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5 * The DragonFly Project. All rights reserved.
7 * This code contains ideas from software contributed to Berkeley by
8 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
9 * System project at Carnegie-Mellon University.
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21 * This product includes software developed by the University of
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36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * A number of third party programs #include <sys/lock.h> for no good
45 * reason. Don't actually include anything unless we are the kernel.
47 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)
49 #include <machine/lock.h>
50 #ifndef _SYS_THREAD_H_
51 #include <sys/thread.h> /* lwkt_token */
53 #ifndef _SYS_SPINLOCK_H_
54 #include <sys/spinlock.h>
58 * The general lock structure. Provides for multiple shared locks,
59 * upgrading from shared to exclusive, and sleeping until the lock
65 u_int lk_flags; /* see below */
66 int lk_count; /* -shared, +exclusive */
67 int lk_timo; /* maximum sleep time (for tsleep) */
68 const char *lk_wmesg; /* resource sleeping (for tsleep) */
69 struct thread *lk_lockholder; /* thread of excl lock holder */
71 const char *lk_filename;
72 const char *lk_lockername;
81 * Get one of many possible shared locks. If a process holding an
82 * exclusive lock requests a shared lock, the exclusive lock(s) will
83 * be downgraded to shared locks.
86 * Stop further shared locks, when they are cleared, grant a pending
87 * upgrade if it exists, then grant an exclusive lock. Only one exclusive
88 * lock may exist at a time, except that a process holding an exclusive
89 * lock may get additional exclusive locks if it explicitly sets the
90 * LK_CANRECURSE flag in the lock request, or if the LK_CANRECUSE flag
91 * was set when the lock was initialized.
94 * The process must hold a shared lock that it wants to have upgraded
95 * to an exclusive lock. Other processes may get exclusive access to
96 * the resource between the time that the upgrade is requested and the
97 * time that it is granted.
100 * the process must hold a shared lock that it wants to have upgraded
101 * to an exclusive lock. If the request succeeds, no other processes
102 * will have gotten exclusive access to the resource between the time
103 * that the upgrade is requested and the time that it is granted.
104 * However, if another process has already requested an upgrade, the
105 * request will fail (see error returns below).
108 * The process must hold an exclusive lock that it wants to have
109 * downgraded to a shared lock. If the process holds multiple (recursive)
110 * exclusive locks, they will all be downgraded to shared locks.
113 * Release one instance of a lock.
116 * The current exclusive lock holder can cancel any blocked lock requests,
117 * or any new requests, whos callers specified LK_CANCELABLE. They will
118 * receive a ENOLCK error code. Cancel beg/end does not stack.
120 * The cancel command stays in effect until the exclusive lock holder
121 * releases the last count on the lock or issues a LK_CANCEL_END command.
124 * The current exclusive lock holder can stop canceling new requests
125 * whos callers specify LK_CANCELABLE. The exclusive lock is maintained.
127 * Note that the last release of the exclusive lock will also
128 * automatically end cancel mode.
133 * LK_EXCLOTHER - return for lockstatus(). Used when another process
134 * holds the lock exclusively.
136 * These are flags that are passed to the lockmgr routine.
138 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */
139 #define LK_SHARED 0x00000001 /* shared lock */
140 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
141 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */
142 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */
143 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */
144 #define LK_RELEASE 0x00000006 /* release any type of lock */
145 #define LK_WAITUPGRADE 0x00000007
146 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */
147 #define LK_CANCEL_BEG 0x00000009 /* cancel other requests */
148 #define LK_CANCEL_END 0x0000000a /* stop canceling other requests */
151 * lk_count bit fields.
153 * Positive count is exclusive, negative count is shared. The count field
154 * must be large enough to accomodate all possible threads.
156 #define LKC_EXREQ 0x80000000 /* waiting for exclusive lock */
157 #define LKC_SHREQ 0x40000000 /* waiting for shared lock */
158 #define LKC_UPREQ 0x20000000 /* waiting for upgrade */
159 #define LKC_EXCL 0x10000000 /* exclusive (else shr or unlcoked) */
160 #define LKC_UPGRANT 0x08000000 /* upgrade granted */
161 #define LKC_CANCEL 0x04000000 /* cancel in effect */
162 #define LKC_MASK 0x03FFFFFF
165 * External lock flags.
167 * The first three flags may be set in lock_init to set their mode permanently,
168 * or passed in as arguments to the lock manager.
170 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */
171 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
172 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
173 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
174 #define LK_CANCELABLE 0x01000000 /* blocked caller can be canceled */
175 #define LK_TIMELOCK 0x02000000
176 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */
181 * Non-persistent external flags.
183 #define LK_FAILRECLAIM 0x00010000 /* vn_lock: allowed to fail on reclaim */
184 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
185 #define LK_UNUSED40000 0x00040000
186 #define LK_UNUSED80000 0x00080000
189 * Lock return status.
191 * Successfully obtained locks return 0. Locks will always succeed
192 * unless one of the following is true:
193 * LK_FORCEUPGRADE is requested and some other process has already
194 * requested a lock upgrade (returns EBUSY).
195 * LK_WAIT is set and a sleep would be required (returns EBUSY).
196 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
197 * PCATCH is set in lock priority and a signal arrives (returns
198 * either EINTR or ERESTART if system calls is to be restarted).
199 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
200 * A failed lock attempt always returns a non-zero error value. No lock
201 * is held after an error return (in particular, a failed LK_UPGRADE
202 * or LK_FORCEUPGRADE will have released its shared access lock).
206 * Indicator that no process holds exclusive lock
208 #define LK_KERNTHREAD ((struct thread *)-2)
209 #define LK_NOTHREAD ((struct thread *)-1)
213 void dumplockinfo(struct lock *lkp);
217 struct lock *la_lock;
222 #define LOCK_INITIALIZER(wmesg, timo, flags) \
224 .lk_flags = ((flags) & LK_EXTFLG_MASK), \
228 .lk_lockholder = LK_NOTHREAD \
231 void lockinit (struct lock *, const char *wmesg, int timo, int flags);
232 void lockreinit (struct lock *, const char *wmesg, int timo, int flags);
233 void lockuninit(struct lock *);
234 void lock_sysinit(struct lock_args *);
236 int debuglockmgr (struct lock *, u_int flags,
240 #define lockmgr(lockp, flags) \
241 debuglockmgr((lockp), (flags), "lockmgr", __FILE__, __LINE__)
243 int lockmgr (struct lock *, u_int flags);
245 void lockmgr_setexclusive_interlocked(struct lock *);
246 void lockmgr_clrexclusive_interlocked(struct lock *);
247 void lockmgr_kernproc (struct lock *);
248 void lockmgr_printinfo (struct lock *);
249 int lockstatus (struct lock *, struct thread *);
250 int lockowned (struct lock *);
251 int lockcount (struct lock *);
252 int lockcountnb (struct lock *);
254 #define LOCK_SYSINIT(name, lock, desc, flags) \
255 static struct lock_args name##_args = { \
260 SYSINIT(name##_lock_sysinit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \
261 lock_sysinit, &name##_args); \
262 SYSUNINIT(name##_lock_sysuninit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \
266 #endif /* _KERNEL || _KERNEL_STRUCTURES */
267 #endif /* _SYS_LOCK_H_ */