From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 03/11] rcu: Use lockdep rather than comment to enforce lock held
Date: Mon, 9 Dec 2019 20:26:21 -0800 [thread overview]
Message-ID: <20191210042629.3808-3-paulmck@kernel.org> (raw)
In-Reply-To: <20191210042606.GA3624@paulmck-ThinkPad-P72>
From: "Paul E. McKenney" <paulmck@kernel.org>
The rcu_preempt_check_blocked_tasks() function has a comment
that states that the rcu_node structure's ->lock must be held,
which might be informative, but which carries little weight if
not read. This commit therefore removes this comment in favor of
raw_lockdep_assert_held_rcu_node(), which will complain quite
visibly if the required lock is not held.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree_plugin.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index fe5f448..ed54d36 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -648,8 +648,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
* Check that the list of blocked tasks for the newly completed grace
* period is in fact empty. It is a serious bug to complete a grace
* period that still has RCU readers blocked! This function must be
- * invoked -before- updating this rnp's ->gp_seq, and the rnp's ->lock
- * must be held by the caller.
+ * invoked -before- updating this rnp's ->gp_seq.
*
* Also, if there are blocked tasks on the list, they automatically
* block the newly created grace period, so set up ->gp_tasks accordingly.
@@ -659,6 +658,7 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
struct task_struct *t;
RCU_LOCKDEP_WARN(preemptible(), "rcu_preempt_check_blocked_tasks() invoked with preemption enabled!!!\n");
+ raw_lockdep_assert_held_rcu_node(rnp);
if (WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp)))
dump_blkd_tasks(rnp, 10);
if (rcu_preempt_has_tasks(rnp) &&
--
2.9.5
next prev parent reply other threads:[~2019-12-10 4:26 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 4:26 [PATCH tip/core/rcu 0/11] Preemptible-RCU updates for v5.6 Paul E. McKenney
2019-12-10 4:26 ` [PATCH tip/core/rcu 01/11] rcu/nocb: Fix dump_tree hierarchy print always active paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 02/11] rcu: Avoid data-race in rcu_gp_fqs_check_wake() paulmck
2019-12-10 4:26 ` paulmck [this message]
2019-12-10 4:26 ` [PATCH tip/core/rcu 04/11] rcu: Make PREEMPT_RCU be a modifier to TREE_RCU paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 05/11] rcu: Use CONFIG_PREEMPTION where appropriate paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 06/11] rcu: Rename some instance of CONFIG_PREEMPTION to CONFIG_PREEMPT_RCU paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 07/11] rcu: Clear .exp_hint only when deferred quiescent state has been reported paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 08/11] rcu: Clear ->rcu_read_unlock_special only once paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 09/11] rcu: Use READ_ONCE() for ->expmask in rcu_read_unlock_special() paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 10/11] rcu: Provide wrappers for uses of ->rcu_read_lock_nesting paulmck
2019-12-10 4:26 ` [PATCH tip/core/rcu 11/11] rcu: Avoid tick_dep_set_cpu() misordering paulmck
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