Author: kib
Date: Thu Aug 25 19:15:02 2016
New Revision: 304812
URL: https://svnweb.freebsd.org/changeset/base/304812
Log:
In both do_rw_wrlock() and do_rw_rdlock() after r304808, do not
obliterate possible error from sleep with errors from
umtxq_check_susp(), when looping to clear URWLOCK_{READ,WRITE}_WAITERS.
Noted and reviewed by: vangyzen
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/kern/kern_umtx.c
Modified: head/sys/kern/kern_umtx.c
==============================================================================
--- head/sys/kern/kern_umtx.c Thu Aug 25 17:30:00 2016 (r304811)
+++ head/sys/kern/kern_umtx.c Thu Aug 25 19:15:02 2016 (r304812)
@@ -2609,7 +2609,7 @@ do_rw_rdlock(struct thread *td, struct u
uint32_t flags, wrflags;
int32_t state, oldstate;
int32_t blocked_readers;
- int error, rv;
+ int error, error1, rv;
uq = td->td_umtxq;
error = fueword32(&rwlock->rw_flags, &flags);
@@ -2758,9 +2758,12 @@ sleep:
if (oldstate == state)
break;
state = oldstate;
- error = umtxq_check_susp(td);
- if (error != 0)
+ error1 = umtxq_check_susp(td);
+ if (error1 != 0) {
+ if (error == 0)
+ error = error1;
break;
+ }
}
}
@@ -2783,7 +2786,7 @@ do_rw_wrlock(struct thread *td, struct u
int32_t state, oldstate;
int32_t blocked_writers;
int32_t blocked_readers;
- int error, rv;
+ int error, error1, rv;
uq = td->td_umtxq;
error = fueword32(&rwlock->rw_flags, &flags);
@@ -2929,14 +2932,17 @@ sleep:
if (oldstate == state)
break;
state = oldstate;
- error = umtxq_check_susp(td);
+ error1 = umtxq_check_susp(td);
/*
* We are leaving the URWLOCK_WRITE_WAITERS
* behind, but this should not harm the
* correctness.
*/
- if (error != 0)
+ if (error1 != 0) {
+ if (error == 0)
+ error = error1;
break;
+ }
}
rv = fueword32(&rwlock->rw_blocked_readers,
&blocked_readers);
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