From 58f3ca76ddd0d871fc1b71d816bdbabe1d7adeb1 Mon Sep 17 00:00:00 2001 From: David Goulet Date: Thu, 12 Jan 2012 13:04:51 -0500 Subject: [PATCH 1/1] Fix out of order channel insert in hash table The channel, ust-app side, was added to the hash table of the session even if the creation failed on the tracer side. When enabling event for that channel, a segfault was hit since the channel did not exist on the tracer side and channel_data was NULL at this point. Now the channel insertion in the hash table is done *after* enabling it on the tracer side. Reported-by: Mathieu Desnoyers Signed-off-by: David Goulet --- lttng-sessiond/channel.c | 9 ++++++--- lttng-sessiond/ust-app.c | 6 +++--- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/lttng-sessiond/channel.c b/lttng-sessiond/channel.c index b4dc48d16..3dc04ccb8 100644 --- a/lttng-sessiond/channel.c +++ b/lttng-sessiond/channel.c @@ -236,11 +236,16 @@ int channel_ust_create(struct ltt_ust_session *usess, int domain, ret = LTTCOMM_FATAL; goto error; } + uchan->enabled = 1; switch (domain) { case LTTNG_DOMAIN_UST: DBG2("Channel %s being created in UST global domain", uchan->name); - chan_ht = usess->domain_global.channels; + + /* Adding the channel to the channel hash table. */ + rcu_read_lock(); + lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node); + rcu_read_unlock(); /* Enable channel for global domain */ ret = ust_app_create_channel_glb(usess, uchan); @@ -258,8 +263,6 @@ int channel_ust_create(struct ltt_ust_session *usess, int domain, goto error_free_chan; } - uchan->enabled = 1; - lttng_ht_add_unique_str(chan_ht, &uchan->node); DBG2("Channel %s created successfully", uchan->name); free(defattr); diff --git a/lttng-sessiond/ust-app.c b/lttng-sessiond/ust-app.c index 9c500481e..4f68a87ee 100644 --- a/lttng-sessiond/ust-app.c +++ b/lttng-sessiond/ust-app.c @@ -584,7 +584,7 @@ static int create_ust_channel(struct ust_app *app, ret = ustctl_create_channel(app->key.sock, ua_sess->handle, (struct lttng_ust_channel_attr *)&ua_chan->attr, &ua_chan->obj); if (ret < 0) { - DBG("Error creating channel %s for app (pid: %d, sock: %d) " + ERR("Creating channel %s for app (pid: %d, sock: %d) " "and session handle %d with ret %d", ua_chan->name, app->key.pid, app->key.sock, ua_sess->handle, ret); @@ -1062,8 +1062,6 @@ static struct ust_app_channel *create_ust_app_channel( goto error; } shadow_copy_channel(ua_chan, uchan); - - lttng_ht_add_unique_str(ua_sess->channels, &ua_chan->node); } else { ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node); } @@ -1073,6 +1071,8 @@ static struct ust_app_channel *create_ust_app_channel( goto error; } + lttng_ht_add_unique_str(ua_sess->channels, &ua_chan->node); + return ua_chan; error: -- 2.34.1