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GNU C Library master sources branch master updated. glibc-2.21-435-gb634486
- From: torvald at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 4 Jun 2015 16:02:18 -0000
- Subject: GNU C Library master sources branch master updated. glibc-2.21-435-gb634486
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=b634486d57a14b53f1cfcf739e41ddf826e51977
commit b634486d57a14b53f1cfcf739e41ddf826e51977
Author: Torvald Riegel <triegel@redhat.com>
Date: Tue Apr 28 23:24:36 2015 +0200
Fix missing wake-ups in pthread_rwlock_rdlock.
This adds wake-ups that would be missing if assuming that for a
non-writer-preferring rwlock, if one thread has acquired a rdlock and
does not release it, another thread will eventually acquire a rdlock too
despite concurrent write lock acquisition attempts. BZ 14958 is about
supporting this assumption. Strictly speaking, this isn't a valid
test case, but nonetheless worth supporting (see comment 7 of BZ 14958).
diff --git a/ChangeLog b/ChangeLog
index 423ccea..cd25f44 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,19 @@
2015-06-04 Torvald Riegel <triegel@redhat.com>
+ [BZ #14958]
+ * nptl/pthread_rwlock_rdlock.c (__pthread_rwlock_rdlock): Add missing
+ wake-up.
+ (__pthread_rwlock_rdlock_slow): Likewise.
+ * nptl/pthread_rwlock_timedrdlock.c (pthread_rwlock_timedrdlock):
+ Likewise.
+ * nptl/pthread_rwlock_tryrdlock.c (__pthread_rwlock_tryrdlock):
+ Likewise.
+ * nptl/pthread_rwlock_unlock.c (__pthread_rwlock_unlock): Add comments.
+ * nptl/tst-rwlock16.c: New file.
+ * nptl/Makefile (tests): Add new test.
+
+2015-06-04 Torvald Riegel <triegel@redhat.com>
+
[BZ #18324]
* nptl/pthread_rwlock_timedwrlock.c (pthread_rwlock_timedwrlock): Add
missing wake-up of readers.
diff --git a/NEWS b/NEWS
index f8ad875..00bde64 100644
--- a/NEWS
+++ b/NEWS
@@ -9,18 +9,18 @@ Version 2.22
* The following bugs are resolved with this release:
- 438, 4719, 6792, 13028, 13064, 14094, 14841, 14906, 15319, 15467, 15790,
- 15969, 16159, 16339, 16351, 16352, 16512, 16560, 16704, 16783, 16850,
- 17053, 17090, 17195, 17269, 17293, 17523, 17542, 17569, 17581, 17588,
- 17596, 17620, 17621, 17628, 17631, 17692, 17711, 17715, 17776, 17779,
- 17792, 17836, 17912, 17916, 17930, 17932, 17944, 17949, 17964, 17965,
- 17967, 17969, 17978, 17987, 17991, 17996, 17998, 17999, 18007, 18019,
- 18020, 18029, 18030, 18032, 18036, 18038, 18039, 18042, 18043, 18046,
- 18047, 18049, 18068, 18080, 18093, 18100, 18104, 18110, 18111, 18116,
- 18125, 18128, 18138, 18185, 18196, 18197, 18206, 18210, 18211, 18217,
- 18220, 18221, 18234, 18244, 18247, 18287, 18319, 18324, 18333, 18346,
- 18397, 18409, 18410, 18412, 18418, 18422, 18434, 18444, 18468, 18469,
- 18470.
+ 438, 4719, 6792, 13028, 13064, 14094, 14841, 14906, 14958, 15319, 15467,
+ 15790, 15969, 16159, 16339, 16351, 16352, 16512, 16560, 16704, 16783,
+ 16850, 17053, 17090, 17195, 17269, 17293, 17523, 17542, 17569, 17581,
+ 17588, 17596, 17620, 17621, 17628, 17631, 17692, 17711, 17715, 17776,
+ 17779, 17792, 17836, 17912, 17916, 17930, 17932, 17944, 17949, 17964,
+ 17965, 17967, 17969, 17978, 17987, 17991, 17996, 17998, 17999, 18007,
+ 18019, 18020, 18029, 18030, 18032, 18036, 18038, 18039, 18042, 18043,
+ 18046, 18047, 18049, 18068, 18080, 18093, 18100, 18104, 18110, 18111,
+ 18116, 18125, 18128, 18138, 18185, 18196, 18197, 18206, 18210, 18211,
+ 18217, 18220, 18221, 18234, 18244, 18247, 18287, 18319, 18324, 18333,
+ 18346, 18397, 18409, 18410, 18412, 18418, 18422, 18434, 18444, 18468,
+ 18469, 18470.
