From: mwilck@suse.com
To: Christophe Varoqui <christophe.varoqui@opensvc.com>,
Benjamin Marzinski <bmarzins@redhat.com>
Cc: lixiaokeng@huawei.com, dm-devel@redhat.com,
Martin Wilck <mwilck@suse.com>
Subject: [PATCH 18/23] libmultipath: fix log_thread startup and teardown
Date: Thu, 24 Sep 2020 15:40:49 +0200 [thread overview]
Message-ID: <20200924134054.14632-19-mwilck@suse.com> (raw)
In-Reply-To: <20200924134054.14632-1-mwilck@suse.com>
From: Martin Wilck <mwilck@suse.com>
This fixes several issues with the log_thread. First, the running
flag logq_running should be set by the thread itself, not by
log_thread_start()/_stop(). Second, the thread was both cancelled and
terminated via a flag (again, logq_running). It's sufficient,
and better, to just cancel it and use logq_running as indication for
successful termination. Third, the locking wasn't cancel-safe in some
places. Forth, log_thread_start() and log_thread_stop() didn't wait for
startup/teardown properly. Fifth, using (pthread_t)0 is wrong (pthread_t is
opaque; there's no guarantee that 0 is not a valid pthread_t value). Finally,
pthread_cancel() was called under logq_lock, which doesn't make sense to
me at all.
Signed-off-by: Martin Wilck <mwilck@suse.com>
---
libmultipath/log_pthread.c | 59 ++++++++++++++++++++++++++++----------
1 file changed, 44 insertions(+), 15 deletions(-)
diff --git a/libmultipath/log_pthread.c b/libmultipath/log_pthread.c
index 0c327ff..5825e66 100644
--- a/libmultipath/log_pthread.c
+++ b/libmultipath/log_pthread.c
@@ -13,6 +13,7 @@
#include "log_pthread.h"
#include "log.h"
#include "lock.h"
+#include "util.h"
static pthread_t log_thr;
@@ -56,28 +57,45 @@ static void flush_logqueue (void)
} while (empty == 0);
}
+static void cleanup_log_thread(__attribute((unused)) void *arg)
+{
+ logdbg(stderr, "log thread exiting");
+ pthread_mutex_lock(&logev_lock);
+ logq_running = 0;
+ pthread_cond_signal(&logev_cond);
+ pthread_mutex_unlock(&logev_lock);
+}
+
static void * log_thread (__attribute__((unused)) void * et)
{
int running;
pthread_mutex_lock(&logev_lock);
- logq_running = 1;
+ running = logq_running;
+ if (!running)
+ logq_running = 1;
+ pthread_cond_signal(&logev_cond);
pthread_mutex_unlock(&logev_lock);
+ if (running)
+ /* already started */
+ return NULL;
+ pthread_cleanup_push(cleanup_log_thread, NULL);
mlockall(MCL_CURRENT | MCL_FUTURE);
logdbg(stderr,"enter log_thread\n");
while (1) {
pthread_mutex_lock(&logev_lock);
- if (logq_running && !log_messages_pending)
+ pthread_cleanup_push(cleanup_mutex, &logev_lock);
+ while (!log_messages_pending)
+ /* this is a cancellation point */
pthread_cond_wait(&logev_cond, &logev_lock);
log_messages_pending = 0;
- running = logq_running;
- pthread_mutex_unlock(&logev_lock);
- if (!running)
- break;
+ pthread_cleanup_pop(1);
+
flush_logqueue();
}
+ pthread_cleanup_pop(1);
return NULL;
}
@@ -98,6 +116,12 @@ void log_thread_start (pthread_attr_t *attr)
exit(1);
}
+ pthread_mutex_lock(&logev_lock);
+ pthread_cleanup_push(cleanup_mutex, &logev_lock);
+ /* wait for thread startup */
+ while (!logq_running)
+ pthread_cond_wait(&logev_cond, &logev_lock);
+ pthread_cleanup_pop(1);
return;
}
@@ -112,21 +136,26 @@ void log_thread_reset (void)
void log_thread_stop (void)
{
+ int running;
+
if (!la)
return;
-
logdbg(stderr,"enter log_thread_stop\n");
pthread_mutex_lock(&logev_lock);
