Signed-off-by: Paul Woegerer <[email protected]>
---
liblttng-ust/lttng-ust-comm.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 5df33f5..a73808e 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -86,6 +86,14 @@ static DEFINE_URCU_TLS(int, ust_mutex_nest);
*/
static pthread_mutex_t ust_exit_mutex = PTHREAD_MUTEX_INITIALIZER;
+/*
+ * ust_fork_mutex protects base address statedump tracing against forks. It
+ * prevents the dynamic loader lock to be taken (by base address statedump
+ * tracing) while a fork is happening, thus preventing deadlock issues with
+ * the dynamic loader lock.
+ */
+static pthread_mutex_t ust_fork_mutex = PTHREAD_MUTEX_INITIALIZER;
+
/* Should the ust comm thread quit ? */
static int lttng_ust_comm_should_quit;
@@ -505,8 +513,10 @@ void handle_pending_statedump(struct sock_info *sock_info)
int ctor_passed = sock_info->constructor_sem_posted;
if (ctor_passed && sock_info->statedump_pending) {
+ pthread_mutex_lock(&ust_fork_mutex);
sock_info->statedump_pending = 0;
lttng_handle_pending_statedump(sock_info);
+ pthread_mutex_unlock(&ust_fork_mutex);
}
}
@@ -1627,6 +1637,9 @@ void ust_before_fork(sigset_t *save_sigset)
if (ret == -1) {
PERROR("sigprocmask");
}
+
+ pthread_mutex_lock(&ust_fork_mutex);
+
ust_lock_nocheck();
rcu_bp_before_fork();
}
@@ -1637,6 +1650,9 @@ static void ust_after_fork_common(sigset_t
*restore_sigset)
DBG("process %d", getpid());
ust_unlock();
+
+ pthread_mutex_unlock(&ust_fork_mutex);
+
/* Restore signals */
ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
if (ret == -1) {
--
2.0.1
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