svn commit: r350641 - in releng/12.0/sys: kern sys
Gordon Tetlow
gordon at FreeBSD.org
Tue Aug 6 17:07:44 UTC 2019
Author: gordon
Date: Tue Aug 6 17:07:43 2019
New Revision: 350641
URL: https://svnweb.freebsd.org/changeset/base/350641
Log:
Fix incorrect locking in epoch(9).
Approved by: so
Security: FreeBSD-EN-19:14.epoch
Modified:
releng/12.0/sys/kern/subr_epoch.c
releng/12.0/sys/kern/subr_turnstile.c
releng/12.0/sys/sys/turnstile.h
Modified: releng/12.0/sys/kern/subr_epoch.c
==============================================================================
--- releng/12.0/sys/kern/subr_epoch.c Tue Aug 6 17:05:58 2019 (r350640)
+++ releng/12.0/sys/kern/subr_epoch.c Tue Aug 6 17:07:43 2019 (r350641)
@@ -325,24 +325,20 @@ epoch_block_handler_preempt(struct ck_epoch *global __
*/
critical_enter();
thread_unlock(td);
- owner = turnstile_lock(ts, &lock);
- /*
- * The owner pointer indicates that the lock succeeded. Only
- * in case we hold the lock and the turnstile we locked is still
- * the one that curwaittd is blocked on can we continue. Otherwise
- * The turnstile pointer has been changed out from underneath
- * us, as in the case where the lock holder has signalled curwaittd,
- * and we need to continue.
- */
- if (owner != NULL && ts == curwaittd->td_blocked) {
- MPASS(TD_IS_INHIBITED(curwaittd) && TD_ON_LOCK(curwaittd));
- critical_exit();
- turnstile_wait(ts, owner, curwaittd->td_tsqueue);
- counter_u64_add(turnstile_count, 1);
- thread_lock(td);
- return;
- } else if (owner != NULL)
+
+ if (turnstile_lock(ts, &lock, &owner)) {
+ if (ts == curwaittd->td_blocked) {
+ MPASS(TD_IS_INHIBITED(curwaittd) &&
+ TD_ON_LOCK(curwaittd));
+ critical_exit();
+ turnstile_wait(ts, owner,
+ curwaittd->td_tsqueue);
+ counter_u64_add(turnstile_count, 1);
+ thread_lock(td);
+ return;
+ }
turnstile_unlock(ts, lock);
+ }
thread_lock(td);
critical_exit();
KASSERT(td->td_locks == locksheld,
Modified: releng/12.0/sys/kern/subr_turnstile.c
==============================================================================
--- releng/12.0/sys/kern/subr_turnstile.c Tue Aug 6 17:05:58 2019 (r350640)
+++ releng/12.0/sys/kern/subr_turnstile.c Tue Aug 6 17:07:43 2019 (r350641)
@@ -566,24 +566,26 @@ turnstile_trywait(struct lock_object *lock)
return (ts);
}
-struct thread *
-turnstile_lock(struct turnstile *ts, struct lock_object **lockp)
+bool
+turnstile_lock(struct turnstile *ts, struct lock_object **lockp,
+ struct thread **tdp)
{
struct turnstile_chain *tc;
struct lock_object *lock;
if ((lock = ts->ts_lockobj) == NULL)
- return (NULL);
+ return (false);
tc = TC_LOOKUP(lock);
mtx_lock_spin(&tc->tc_lock);
mtx_lock_spin(&ts->ts_lock);
if (__predict_false(lock != ts->ts_lockobj)) {
mtx_unlock_spin(&tc->tc_lock);
mtx_unlock_spin(&ts->ts_lock);
- return (NULL);
+ return (false);
}
*lockp = lock;
- return (ts->ts_owner);
+ *tdp = ts->ts_owner;
+ return (true);
}
void
Modified: releng/12.0/sys/sys/turnstile.h
==============================================================================
--- releng/12.0/sys/sys/turnstile.h Tue Aug 6 17:05:58 2019 (r350640)
+++ releng/12.0/sys/sys/turnstile.h Tue Aug 6 17:07:43 2019 (r350641)
@@ -100,7 +100,8 @@ int turnstile_signal(struct turnstile *, int);
struct turnstile *turnstile_trywait(struct lock_object *);
void turnstile_unpend(struct turnstile *);
void turnstile_wait(struct turnstile *, struct thread *, int);
-struct thread *turnstile_lock(struct turnstile *, struct lock_object **);
+bool turnstile_lock(struct turnstile *, struct lock_object **,
+ struct thread **);
void turnstile_unlock(struct turnstile *, struct lock_object *);
void turnstile_assert(struct turnstile *);
#endif /* _KERNEL */
More information about the svn-src-all
mailing list