svn commit: r287780 - in head: share/man/man9 sys/kern sys/sys
Gleb Smirnoff
glebius at FreeBSD.org
Fri Sep 18 18:52:17 UTC 2015
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) \
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--
Totus tuus, Glebius.
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