* Cache information can be queried via sysconf() function on s390 e.g. with
_SC_LEVEL1_ICACHE_SIZE as argument.
diff --git a/nptl/Makefile b/nptl/Makefile
index 62436ac..d58324d 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -231,7 +231,7 @@ tests = tst-typesizes \
tst-rwlock1 tst-rwlock2 tst-rwlock2a tst-rwlock3 tst-rwlock4 \
tst-rwlock5 tst-rwlock6 tst-rwlock7 tst-rwlock8 tst-rwlock9 \
tst-rwlock10 tst-rwlock11 tst-rwlock12 tst-rwlock13 tst-rwlock14 \
- tst-rwlock15 \
+ tst-rwlock15 tst-rwlock16 \
tst-once1 tst-once2 tst-once3 tst-once4 \
tst-key1 tst-key2 tst-key3 tst-key4 \
tst-sem1 tst-sem2 tst-sem3 tst-sem4 tst-sem5 tst-sem6 tst-sem7 \
diff --git a/nptl/pthread_rwlock_rdlock.c b/nptl/pthread_rwlock_rdlock.c
index 0edca65..004a386 100644
--- a/nptl/pthread_rwlock_rdlock.c
+++ b/nptl/pthread_rwlock_rdlock.c
@@ -23,6 +23,7 @@
#include <pthreadP.h>
#include <stap-probe.h>
#include <elide.h>
+#include <stdbool.h>
/* Acquire read lock for RWLOCK. Slow path. */
@@ -30,6 +31,7 @@ static int __attribute__((noinline))
__pthread_rwlock_rdlock_slow (pthread_rwlock_t *rwlock)
{
int result = 0;
+ bool wake = false;
/* Lock is taken in caller. */
@@ -81,7 +83,17 @@ __pthread_rwlock_rdlock_slow (pthread_rwlock_t *rwlock)
result = EAGAIN;
}
else
- LIBC_PROBE (rdlock_acquire_read, 1, rwlock);
+ {
+ LIBC_PROBE (rdlock_acquire_read, 1, rwlock);
+ /* See pthread_rwlock_rdlock. */
+ if (rwlock->__data.__nr_readers == 1
+ && rwlock->__data.__nr_readers_queued > 0
+ && rwlock->__data.__nr_writers_queued > 0)
+ {
+ ++rwlock->__data.__readers_wakeup;
+ wake = true;
+ }
+ }
break;
}
@@ -90,6 +102,10 @@ __pthread_rwlock_rdlock_slow (pthread_rwlock_t *rwlock)
/* We are done, free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
+ if (wake)
+ lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
+ rwlock->__data.__shared);
+
return result;
}
@@ -100,6 +116,7 @@ int
__pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
{
int result = 0;
+ bool wake = false;
LIBC_PROBE (rdlock_entry, 1, rwlock);
@@ -126,11 +143,30 @@ __pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
result = EAGAIN;
}
else
- LIBC_PROBE (rdlock_acquire_read, 1, rwlock);
+ {
+ LIBC_PROBE (rdlock_acquire_read, 1, rwlock);
+ /* If we are the first reader, and there are blocked readers and
+ writers (which we don't prefer, see above), then it can be the
+ case that we stole the lock from a writer that was already woken
+ to acquire it. That means that we need to take over the writer's
+ responsibility to wake all readers (see pthread_rwlock_unlock).
