Date: Fri, 18 Sep 2015 21:52:07 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Hans Petter Selasky <hselasky@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r287780 - in head: share/man/man9 sys/kern sys/sys Message-ID: <20150918185207.GF1023@FreeBSD.org> In-Reply-To: <201509141052.t8EAqRWf008293@repo.freebsd.org> References: <201509141052.t8EAqRWf008293@repo.freebsd.org>
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Hans, on behalf of core, I ask you to revert this change due to lack of review and due to previous issues in this area. On Mon, Sep 14, 2015 at 10:52:27AM +0000, Hans Petter Selasky wrote: H> Author: hselasky H> Date: Mon Sep 14 10:52:26 2015 H> New Revision: 287780 H> URL: https://svnweb.freebsd.org/changeset/base/287780 H> H> Log: H> Implement callout_drain_async(), inspired by the projects/hps_head H> branch. H> H> This function is used to drain a callout via a callback instead of H> blocking the caller until the drain is complete. Refer to the H> callout_drain_async() manual page for a detailed description. H> H> Limitation: If a lock is used with the callout, the callout can only H> be drained asynchronously one time unless the callout_init_mtx() H> function is called again. This limitation is not present in H> projects/hps_head and will require more invasive changes to the H> timeout code, which was not in the scope of this patch. H> H> Differential Revision: https://reviews.freebsd.org/D3521 H> Reviewed by: wblock H> MFC after: 1 month H> H> Modified: H> head/share/man/man9/Makefile H> head/share/man/man9/timeout.9 H> head/sys/kern/kern_timeout.c H> head/sys/sys/_callout.h H> head/sys/sys/callout.h H> H> Modified: head/share/man/man9/Makefile H> ============================================================================== H> --- head/share/man/man9/Makefile Mon Sep 14 10:28:47 2015 (r287779) H> +++ head/share/man/man9/Makefile Mon Sep 14 10:52:26 2015 (r287780) H> @@ -1641,6 +1641,7 @@ MLINKS+=timeout.9 callout.9 \ H> timeout.9 callout_active.9 \ H> timeout.9 callout_deactivate.9 \ H> timeout.9 callout_drain.9 \ H> + timeout.9 callout_drain_async.9 \ H> timeout.9 callout_handle_init.9 \ H> timeout.9 callout_init.9 \ H> timeout.9 callout_init_mtx.9 \ H> H> Modified: head/share/man/man9/timeout.9 H> ============================================================================== H> --- head/share/man/man9/timeout.9 Mon Sep 14 10:28:47 2015 (r287779) H> +++ head/share/man/man9/timeout.9 Mon Sep 14 10:52:26 2015 (r287780) H> @@ -36,6 +36,7 @@ H> .Nm callout_active , H> .Nm callout_deactivate , H> .Nm callout_drain , H> +.Nm callout_drain_async , H> .Nm callout_handle_init , H> .Nm callout_init , H> .Nm callout_init_mtx , H> @@ -70,6 +71,8 @@ typedef void timeout_t (void *); H> .Fn callout_deactivate "struct callout *c" H> .Ft int H> .Fn callout_drain "struct callout *c" H> +.Ft int H> +.Fn callout_drain_async "struct callout *c" "callout_func_t *fn" "void *arg" H> .Ft void H> .Fn callout_handle_init "struct callout_handle *handle" H> .Bd -literal H> @@ -264,6 +267,24 @@ fully stopped before H> .Fn callout_drain H> returns. H> .Pp H> +The function H> +.Fn callout_drain_async H> +is non-blocking and works the same as the H> +.Fn callout_stop H> +function. H> +When this function returns non-zero, do not call it again until the callback function given by H> +.Fa fn H> +has been called with argument H> +.Fa arg . H> +Only one of H> +.Fn callout_drain H> +or H> +.Fn callout_drain_async H> +should be called at a time to drain a callout. H> +If this function returns zero, it is safe to free the callout structure pointed to by the H> +.Fa c H> +argument immediately. H> +.Pp H> The H> .Fn callout_reset H> and H> H> Modified: head/sys/kern/kern_timeout.c H> ============================================================================== H> --- head/sys/kern/kern_timeout.c Mon Sep 14 10:28:47 2015 (r287779) H> +++ head/sys/kern/kern_timeout.c Mon Sep 14 10:52:26 2015 (r287780) H> @@ -1145,6 +1145,45 @@ callout_schedule(struct callout *c, int H> } H> H> int H> +callout_drain_async(struct callout *c, callout_func_t *func, void *arg) H> +{ H> + struct callout_cpu *cc; H> + struct lock_class *class; H> + int retval; H> + int direct; H> + H> + /* stop callout */ H> + callout_stop(c); H> + H> + /* check if callback is being called */ H> + cc = callout_lock(c); H> + if (c->c_iflags & CALLOUT_DIRECT) { H> + direct = 1; H> + } else { H> + direct = 0; H> + } H> + retval = (cc_exec_curr(cc, direct) == c); H> + H> + /* drop locks, if any */ H> + if (retval && c->c_lock != NULL && H> + c->c_lock != &Giant.lock_object) { H> + /* ensure we are properly locked */ H> + class = LOCK_CLASS(c->c_lock); H> + class->lc_assert(c->c_lock, LA_XLOCKED); H> + /* the final callback should not be called locked */ H> + c->c_lock = NULL; H> + c->c_iflags |= CALLOUT_RETURNUNLOCKED; H> + } H> + CC_UNLOCK(cc); H> + H> + /* check if we should queue final callback */ H> + if (retval) H> + callout_reset(c, 1, func, arg); H> + H> + return (retval); H> +} H> + H> +int H> _callout_stop_safe(struct callout *c, int safe) H> { H> struct callout_cpu *cc, *old_cc; H> H> Modified: head/sys/sys/_callout.h H> ============================================================================== H> --- head/sys/sys/_callout.h Mon Sep 14 10:28:47 2015 (r287779) H> +++ head/sys/sys/_callout.h Mon Sep 14 10:52:26 2015 (r287780) H> @@ -46,6 +46,8 @@ LIST_HEAD(callout_list, callout); H> SLIST_HEAD(callout_slist, callout); H> TAILQ_HEAD(callout_tailq, callout); H> H> +typedef void callout_func_t(void *); H> + H> struct callout { H> union { H> LIST_ENTRY(callout) le; H> H> Modified: head/sys/sys/callout.h H> ============================================================================== H> --- head/sys/sys/callout.h Mon Sep 14 10:28:47 2015 (r287779) H> +++ head/sys/sys/callout.h Mon Sep 14 10:52:26 2015 (r287780) H> @@ -82,6 +82,7 @@ struct callout_handle { H> #define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE) H> #define callout_deactivate(c) ((c)->c_flags &= ~CALLOUT_ACTIVE) H> #define callout_drain(c) _callout_stop_safe(c, 1) H> +int callout_drain_async(struct callout *, callout_func_t *, void *); H> void callout_init(struct callout *, int); H> void _callout_init_lock(struct callout *, struct lock_object *, int); H> #define callout_init_mtx(c, mtx, flags) \ H> _______________________________________________ H> svn-src-all@freebsd.org mailing list H> https://lists.freebsd.org/mailman/listinfo/svn-src-all H> To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org" -- Totus tuus, Glebius.
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