[lttng-dev] [PATCH lttng-ust] Bugfix for #745 deadlock with baddr statedump+fork
Paul Woegerer
paul_woegerer at mentor.com
Fri Jul 4 08:21:52 EDT 2014
Signed-off-by: Paul Woegerer <paul_woegerer at mentor.com>
---
liblttng-ust/lttng-ust-comm.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 5df33f5..8fa2e03 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -173,6 +173,7 @@ void ust_unlock(void)
* daemon problems).
*/
static sem_t constructor_wait;
+static sem_t fork_child_wait;
/*
* Doing this for both the global and local sessiond.
*/
@@ -502,11 +503,18 @@ int handle_register_done(struct sock_info *sock_info)
static
void handle_pending_statedump(struct sock_info *sock_info)
{
+ int ret;
int ctor_passed = sock_info->constructor_sem_posted;
if (ctor_passed && sock_info->statedump_pending) {
+ do {
+ ret = sem_wait(&fork_child_wait);
+ } while (ret < 0 && errno == EINTR);
+ assert(!ret);
sock_info->statedump_pending = 0;
lttng_handle_pending_statedump(sock_info);
+ ret = sem_post(&fork_child_wait);
+ assert(!ret);
}
}
@@ -1436,6 +1444,9 @@ void __attribute__((constructor)) lttng_ust_init(void)
ret = sem_init(&constructor_wait, 0, 0);
assert(!ret);
+ ret = sem_init(&fork_child_wait, 0, 1);
+ assert(!ret);
+
ret = setup_local_apps();
if (ret) {
DBG("local apps setup returned %d", ret);
@@ -1627,6 +1638,12 @@ void ust_before_fork(sigset_t *save_sigset)
if (ret == -1) {
PERROR("sigprocmask");
}
+
+ do {
+ ret = sem_wait(&fork_child_wait);
+ } while (ret < 0 && errno == EINTR);
+ assert(!ret);
+
ust_lock_nocheck();
rcu_bp_before_fork();
}
@@ -1637,6 +1654,10 @@ static void ust_after_fork_common(sigset_t *restore_sigset)
DBG("process %d", getpid());
ust_unlock();
+
+ ret = sem_post(&fork_child_wait);
+ assert(!ret);
+
/* Restore signals */
ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
if (ret == -1) {
--
2.0.1
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