+ Thus, wake all readers in this case. */
+ if (rwlock->__data.__nr_readers == 1
+ && rwlock->__data.__nr_readers_queued > 0
+ && rwlock->__data.__nr_writers_queued > 0)
+ {
+ ++rwlock->__data.__readers_wakeup;
+ wake = true;
+ }
+ }
/* We are done, free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
+ if (wake)
+ lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
+ rwlock->__data.__shared);
+
return result;
}
diff --git a/nptl/pthread_rwlock_timedrdlock.c b/nptl/pthread_rwlock_timedrdlock.c
index 0212b49..63fb313 100644
--- a/nptl/pthread_rwlock_timedrdlock.c
+++ b/nptl/pthread_rwlock_timedrdlock.c
@@ -23,6 +23,7 @@
#include <pthreadP.h>
#include <sys/time.h>
#include <kernel-features.h>
+#include <stdbool.h>
/* Try to acquire read lock for RWLOCK or return after specfied time. */
@@ -32,6 +33,7 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
const struct timespec *abstime;
{
int result = 0;
+ bool wake = false;
/* Make sure we are alone. */
lll_lock(rwlock->__data.__lock, rwlock->__data.__shared);
@@ -53,6 +55,17 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
--rwlock->__data.__nr_readers;
result = EAGAIN;
}
+ else
+ {
+ /* See pthread_rwlock_rdlock. */
+ if (rwlock->__data.__nr_readers == 1
+ && rwlock->__data.__nr_readers_queued > 0
+ && rwlock->__data.__nr_writers_queued > 0)
+ {
+ ++rwlock->__data.__readers_wakeup;
+ wake = true;
+ }
+ }
break;
}
@@ -153,5 +166,9 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
/* We are done, free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
+ if (wake)
+ lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
+ rwlock->__data.__shared);
+
return result;
}
diff --git a/nptl/pthread_rwlock_timedwrlock.c b/nptl/pthread_rwlock_timedwrlock.c
index a759fa9..c542534 100644
--- a/nptl/pthread_rwlock_timedwrlock.c
+++ b/nptl/pthread_rwlock_timedwrlock.c
@@ -141,8 +141,16 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
/* If we prefer writers, it can have happened that readers blocked
for us to acquire the lock first. If we have timed out, we need
to wake such readers if there are any, and if there is no writer
- currently (otherwise, the writer will take care of wake-up). */
- if (!PTHREAD_RWLOCK_PREFER_READER_P (rwlock)
+ currently (otherwise, the writer will take care of wake-up).
+ Likewise, even if we prefer readers, we can be responsible for
+ wake-up (see pthread_rwlock_unlock) if no reader or writer has
+ acquired the lock. We have timed out and thus not consumed a
+ futex wake-up; therefore, if there is no other blocked writer
+ that would consume the wake-up and thus take over responsibility,
+ we need to wake blocked readers. */
+ if ((!PTHREAD_RWLOCK_PREFER_READER_P (rwlock)
+ || ((rwlock->__data.__nr_readers == 0)
+ && (rwlock->__data.__nr_writers_queued == 0)))
&& (rwlock->__data.__nr_readers_queued > 0)
&& (rwlock->__data.__writer == 0))
{
diff --git a/nptl/pthread_rwlock_tryrdlock.c b/nptl/pthread_rwlock_tryrdlock.c
index d51d9aa..cde123f 100644
--- a/nptl/pthread_rwlock_tryrdlock.c
+++ b/nptl/pthread_rwlock_tryrdlock.c
@@ -20,12 +20,14 @@
#include "pthreadP.h"
#include <lowlevellock.h>
#include <elide.h>
+#include <stdbool.h>
int
__pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
{
int result = EBUSY;
+ bool wake = false;
if (ELIDE_TRYLOCK (rwlock->__data.__rwelision,
rwlock->__data.__lock == 0
@@ -45,11 +47,25 @@ __pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
result = EAGAIN;
}
else
- result = 0;
+ {
+ result = 0;
+ /* See pthread_rwlock_rdlock. */
+ if (rwlock->__data.__nr_readers == 1
+ && rwlock->__data.__nr_readers_queued > 0
+ && rwlock->__data.__nr_writers_queued > 0)
+ {
+ ++rwlock->__data.__readers_wakeup;
+ wake = true;
+ }
+ }
}
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
+ if (wake)
+ lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
+ rwlock->__data.__shared);
+
return result;
}
strong_alias (__pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock)
diff --git a/nptl/pthread_rwlock_unlock.c b/nptl/pthread_rwlock_unlock.c
index b8336f6..d2ad4b0 100644
