The ioctl syscall is not a pthread cancellation point. So, when
device-mapper is waiting on events, pthread_cancel won't cancel
the waiter thread. This patch makes the waiter threads handle
SIGUSR2, and has stop_waiter_thread() signal it to break out of
waiting on dm events. Unfortunately, there is still a possibility
of the signal arriving before the ioctl, and the waiter thread
still hanging until the devices are reloaded.
Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
libmultipath/waiter.c | 9 +++++++++
multipathd/main.c | 8 ++++++++
2 files changed, 17 insertions(+)
diff --git a/libmultipath/waiter.c b/libmultipath/waiter.c
index 5094290..7cedd4b 100644
--- a/libmultipath/waiter.c
+++ b/libmultipath/waiter.c
@@ -57,6 +57,7 @@ void stop_waiter_thread (struct multipath *mpp, struct vectors *vecs)
thread = mpp->waiter;
mpp->waiter = (pthread_t)0;
pthread_cancel(thread);
+ pthread_kill(thread, SIGUSR2);
}
/*
@@ -65,6 +66,7 @@ void stop_waiter_thread (struct multipath *mpp, struct vectors *vecs)
*/
int waiteventloop (struct event_thread *waiter)
{
+ sigset_t set, oldset;
int event_nr;
int r;
@@ -97,8 +99,15 @@ int waiteventloop (struct event_thread *waiter)
dm_task_no_open_count(waiter->dmt);
/* wait */
+ sigemptyset(&set);
+ sigaddset(&set, SIGUSR2);
+ pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
+
+ pthread_testcancel();
r = dm_task_run(waiter->dmt);
+ pthread_testcancel();
+ pthread_sigmask(SIG_SETMASK, &oldset, NULL);
dm_task_destroy(waiter->dmt);
waiter->dmt = NULL;
diff --git a/multipathd/main.c b/multipathd/main.c
index 7c0e313..c388e42 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -1521,6 +1521,12 @@ sigusr1 (int sig)
}
static void
+sigusr2 (int sig)
+{
+ condlog(3, "SIGUSR2 received");
+}
+
+static void
signal_init(void)
{
sigset_t set;
@@ -1528,10 +1534,12 @@ signal_init(void)
sigemptyset(&set);
sigaddset(&set, SIGHUP);
sigaddset(&set, SIGUSR1);
+ sigaddset(&set, SIGUSR2);
pthread_sigmask(SIG_BLOCK, &set, NULL);
signal_set(SIGHUP, sighup);
signal_set(SIGUSR1, sigusr1);
+ signal_set(SIGUSR2, sigusr2);
signal_set(SIGINT, sigend);
signal_set(SIGTERM, sigend);
signal(SIGPIPE, SIG_IGN);
--
1.8.4.2
--
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