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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;
79 * LK_SHARED - get one of many possible shared locks. If a process
80 * holding an exclusive lock requests a shared lock, the exclusive
81 * lock(s) will be downgraded to shared locks.
82 * LK_EXCLUSIVE - stop further shared locks, when they are cleared,
83 * grant a pending upgrade if it exists, then grant an exclusive
84 * lock. Only one exclusive lock may exist at a time, except that
85 * a process holding an exclusive lock may get additional exclusive
86 * locks if it explicitly sets the LK_CANRECURSE flag in the lock
87 * request, or if the LK_CANRECUSE flag was set when the lock was
89 * LK_UPGRADE - the process must hold a shared lock that it wants to
90 * have upgraded to an exclusive lock. Other processes may get
91 * exclusive access to the resource between the time that the upgrade
92 * is requested and the time that it is granted.
93 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
94 * have upgraded to an exclusive lock. If the request succeeds, no
95 * other processes will have gotten exclusive access to the resource
96 * between the time that the upgrade is requested and the time that
97 * it is granted. However, if another process has already requested
98 * an upgrade, the request will fail (see error returns below).
99 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants
100 * to have downgraded to a shared lock. If the process holds multiple
101 * (recursive) exclusive locks, they will all be downgraded to shared
103 * LK_RELEASE - release one instance of a lock.
104 * LK_EXCLOTHER - return for lockstatus(). Used when another process
105 * holds the lock exclusively.
107 * These are flags that are passed to the lockmgr routine.
109 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */
110 #define LK_SHARED 0x00000001 /* shared lock */
111 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
112 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */
113 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */
114 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */
115 #define LK_RELEASE 0x00000006 /* release any type of lock */
116 #define LK_WAITUPGRADE 0x00000007
117 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */
120 * lk_count bit fields.
122 * Positive count is exclusive, negative count is shared.
124 #define LKC_EXREQ 0x80000000 /* waiting for exclusive lock */
125 #define LKC_SHREQ 0x40000000 /* waiting for shared lock */
126 #define LKC_UPREQ 0x20000000 /* waiting for upgrade */
127 #define LKC_EXCL 0x10000000 /* exclusive (else shr or unlcoked) */
128 #define LKC_UPGRANT 0x08000000 /* upgrade granted */
129 #define LKC_MASK 0x07FFFFFF
132 * External lock flags.
134 * The first three flags may be set in lock_init to set their mode permanently,
135 * or passed in as arguments to the lock manager.
137 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */
138 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
139 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
140 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
141 #define LK_UNUSED0080 0x00000080
142 #define LK_UNUSED0100x 0x01000000
143 #define LK_TIMELOCK 0x02000000
144 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */
149 * Non-persistent external flags.
151 #define LK_FAILRECLAIM 0x00010000 /* vn_lock: allowed to fail on reclaim */
152 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
153 #define LK_UNUSED40000 0x00040000
154 #define LK_UNUSED80000 0x00080000
157 * Lock return status.
159 * Successfully obtained locks return 0. Locks will always succeed
160 * unless one of the following is true:
161 * LK_FORCEUPGRADE is requested and some other process has already
162 * requested a lock upgrade (returns EBUSY).
163 * LK_WAIT is set and a sleep would be required (returns EBUSY).
164 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
165 * PCATCH is set in lock priority and a signal arrives (returns
166 * either EINTR or ERESTART if system calls is to be restarted).
167 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
168 * A failed lock attempt always returns a non-zero error value. No lock
169 * is held after an error return (in particular, a failed LK_UPGRADE
170 * or LK_FORCEUPGRADE will have released its shared access lock).
174 * Indicator that no process holds exclusive lock
176 #define LK_KERNTHREAD ((struct thread *)-2)
177 #define LK_NOTHREAD ((struct thread *)-1)
181 void dumplockinfo(struct lock *lkp);
185 struct lock *la_lock;
190 void lockinit (struct lock *, const char *wmesg, int timo, int flags);
191 void lockreinit (struct lock *, const char *wmesg, int timo, int flags);
192 void lockuninit(struct lock *);
193 void lock_sysinit(struct lock_args *);
195 int debuglockmgr (struct lock *, u_int flags,
199 #define lockmgr(lockp, flags) \
200 debuglockmgr((lockp), (flags), "lockmgr", __FILE__, __LINE__)
202 int lockmgr (struct lock *, u_int flags);
204 void lockmgr_setexclusive_interlocked(struct lock *);
205 void lockmgr_clrexclusive_interlocked(struct lock *);
206 void lockmgr_kernproc (struct lock *);
207 void lockmgr_printinfo (struct lock *);
208 int lockstatus (struct lock *, struct thread *);
209 int lockowned (struct lock *);
210 int lockcount (struct lock *);
211 int lockcountnb (struct lock *);
213 #define LOCK_SYSINIT(name, lock, desc, flags) \
214 static struct lock_args name##_args = { \
219 SYSINIT(name##_lock_sysinit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \
220 lock_sysinit, &name##_args); \
221 SYSUNINIT(name##_lock_sysuninit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \
225 #endif /* _KERNEL || _KERNEL_STRUCTURES */
226 #endif /* _SYS_LOCK_H_ */