--- a/nptl/pthread_rwlock_unlock.c
+++ b/nptl/pthread_rwlock_unlock.c
@@ -40,8 +40,13 @@ __pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
rwlock->__data.__writer = 0;
else
--rwlock->__data.__nr_readers;
+ /* If there are still readers present, we do not yet need to wake writers
+ nor are responsible to wake any readers. */
if (rwlock->__data.__nr_readers == 0)
{
+ /* Note that if there is a blocked writer, we effectively make it
+ responsible for waking any readers because we don't wake readers in
+ this case. */
if (rwlock->__data.__nr_writers_queued)
{
++rwlock->__data.__writer_wakeup;
diff --git a/nptl/tst-rwlock16.c b/nptl/tst-rwlock16.c
new file mode 100644
index 0000000..8e661db
--- /dev/null
+++ b/nptl/tst-rwlock16.c
@@ -0,0 +1,183 @@
+/* Copyright (C) 2015 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This tests that with a reader-preferring rwlock, all readers are woken if
+ one reader "steals" lock ownership from a blocked writer. */
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <semaphore.h>
+#include <unistd.h>
+
+/* If we strictly prefer writers over readers, a program must not expect
+ that, in the presence of concurrent writers, one reader will also acquire
+ the lock when another reader has already done so. Thus, use the
+ default rwlock type that does not strictly prefer writers. */
+static pthread_rwlock_t r = PTHREAD_RWLOCK_INITIALIZER;
+
+static pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t cv = PTHREAD_COND_INITIALIZER;
+
+/* Avoid using glibc-internal atomic operations. */
+static sem_t stop;
+static int consumer_stop = 0;
+
+static void *
+writer (void *arg)
+{
+ int s;
+
+ do
+ {
+ if (pthread_rwlock_wrlock (&r) != 0)
+ {
+ puts ("wrlock failed");
+ exit (EXIT_FAILURE);
+ }
+ if (pthread_rwlock_unlock (&r) != 0)
+ {
+ puts ("unlock failed");
+ exit (EXIT_FAILURE);
+ }
+ sem_getvalue (&stop, &s);
+ }
+ while (s == 0);
+ return NULL;
+}
+
+static void *
+reader_producer (void *arg)
+{
+ int s;
+
+ do
+ {
+ if (pthread_rwlock_rdlock (&r) != 0)
+ {
+ puts ("rdlock reader failed");
+ exit (EXIT_FAILURE);
+ }
+
+ sem_getvalue (&stop, &s);
+
+ pthread_mutex_lock (&m);
+ if (s != 0)
+ consumer_stop = 1;
+ pthread_cond_signal (&cv);
+ pthread_mutex_unlock (&m);
+
+ if (pthread_rwlock_unlock (&r) != 0)
+ {
+ puts ("unlock reader failed");
+ exit (EXIT_FAILURE);
+ }
+ }
+ while (s == 0);
+ puts ("producer finished");
+ return NULL;
+}
+
+static void *
+reader_consumer (void *arg)
+{
+ int s;
+
+ do
+ {
+ if (pthread_rwlock_rdlock (&r) != 0)
+ {
+ puts ("rdlock reader failed");
+ exit (EXIT_FAILURE);
+ }
+
+ pthread_mutex_lock (&m);
+ s = consumer_stop;
+ if (s == 0)
+ pthread_cond_wait (&cv, &m);
+ pthread_mutex_unlock (&m);
+
+ if (pthread_rwlock_unlock (&r) != 0)
+ {
+ puts ("unlock reader failed");
+ exit (EXIT_FAILURE);
+ }
+ }
+ while (s == 0);
+ puts ("consumer finished");
+ return NULL;
+}
+
+
+static int
+do_test (void)
+{
+ pthread_t w1, w2, rp, rc;
+
+ if (pthread_create (&w1, NULL, writer, NULL) != 0)
+ {
+ puts ("create failed");
+ return 1;
+ }
+ if (pthread_create (&w2, NULL, writer, NULL) != 0)
+ {
+ puts ("create failed");
+ return 1;
+ }
+ if (pthread_create (&rc, NULL, reader_consumer, NULL) != 0)
+ {
+ puts ("create failed");
+ return 1;
+ }
+ if (pthread_create (&rp, NULL, reader_producer, NULL) != 0)
+ {
+ puts ("create failed");
+ return 1;
+ }
+
+ sleep (2);
+ sem_post (&stop);
+
+ if (pthread_join (w1, NULL) != 0)
+ {
+ puts ("w1 join failed");
+ return 1;
+ }
+ if (pthread_join (w2, NULL) != 0)
+ {
+ puts ("w2 join failed");
+ return 1;
+ }
+ if (pthread_join (rp, NULL) != 0)
+ {
+ puts ("reader_producer join failed");
+ return 1;
+ }
+ if (pthread_join (rc, NULL) != 0)
+ {
+ puts ("reader_consumer join failed");
+ return 1;
+ }
+
+ return 0;
+}
+
+
+#define TIMEOUT 3
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=3c9c61febede148b79d8509e16588152d99b3774
commit 3c9c61febede148b79d8509e16588152d99b3774
Author: Torvald Riegel <triegel@redhat.com>
Date: Tue Apr 21 20:34:21 2015 +0200
Fix lost wake-up when pthread_rwlock_timedrwlock times out.