- logq_running = 0;
- pthread_cond_signal(&logev_cond);
- pthread_mutex_unlock(&logev_lock);
+ pthread_cleanup_push(cleanup_mutex, &logev_lock);
+ running = logq_running;
+ if (running) {
+ pthread_cancel(log_thr);
+ pthread_cond_signal(&logev_cond);
+ }
+ while (logq_running)
+ pthread_cond_wait(&logev_cond, &logev_lock);
+ pthread_cleanup_pop(1);
+
+ if (running)
+ pthread_join(log_thr, NULL);
- pthread_mutex_lock(&logq_lock);
- pthread_cancel(log_thr);
- pthread_mutex_unlock(&logq_lock);
- pthread_join(log_thr, NULL);
- log_thr = (pthread_t)0;
flush_logqueue();
--
2.28.0
next prev parent reply other threads:[~2020-09-24 13:40 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 13:40 [PATCH 00/23] libmultipath: improve cleanup on exit mwilck
2020-09-24 13:40 ` [PATCH 01/23] multipathd: uxlsnr: avoid deadlock " mwilck
2020-09-26 1:52 ` Benjamin Marzinski
2020-09-26 13:00 ` Martin Wilck
2020-09-24 13:40 ` [PATCH 02/23] multipathd: Fix liburcu memory leak mwilck
2020-09-24 13:40 ` [PATCH 03/23] multipathd: move handling of io_err_stat_attr into libmultipath mwilck
2020-09-24 13:40 ` [PATCH 04/23] multipathd: move vecs desctruction into cleanup function mwilck
2020-09-24 13:40 ` [PATCH 05/23] multipathd: make some globals static mwilck
2020-09-24 13:40 ` [PATCH 06/23] multipathd: move threads destruction into separate function mwilck
2020-09-24 13:40 ` [PATCH 07/23] multipathd: move conf " mwilck
2020-09-28 18:03 ` Benjamin Marzinski
2020-09-29 9:12 ` Martin Wilck
2020-09-24 13:40 ` [PATCH 08/23] multipathd: move pid " mwilck
2020-09-24 13:40 ` [PATCH 09/23] multipathd: close pidfile on exit mwilck
2020-09-24 13:40 ` [PATCH 10/23] multipathd: add helper for systemd notification at exit mwilck
2020-09-24 13:40 ` [PATCH 11/23] multipathd: child(): call cleanups in failure case, too mwilck
2020-09-24 13:40 ` [PATCH 12/23] multipathd: unwatch_all_dmevents: check if waiter is initialized mwilck
2020-09-24 13:40 ` [PATCH 13/23] multipathd: print error message if config can't be loaded mwilck
2020-09-24 13:40 ` [PATCH 14/23] libmultipath: add libmp_dm_exit() mwilck
2020-09-28 18:41 ` Benjamin Marzinski
2020-09-24 13:40 ` [PATCH 15/23] multipathd: fixup libdm deinitialization mwilck
2020-09-24 13:40 ` [PATCH 16/23] libmultipath: log_thread_stop(): check if logarea is initialized mwilck
2020-09-24 13:40 ` [PATCH 17/23] multipathd: add cleanup_child() exit handler mwilck
2020-09-24 13:40 ` mwilck [this message]
2020-09-28 20:15 ` [PATCH 18/23] libmultipath: fix log_thread startup and teardown Benjamin Marzinski
2020-09-29 9:18 ` Martin Wilck
2020-09-24 13:40 ` [PATCH 19/23] multipathd: move cleanup_{prio, checkers, foreign} to libmultipath_exit mwilck
2020-09-28 20:26 ` Benjamin Marzinski
2020-09-29 9:31 ` Martin Wilck
2020-09-29 17:50 ` Benjamin Marzinski
2020-09-24 13:40 ` [PATCH 20/23] multipath: use atexit() for cleanup handlers mwilck
2020-09-24 13:40 ` [PATCH 21/23] mpathpersist: " mwilck
2020-09-24 13:40 ` [PATCH 22/23] multipath: fix leaks in check_path_valid() mwilck
2020-09-24 13:40 ` [PATCH 23/23] multipath-tools: mpath-tools.supp: file with valgrind suppressions mwilck
2020-09-24 20:58 ` Benjamin Marzinski
2020-09-25 9:53 ` Martin Wilck
2020-09-28 20:51 ` [PATCH 00/23] libmultipath: improve cleanup on exit Benjamin Marzinski
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