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5 * by Matthew Dillon <dillon@backplane.com>
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69 #ifndef _SYS_CALLOUT_H_
70 #define _SYS_CALLOUT_H_
73 #include <sys/queue.h>
78 #ifndef _CPU_ATOMIC_H_
79 #include <machine/atomic.h>
82 SLIST_HEAD(callout_list, callout);
83 TAILQ_HEAD(callout_tailq, callout);
86 * Callwheel linkages are only adjusted on the target cpu. The target
87 * cpu can only be [re]assigned when the IPI_MASK and PENDING bits are
90 * callout_reset() and callout_stop() are always synchronous and will
91 * interlock against a running callout as well as reassign the callout
92 * to the current cpu. The caller might block, and a deadlock is possible
93 * if the caller does not use callout_init_lk() or is not careful with
94 * locks acquired in the callout function.
96 * Programers should note that our lockmgr locks have a cancelation feature
97 * which can be used to avoid deadlocks. callout_init_lk() also uses this
100 * callout_deactivate() is asynchronous and will not interlock against
101 * anything. Deactivation does not dequeue a callout, it simply prevents
102 * its function from being executed.
106 SLIST_ENTRY(callout) sle;
107 TAILQ_ENTRY(callout) tqe;
109 int c_time; /* match tick on event */
110 int c_load; /* load value for reset ipi */
111 void *c_arg; /* function argument */
112 void (*c_func) (void *); /* function to call */
113 int c_flags; /* state of this entry */
114 int c_lineno; /* debugging */
115 struct lock *c_lk; /* auto-lock */
116 const char *c_ident; /* debugging */
120 * ACTIVE - If cleared this the callout is prevented from issuing its
121 * callback. The callout remains on its timer queue.
123 * PENDING - Indicates the callout is on a particular cpu's timer queue.
124 * Also locks the cpu owning the callout.
126 * MPSAFE - Indicates the callout does not need the MP lock (most
127 * callouts are flagged this way).
131 * EXECUTED - Set prior to function dispatch, cleared by callout_reset(),
132 * cleared and (prior value) returned by callout_stop_sync().
134 * WAITING - Used for tsleep/wakeup blocking, primarily for
137 * IPI_MASK - Counts pending IPIs. Also locks the cpu owning the callout.
139 * CPU_MASK - Currently assigned cpu. Only valid when at least one bit
140 * in ARMED_MASK is set.
143 #define CALLOUT_ACTIVE 0x80000000 /* quick [de]activation flag */
144 #define CALLOUT_PENDING 0x40000000 /* callout is on callwheel */
145 #define CALLOUT_MPSAFE 0x20000000 /* callout does not need the BGL */
146 #define CALLOUT_DID_INIT 0x10000000 /* safety check */
147 #define CALLOUT_AUTOLOCK 0x08000000 /* auto locking / cancel feature */
148 #define CALLOUT_WAITING 0x04000000 /* interlocked waiter */
149 #define CALLOUT_EXECUTED 0x02000000 /* (generates stop status) */
150 #define CALLOUT_UNUSED01 0x01000000
151 #define CALLOUT_IPI_MASK 0x00000FFF /* count operations in prog */
152 #define CALLOUT_CPU_MASK 0x00FFF000 /* cpu assignment */
154 #define CALLOUT_ARMED_MASK (CALLOUT_PENDING | CALLOUT_IPI_MASK)
156 #define CALLOUT_FLAGS_TO_CPU(flags) (((flags) & CALLOUT_CPU_MASK) >> 12)
157 #define CALLOUT_CPU_TO_FLAGS(cpuid) ((cpuid) << 12)
160 * WARNING! The caller is responsible for stabilizing the callout state,
161 * our suggestion is to either manage the callout on the same cpu
162 * or to use the callout_init_lk() feature and hold the lock while
163 * making callout_*() calls. The lock will be held automatically
164 * by the callout wheel for any call-back and the callout wheel
165 * will handle any callout_stop() deadlocks properly.
167 * active - Returns activation status. This bit is set by callout_reset*()
168 * and will only be cleared by an explicit callout_deactivate()
169 * or callout_stop(). A function dispatch does not clear this
170 * bit. In addition, a callout_reset() to another cpu is
171 * asynchronous and may not immediately re-set this bit.
173 * deactivate - Disarm the callout, preventing it from being executed if it
174 * is queued or the queueing operation is in-flight. Has no
175 * effect if the callout has already been dispatched. Does not
176 * dequeue the callout. Does not affect the status returned
179 * Not serialized, caller must be careful when racing a new
180 * callout_reset() that might be issued by the callback, which
181 * will re-arm the callout.
183 * callout_reset() must be called to reactivate the callout.
185 * pending - Only useful for same-cpu callouts, indicates that the callout
186 * is pending on the callwheel or that a callout_reset() ipi
187 * is (probably) in-flight. Can also false-positive on
188 * callout_stop() IPIs.
190 #define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE)
192 #define callout_deactivate(c) atomic_clear_int(&(c)->c_flags, CALLOUT_ACTIVE)
194 #define callout_pending(c) ((c)->c_flags & CALLOUT_ARMED_MASK)
201 void hardclock_softtick(struct globaldata *);
202 void callout_init (struct callout *);
203 void callout_init_mp (struct callout *);
204 void callout_init_lk (struct callout *, struct lock *);
205 void callout_initd (struct callout *, const char *, int);
206 void callout_initd_mp (struct callout *, const char *, int);
207 void callout_initd_lk (struct callout *, struct lock *, const char *, int);
208 void callout_reset (struct callout *, int, void (*)(void *), void *);
209 int callout_stop (struct callout *);
210 void callout_stop_async (struct callout *);
211 int callout_stop_sync (struct callout *);
212 void callout_terminate (struct callout *);
213 void callout_reset_bycpu (struct callout *, int, void (*)(void *), void *,
216 #define callout_drain(x) callout_stop_sync(x)
218 #define CALLOUT_DEBUG
220 #define callout_init(co) callout_initd(co, __FILE__, __LINE__)
221 #define callout_init_mp(co) callout_initd_mp(co, __FILE__, __LINE__)
222 #define callout_init_lk(co, lk) callout_initd_lk(co, lk, __FILE__, __LINE__)
227 #endif /* _SYS_CALLOUT_H_ */