If we set up a rwlock to prefer writers (and disallow recursive rdlock
acquisitions), then readers will block for writers that are blocked to
acquire the lock (otherwise, readers could constantly enter and exit,
and the writer would never get the lock). However, the existing
implementation did not wake such readers when the writer timed out.
This patch adds the missing wake-up.
There's no similar case for writers being blocked on readers.
diff --git a/ChangeLog b/ChangeLog
index e0e6d6b..423ccea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-06-04 Torvald Riegel <triegel@redhat.com>
+
+ [BZ #18324]
+ * nptl/pthread_rwlock_timedwrlock.c (pthread_rwlock_timedwrlock): Add
+ missing wake-up of readers.
+ * nptl/tst-rwlock15.c: New file.
+ * nptl/Makefile (tests): Add new test.
+
2015-06-03 Roland McGrath <roland@hack.frob.com>
* sysdeps/nacl/nacl-interfaces.c (try_supply): New static function.
diff --git a/NEWS b/NEWS
index 43c2cc7..f8ad875 100644
--- a/NEWS
+++ b/NEWS
@@ -18,8 +18,9 @@ Version 2.22
18020, 18029, 18030, 18032, 18036, 18038, 18039, 18042, 18043, 18046,
18047, 18049, 18068, 18080, 18093, 18100, 18104, 18110, 18111, 18116,
18125, 18128, 18138, 18185, 18196, 18197, 18206, 18210, 18211, 18217,
- 18220, 18221, 18234, 18244, 18247, 18287, 18319, 18333, 18346, 18397,
- 18409, 18410, 18412, 18418, 18422, 18434, 18444, 18468, 18469, 18470.
+ 18220, 18221, 18234, 18244, 18247, 18287, 18319, 18324, 18333, 18346,
+ 18397, 18409, 18410, 18412, 18418, 18422, 18434, 18444, 18468, 18469,
+ 18470.
* Cache information can be queried via sysconf() function on s390 e.g. with
_SC_LEVEL1_ICACHE_SIZE as argument.
diff --git a/nptl/Makefile b/nptl/Makefile
index 3dd2944..62436ac 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -231,6 +231,7 @@ tests = tst-typesizes \
tst-rwlock1 tst-rwlock2 tst-rwlock2a tst-rwlock3 tst-rwlock4 \
tst-rwlock5 tst-rwlock6 tst-rwlock7 tst-rwlock8 tst-rwlock9 \
tst-rwlock10 tst-rwlock11 tst-rwlock12 tst-rwlock13 tst-rwlock14 \
+ tst-rwlock15 \
tst-once1 tst-once2 tst-once3 tst-once4 \
tst-key1 tst-key2 tst-key3 tst-key4 \
tst-sem1 tst-sem2 tst-sem3 tst-sem4 tst-sem5 tst-sem6 tst-sem7 \
diff --git a/nptl/pthread_rwlock_timedwrlock.c b/nptl/pthread_rwlock_timedwrlock.c
index 416f6e2..a759fa9 100644
--- a/nptl/pthread_rwlock_timedwrlock.c
+++ b/nptl/pthread_rwlock_timedwrlock.c
@@ -23,6 +23,7 @@
#include <pthreadP.h>
#include <sys/time.h>
#include <kernel-features.h>
+#include <stdbool.h>
/* Try to acquire write lock for RWLOCK or return after specfied time. */
@@ -32,6 +33,7 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
const struct timespec *abstime;
{
int result = 0;
+ bool wake_readers = false;
/* Make sure we are alone. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
@@ -136,6 +138,17 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
if (err == -ETIMEDOUT)
{
result = ETIMEDOUT;
+ /* If we prefer writers, it can have happened that readers blocked
+ for us to acquire the lock first. If we have timed out, we need
+ to wake such readers if there are any, and if there is no writer
+ currently (otherwise, the writer will take care of wake-up). */
+ if (!PTHREAD_RWLOCK_PREFER_READER_P (rwlock)
+ && (rwlock->__data.__nr_readers_queued > 0)
+ && (rwlock->__data.__writer == 0))
