From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Tue, 5 Dec 2017 20:22:11 +0000 (-0500)
Subject: Clean-up: remove unneeded rcu_read_lock acquisition
X-Git-Tag: v2.11.0-rc1~415
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=ac883ec3865ef6eb92fea65ce3f88eec7da02692;p=lttng-tools.git

Clean-up: remove unneeded rcu_read_lock acquisition

create_channel_per_uid() must already be called while the
RCU reader lock is held since the buffer registry is being
accessed.

The only caller of create_channel_per_uid() is do_create_channel()
which, itself, documents that it must be called while holding the
RCU read lock.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 675283aa6..cb5ba6c48 100644
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -2925,7 +2925,6 @@ static int create_channel_per_uid(struct ust_app *app,
 		uint64_t chan_reg_key;
 		struct ust_registry_channel *chan_reg;
 
-		rcu_read_lock();
 		chan_reg_key = ua_chan->tracing_channel_id;
 
 		pthread_mutex_lock(&reg_uid->registry->reg.ust->lock);
@@ -2946,7 +2945,6 @@ static int create_channel_per_uid(struct ust_app *app,
 				ua_chan->key,
 				LTTNG_DOMAIN_UST,
 				ua_chan->attr.subbuf_size * ua_chan->attr.num_subbuf);
-		rcu_read_unlock();
 		if (cmd_ret != LTTNG_OK) {
 			ret = - (int) cmd_ret;
 			ERR("Failed to add channel to notification thread");