Author: hselasky Date: Mon Sep 14 10:52:26 2015 New Revision: 287780 URL: https://svnweb.freebsd.org/changeset/base/287780
Log: Implement callout_drain_async(), inspired by the projects/hps_head branch. This function is used to drain a callout via a callback instead of blocking the caller until the drain is complete. Refer to the callout_drain_async() manual page for a detailed description. Limitation: If a lock is used with the callout, the callout can only be drained asynchronously one time unless the callout_init_mtx() function is called again. This limitation is not present in projects/hps_head and will require more invasive changes to the timeout code, which was not in the scope of this patch. Differential Revision: https://reviews.freebsd.org/D3521 Reviewed by: wblock MFC after: 1 month Modified: head/share/man/man9/Makefile head/share/man/man9/timeout.9 head/sys/kern/kern_timeout.c head/sys/sys/_callout.h head/sys/sys/callout.h Modified: head/share/man/man9/Makefile ============================================================================== --- head/share/man/man9/Makefile Mon Sep 14 10:28:47 2015 (r287779) +++ head/share/man/man9/Makefile Mon Sep 14 10:52:26 2015 (r287780) @@ -1641,6 +1641,7 @@ MLINKS+=timeout.9 callout.9 \ timeout.9 callout_active.9 \ timeout.9 callout_deactivate.9 \ timeout.9 callout_drain.9 \ + timeout.9 callout_drain_async.9 \ timeout.9 callout_handle_init.9 \ timeout.9 callout_init.9 \ timeout.9 callout_init_mtx.9 \ Modified: head/share/man/man9/timeout.9 ============================================================================== --- head/share/man/man9/timeout.9 Mon Sep 14 10:28:47 2015 (r287779) +++ head/share/man/man9/timeout.9 Mon Sep 14 10:52:26 2015 (r287780) @@ -36,6 +36,7 @@ .Nm callout_active , .Nm callout_deactivate , .Nm callout_drain , +.Nm callout_drain_async , .Nm callout_handle_init , .Nm callout_init , .Nm callout_init_mtx , @@ -70,6 +71,8 @@ typedef void timeout_t (void *); .Fn callout_deactivate "struct callout *c" .Ft int .Fn callout_drain "struct callout *c" +.Ft int +.Fn callout_drain_async "struct callout *c" "callout_func_t *fn" "void *arg" .Ft void .Fn callout_handle_init "struct callout_handle *handle" .Bd -literal @@ -264,6 +267,24 @@ fully stopped before .Fn callout_drain returns. .Pp +The function +.Fn callout_drain_async +is non-blocking and works the same as the +.Fn callout_stop +function. +When this function returns non-zero, do not call it again until the callback function given by +.Fa fn +has been called with argument +.Fa arg . +Only one of +.Fn callout_drain +or +.Fn callout_drain_async +should be called at a time to drain a callout. +If this function returns zero, it is safe to free the callout structure pointed to by the +.Fa c +argument immediately. +.Pp The .Fn callout_reset and Modified: head/sys/kern/kern_timeout.c ============================================================================== --- head/sys/kern/kern_timeout.c Mon Sep 14 10:28:47 2015 (r287779) +++ head/sys/kern/kern_timeout.c Mon Sep 14 10:52:26 2015 (r287780) @@ -1145,6 +1145,45 @@ callout_schedule(struct callout *c, int } int +callout_drain_async(struct callout *c, callout_func_t *func, void *arg) +{ + struct callout_cpu *cc; + struct lock_class *class; + int retval; + int direct; + + /* stop callout */ + callout_stop(c); + + /* check if callback is being called */ + cc = callout_lock(c); + if (c->c_iflags & CALLOUT_DIRECT) { + direct = 1; + } else { + direct = 0; + } + retval = (cc_exec_curr(cc, direct) == c); + + /* drop locks, if any */ + if (retval && c->c_lock != NULL && + c->c_lock != &Giant.lock_object) { + /* ensure we are properly locked */ + class = LOCK_CLASS(c->c_lock); + class->lc_assert(c->c_lock, LA_XLOCKED); + /* the final callback should not be called locked */ + c->c_lock = NULL; + c->c_iflags |= CALLOUT_RETURNUNLOCKED; + } + CC_UNLOCK(cc); + + /* check if we should queue final callback */ + if (retval) + callout_reset(c, 1, func, arg); + + return (retval); +} + +int _callout_stop_safe(struct callout *c, int safe) { struct callout_cpu *cc, *old_cc; Modified: head/sys/sys/_callout.h ============================================================================== --- head/sys/sys/_callout.h Mon Sep 14 10:28:47 2015 (r287779) +++ head/sys/sys/_callout.h Mon Sep 14 10:52:26 2015 (r287780) @@ -46,6 +46,8 @@ LIST_HEAD(callout_list, callout); SLIST_HEAD(callout_slist, callout); TAILQ_HEAD(callout_tailq, callout); +typedef void callout_func_t(void *); + struct callout { union { LIST_ENTRY(callout) le; Modified: head/sys/sys/callout.h ============================================================================== --- head/sys/sys/callout.h Mon Sep 14 10:28:47 2015 (r287779) +++ head/sys/sys/callout.h Mon Sep 14 10:52:26 2015 (r287780) @@ -82,6 +82,7 @@ struct callout_handle { #define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE) #define callout_deactivate(c) ((c)->c_flags &= ~CALLOUT_ACTIVE) #define callout_drain(c) _callout_stop_safe(c, 1) +int callout_drain_async(struct callout *, callout_func_t *, void *); void callout_init(struct callout *, int); void _callout_init_lock(struct callout *, struct lock_object *, int); #define callout_init_mtx(c, mtx, flags) \ _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
