From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Waiman Long <longman@redhat.com>,
"Paul E . McKenney" <paulmck@linux.ibm.com>,
Sasha Levin <sashal@kernel.org>,
rcu@vger.kernel.org
Subject: [PATCH AUTOSEL 5.2 101/249] rcu: Force inlining of rcu_read_lock()
Date: Mon, 15 Jul 2019 09:44:26 -0400 [thread overview]
Message-ID: <20190715134655.4076-101-sashal@kernel.org> (raw)
In-Reply-To: <20190715134655.4076-1-sashal@kernel.org>
From: Waiman Long <longman@redhat.com>
[ Upstream commit 6da9f775175e516fc7229ceaa9b54f8f56aa7924 ]
When debugging options are turned on, the rcu_read_lock() function
might not be inlined. This results in lockdep's print_lock() function
printing "rcu_read_lock+0x0/0x70" instead of rcu_read_lock()'s caller.
For example:
[ 10.579995] =============================
[ 10.584033] WARNING: suspicious RCU usage
[ 10.588074] 4.18.0.memcg_v2+ #1 Not tainted
[ 10.593162] -----------------------------
[ 10.597203] include/linux/rcupdate.h:281 Illegal context switch in
RCU read-side critical section!
[ 10.606220]
[ 10.606220] other info that might help us debug this:
[ 10.606220]
[ 10.614280]
[ 10.614280] rcu_scheduler_active = 2, debug_locks = 1
[ 10.620853] 3 locks held by systemd/1:
[ 10.624632] #0: (____ptrval____) (&type->i_mutex_dir_key#5){.+.+}, at: lookup_slow+0x42/0x70
[ 10.633232] #1: (____ptrval____) (rcu_read_lock){....}, at: rcu_read_lock+0x0/0x70
[ 10.640954] #2: (____ptrval____) (rcu_read_lock){....}, at: rcu_read_lock+0x0/0x70
These "rcu_read_lock+0x0/0x70" strings are not providing any useful
information. This commit therefore forces inlining of the rcu_read_lock()
function so that rcu_read_lock()'s caller is instead shown.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/rcupdate.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index b25d20822e75..3508f4508a11 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -586,7 +586,7 @@ static inline void rcu_preempt_sleep_check(void) { }
* read-side critical sections may be preempted and they may also block, but
* only when acquiring spinlocks that are subject to priority inheritance.
*/
-static inline void rcu_read_lock(void)
+static __always_inline void rcu_read_lock(void)
{
__rcu_read_lock();
__acquire(RCU);
--
2.20.1
parent reply other threads:[~2019-07-15 15:11 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20190715134655.4076-1-sashal@kernel.org>]
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