linux-kernel - [PATCH tip/core/rcu 04/19] rcu: Allow processing deferred QSes for exiting RCU-preempt readers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180829222047.319-4-paulmck@linux.vnet.ibm.com>
Date:   Wed, 29 Aug 2018 15:20:32 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 04/19] rcu: Allow processing deferred QSes for exiting RCU-preempt readers

If an RCU-preempt read-side critical section is exiting, that is,
->rcu_read_lock_nesting is negative, then it is a good time to look
at the possibility of reporting deferred quiescent states.  This
commit therefore updates the checks in rcu_preempt_need_deferred_qs()
to allow exiting critical sections to report deferred quiescent states.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/tree_plugin.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 542791361908..24c209676d20 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -602,7 +602,7 @@ static bool rcu_preempt_need_deferred_qs(struct task_struct *t)
 {
 	return (this_cpu_ptr(&rcu_preempt_data)->deferred_qs ||
 		READ_ONCE(t->rcu_read_unlock_special.s)) &&
-	       !t->rcu_read_lock_nesting;
+	       t->rcu_read_lock_nesting <= 0;
 }
 
 /*
-- 
2.17.1