Fix: duplicated kernel consumer socket locking

Commit 9d1103e introduced a bug causing a deadlock on snapshot record.
Function consumer_snapshot_channel is called with the lock held causing
the pthread_mutex_lock call inside to hang forever.

Because consumer_snapshot_channel now acquires the lock before using the
socket. No need to acquire the lock before calling the function.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index d76166a6e9387c965acf66c347959553686bacfc..b1a3f0b70c8cf9b0868113652c3cbcb23ca4e78a 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -1028,12 +1028,10 @@ int kernel_snapshot_record(struct ltt_kernel_session *ksess,
 
                /* For each channel, ask the consumer to snapshot it. */
                cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
-                       pthread_mutex_lock(socket->lock);
                        ret = consumer_snapshot_channel(socket, chan->fd, output, 0,
                                        ksess->uid, ksess->gid,
                                        DEFAULT_KERNEL_TRACE_DIR, wait,
                                        nb_packets_per_stream);
-                       pthread_mutex_unlock(socket->lock);
                        if (ret < 0) {
                                ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
                                (void) kernel_consumer_destroy_metadata(socket,
@@ -1043,11 +1041,9 @@ int kernel_snapshot_record(struct ltt_kernel_session *ksess,
                }
 
                /* Snapshot metadata, */
-               pthread_mutex_lock(socket->lock);
                ret = consumer_snapshot_channel(socket, ksess->metadata->fd, output,
                                1, ksess->uid, ksess->gid,
                                DEFAULT_KERNEL_TRACE_DIR, wait, 0);
-               pthread_mutex_unlock(socket->lock);
                if (ret < 0) {
                        ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
                        goto error_consumer;