Fix cv_waiters wraparound bug
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Authored by markj on Jan 8 2016, 12:36 AM.

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benno
jhb

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rS293458: Prevent cv_waiters wraparound.

Summary

This is another attempt to fix the issue described in r282971, which was
reverted in r283250. Rather than eliminating cv_waiters entirely, cap
its value at INT_MAX and modify cv_signal() to handle that case
appropriately. In particular, this lets us avoid looking up the
sleepqueue on every call to cv_signal().

Diff Detail

Repository

rS FreeBSD src repository - subversion

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markj updated this revision to Diff 12022.Jan 8 2016, 12:36 AM

markj retitled this revision from to Fix cv_waiters wraparound bug.

markj edited the test plan for this revision. (Show Details)

markj updated this object.

Herald added a subscriber: imp. · View Herald TranscriptJan 8 2016, 12:36 AM

markj added reviewers: jhb, benno.Jan 8 2016, 12:39 AM

Don't assert cv_waiters == 0 in cv_destroy().

It may be non-zero even with zero sleepers, since threads don't
decrement it when they wake up.

jhb accepted this revision.Jan 8 2016, 6:56 PM

jhb edited edge metadata.

This revision is now accepted and ready to land.Jan 8 2016, 6:56 PM

Closed by commit rS293458: Prevent cv_waiters wraparound. (authored by markj). · Explain WhyJan 9 2016, 1:56 AM

This revision was automatically updated to reflect the committed changes.

Revision Contents
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Path

Size

head/

sys/

kern/

kern_condvar.c

33 lines

Diff 12067

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head/sys/kern/kern_condvar.c

	Show First 20 Lines • Show All 1,950 Lines • ▼ Show 20 Lines
	{			{
	LIST_HEAD(, rctl_rule_link) newrules;			LIST_HEAD(, rctl_rule_link) newrules;
	struct rctl_rule_link link, newlink;			struct rctl_rule_link link, newlink;
	struct uidinfo *newuip;			struct uidinfo *newuip;
	struct loginclass *newlc;			struct loginclass *newlc;
	struct prison_racct *newprr;			struct prison_racct *newprr;
	int rulecnt, i;			int rulecnt, i;

	ASSERT_RACCT_ENABLED();			if (!racct_enable)
				return;

				PROC_LOCK_ASSERT(p, MA_NOTOWNED);

	newuip = newcred->cr_ruidinfo;			newuip = newcred->cr_ruidinfo;
	newlc = newcred->cr_loginclass;			newlc = newcred->cr_loginclass;
	newprr = newcred->cr_prison->pr_prison_racct;			newprr = newcred->cr_prison->pr_prison_racct;

	LIST_INIT(&newrules);			LIST_INIT(&newrules);

	again:			again:
	/*			/*
	* First, count the rules that apply to the process with new			* First, count the rules that apply to the process with new
	* credentials.			* credentials.
	*/			*/
	rulecnt = 0;			rulecnt = 0;
	▲ Show 20 Lines • Show All 263 Lines • Show Last 20 Lines

Fix cv_waiters wraparound bugClosedPublicActions