Fix: consumer relay sender RCU usage

[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.c

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 00bb7f7212cac7f0ccf4f4a6c91ef80dbb4b58ef..551d8579a21ad4c6e86bed6904df6290c4304d24 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -59,6 +59,9 @@ ssize_t lttng_kconsumer_on_read_subbuffer_mmap(
        uint64_t metadata_id;
        struct consumer_relayd_sock_pair *relayd = NULL;
 
+       /* RCU lock for the relayd pointer */
+       rcu_read_lock();
+
        /* Flag that the current stream if set for network streaming. */
        if (stream->net_seq_idx != -1) {
                relayd = consumer_find_relayd(stream->net_seq_idx);
@@ -76,9 +79,6 @@ ssize_t lttng_kconsumer_on_read_subbuffer_mmap(
                goto end;
        }
 
-       /* RCU lock for the relayd pointer */
-       rcu_read_lock();
-
        /* Handle stream on the relayd if the output is on the network */
        if (relayd) {
                /*
@@ -178,6 +178,9 @@ ssize_t lttng_kconsumer_on_read_subbuffer_splice(
        uint64_t metadata_id;
        struct consumer_relayd_sock_pair *relayd = NULL;
 
+       /* RCU lock for the relayd pointer */
+       rcu_read_lock();
+
        /* Flag that the current stream if set for network streaming. */
        if (stream->net_seq_idx != -1) {
                relayd = consumer_find_relayd(stream->net_seq_idx);
@@ -186,9 +189,6 @@ ssize_t lttng_kconsumer_on_read_subbuffer_splice(
                }
        }
 
-       /* RCU lock for the relayd pointer */
-       rcu_read_lock();
-
        /* Write metadata stream id before payload */
        if (stream->metadata_flag && relayd) {
                /*
@@ -374,6 +374,9 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                return -ENOENT;
        }
 
+       /* relayd needs RCU read-side protection */
+       rcu_read_lock();
+
        switch (msg.cmd_type) {
        case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
        {
@@ -580,6 +583,7 @@ end:
                ret = write(ctx->consumer_poll_pipe[1], "", 1);
        } while (ret < 0 && errno == EINTR);
 end_nosignal:
+       rcu_read_unlock();
        return 0;
 }