+ {
+ ++rwlock->__data.__readers_wakeup;
+ wake_readers = true;
+ }
break;
}
}
@@ -143,5 +156,10 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
/* We are done, free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
+ /* Might be required after timeouts. */
+ if (wake_readers)
+ lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
+ rwlock->__data.__shared);
+
return result;
}
diff --git a/nptl/tst-rwlock15.c b/nptl/tst-rwlock15.c
new file mode 100644
index 0000000..b292701
--- /dev/null
+++ b/nptl/tst-rwlock15.c
@@ -0,0 +1,116 @@
+/* Copyright (C) 2015 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This tests that a writer that is preferred -- but times out due to a
+ reader being present -- does not miss to wake other readers blocked on the
+ writer's pending lock acquisition. */
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+/* The bug existed in the code that strictly prefers writers over readers. */
+static pthread_rwlock_t r = PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP;
+
+static void *
+writer (void *arg)
+{
+ struct timespec ts;
+ if (clock_gettime (CLOCK_REALTIME, &ts) != 0)
+ {
+ puts ("clock_gettime failed");
+ exit (EXIT_FAILURE);
+ }
+ ts.tv_sec += 1;
+ int e = pthread_rwlock_timedwrlock (&r, &ts);
+ if (e != ETIMEDOUT)
+ {
+ puts ("timedwrlock did not time out");
+ exit (EXIT_FAILURE);
+ }
+ return NULL;
+}
+
+static void *
+reader (void *arg)
+{
+ /* This isn't a reliable way to get the interleaving we need (because a
+ failed trylock doesn't synchronize with the writer, and because we could
+ try to lock after the writer has already timed out). However, both will
+ just lead to false positives. */
+ int e;
+ while ((e = pthread_rwlock_tryrdlock (&r)) != EBUSY)
+ {
+ if (e != 0)
+ exit (EXIT_FAILURE);
+ pthread_rwlock_unlock (&r);
+ }
+ e = pthread_rwlock_rdlock (&r);
+ if (e != 0)
+ {
+ puts ("reader rdlock failed");
+ exit (EXIT_FAILURE);
+ }
+ pthread_rwlock_unlock (&r);
+ return NULL;
+}
+
+
+static int
+do_test (void)
+{
+ /* Grab a rdlock, then create a writer and a reader, and wait until they
+ finished. */
+
+ if (pthread_rwlock_rdlock (&r) != 0)
+ {
+ puts ("initial rdlock failed");
+ return 1;
+ }
+
+ pthread_t thw;
+ if (pthread_create (&thw, NULL, writer, NULL) != 0)
+ {
+ puts ("create failed");
+ return 1;
+ }
+ pthread_t thr;
+ if (pthread_create (&thr, NULL, reader, NULL) != 0)
+ {
+ puts ("create failed");
+ return 1;
+ }
+
+ if (pthread_join (thw, NULL) != 0)
+ {
+ puts ("writer join failed");
+ return 1;
+ }
+ if (pthread_join (thr, NULL) != 0)
+ {
+ puts ("reader join failed");
+ return 1;
+ }
+
+ return 0;
+}
+
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 22 +++++
NEWS | 23 +++--
nptl/Makefile | 1 +
nptl/pthread_rwlock_rdlock.c | 40 ++++++++-
nptl/pthread_rwlock_timedrdlock.c | 17 ++++
nptl/pthread_rwlock_timedwrlock.c | 26 +++++
nptl/pthread_rwlock_tryrdlock.c | 18 ++++-
nptl/pthread_rwlock_unlock.c | 5 +
nptl/tst-rwlock15.c | 116 +++++++++++++++++++++++
nptl/tst-rwlock16.c | 183 +++++++++++++++++++++++++++++++++++++
10 files changed, 437 insertions(+), 14 deletions(-)
create mode 100644 nptl/tst-rwlock15.c
create mode 100644 nptl/tst-rwlock16.c
hooks/post-receive
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