Author: rrs
Date: Tue Mar 31 00:18:00 2015
New Revision: 280872
URL: https://svnweb.freebsd.org/changeset/base/280872
Log:
Adopt jhb's suggested changes, updated comments and callout_migration() moving
to kern/kern_timeout.c
This does *not* address his -1 -> NOCPU comment.
Sponsored by: Netflix Inc.
Modified:
head/sys/kern/kern_timeout.c
head/sys/sys/callout.h
Modified: head/sys/kern/kern_timeout.c
==============================================================================
--- head/sys/kern/kern_timeout.c Tue Mar 31 00:15:27 2015
(r280871)
+++ head/sys/kern/kern_timeout.c Tue Mar 31 00:18:00 2015
(r280872)
@@ -167,6 +167,8 @@ struct callout_cpu {
char cc_ktr_event_name[20];
};
+#define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION)
+
#define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr
#define cc_exec_next(cc) cc->cc_next
#define cc_exec_cancel(cc, dir)
cc->cc_exec_entity[dir].cc_cancel
Modified: head/sys/sys/callout.h
==============================================================================
--- head/sys/sys/callout.h Tue Mar 31 00:15:27 2015 (r280871)
+++ head/sys/sys/callout.h Tue Mar 31 00:18:00 2015 (r280872)
@@ -68,18 +68,18 @@ struct callout_handle {
* field is the one that caller operations that may, or may not have
* a lock touches i.e. callout_deactivate(). The other, the c_iflags,
* is the internal flags that *must* be kept correct on which the
- * callout system depend on i.e. callout_migrating() & callout_pending(),
- * these are used internally by the callout system to determine which
- * list and other critical internal state. Callers *should not* use the
- * c_flags field directly but should use the macros!
+ * callout system depend on e.g. callout_pending().
+ * The c_iflag is used internally by the callout system to determine which
+ * list the callout is on and track internal state. Callers *should not*
+ * use the c_flags field directly but should use the macros provided.
*
- * If the caller wants to keep the c_flags field sane they
- * should init with a mutex *or* if using the older
- * mpsafe option, they *must* lock there own lock
- * before calling callout_deactivate().
+ * The c_iflags field holds internal flags that are protected by internal
+ * locks of the callout subsystem. The c_flags field holds external flags.
+ * The caller must hold its own lock while manipulating or reading external
+ * flags via callout_active(), callout_deactivate(), callout_reset*(), or
+ * callout_stop() to avoid races.
*/
#define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE)
-#define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION)
#define callout_deactivate(c) ((c)->c_flags &= ~CALLOUT_ACTIVE)
#define callout_drain(c) _callout_stop_safe(c, 1)
void callout_init(struct callout *, int);
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