Author: hselasky
Date: Wed Sep 2 09:44:00 2020
New Revision: 365237
URL: https://svnweb.freebsd.org/changeset/base/365237
Log:
Micro optimise _callout_stop_safe() by removing dead code.
The CS_DRAIN flag cannot be set at the same time like the async-drain function
pointer is set. These are orthogonal features. Assert this at the beginning
of the function.
Before:
if (flags & CS_DRAIN) {
/* FALLTHROUGH */
} else if (xxx) {
return yyy;
}
if (drain) {
zzz = drain;
}
After:
if (flags & CS_DRAIN) {
/* FALLTHROUGH */
} else if (xxx) {
return yyy;
} else {
if (drain) {
zzz = drain;
}
}
Reviewed by: markj@
Tested by: callout_test
Differential Revision: https://reviews.freebsd.org/D26285
MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking
Modified:
head/sys/kern/kern_timeout.c
Modified: head/sys/kern/kern_timeout.c
==============================================================================
--- head/sys/kern/kern_timeout.c Wed Sep 2 09:20:40 2020
(r365236)
+++ head/sys/kern/kern_timeout.c Wed Sep 2 09:44:00 2020
(r365237)
@@ -1075,6 +1075,9 @@ _callout_stop_safe(struct callout *c, int flags, callo
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
"calling %s", __func__);
+ KASSERT((flags & CS_DRAIN) == 0 || drain == NULL,
+ ("Cannot set drain callback and CS_DRAIN flag at the same time"));
+
/*
* Some old subsystems don't hold Giant while running a callout_stop(),
* so just discard this check for the moment.
@@ -1270,11 +1273,12 @@ again:
}
CC_UNLOCK(cc);
return ((flags & CS_EXECUTING) != 0);
- }
- CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
- c, c->c_func, c->c_arg);
- if (drain) {
- cc_exec_drain(cc, direct) = drain;
+ } else {
+ CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
+ c, c->c_func, c->c_arg);
+ if (drain) {
+ cc_exec_drain(cc, direct) = drain;
+ }
}
KASSERT(!sq_locked, ("sleepqueue chain still locked"));
cancelled = ((flags & CS_EXECUTING) != 0);
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