168 During the upgrade, the shared lock could
169 be temporarily dropped.
170 Attempts to upgrade an exclusive lock will cause a
174 Releasing a lock that is not held can cause a
177 Wait for all activity on the lock to end, then mark it decommissioned.
178 This is used before freeing a lock that is part of a piece of memory that is
181 .In sys/lockmgr.h . )
183 Fail if operation has slept.
185 Do not allow the call to sleep.
186 This can be used to test the lock.
190 checks for this instance.
192 Allow recursion on an exclusive lock.
193 For every lock there must be a release.
195 Unlock the interlock (which should be locked already).
198 An interlock mutex for controlling group access to the lock.
207 is currently owned and not recursed, and will return it unlocked.
225 on a per-instance basis.
226 The specified values will override the default
227 ones, but this can still be used passing, respectively,
228 .Dv LK_WMESG_DEFAULT ,
231 .Dv LK_TIMO_DEFAULT .
235 function switches the owner from the current thread to be
237 if the lock is already held.
240 .Fn lockmgr_printinfo
241 function prints debugging information about the lock.
242 It is used primarily by
248 function returns true if the lock is recursed, 0
253 function returns true if the lock has waiters, 0 otherwise.
257 function returns the status of the lock in relation to the current thread.
260 .Cd "options INVARIANTS"
262 .Cd "options INVARIANT_SUPPORT" ,
267 for the assertions specified in
269 and panics if they are not met.
270 One of the following assertions must be specified:
271 .Bl -tag -width ".Dv KA_UNLOCKED"
273 Assert that the current thread has either a shared or an exclusive lock on the
275 lock pointed to by the first argument.
277 Assert that the current thread has a shared lock on the
279 lock pointed to by the first argument.
281 Assert that the current thread has an exclusive lock on the
283 lock pointed to by the first argument.
285 Assert that the current thread has no lock on the
287 lock pointed to by the first argument.
290 In addition, one of the following optional assertions can be used with
297 .Bl -tag -width ".Dv KA_NOTRECURSED"
299 Assert that the current thread has a recursed lock on
301 .It Dv KA_NOTRECURSED
302 Assert that the current thread does not have a recursed lock on
311 functions return 0 on success and non-zero on failure.
316 .Bl -tag -width ".Dv LK_EXCLUSIVE"
318 An exclusive lock is held by the current thread.
320 An exclusive lock is held by someone other than the current thread.
322 A shared lock is held.
324 The lock is not held by anyone.
334 was requested and another thread had already requested a lock upgrade.
337 was set, and a sleep would have been required.
347 was set in the lock priority, and a signal was delivered during a sleep.
353 was set in the lock priority, a signal was delivered during a sleep,
354 and the system call is to be restarted.
355 .It Bq Er EWOULDBLOCK
356 a non-zero timeout was given, and the timeout expired.
369 must be held prior to calling
373 and will be returned unlocked.
375 Upgrade attempts that fail result in the loss of the lock that
377 Also, it is invalid to upgrade an
378 exclusive lock, and a
380 will be the result of trying.
392 This manual page was written by
393 .An Chad David Aq davidc@acns.ab.ca .