From: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, mingo@redhat.com, Waiman.Long@hpe.com,
Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Subject: [PATCH v2] locking/qspinlock: Use __this_cpu_dec instead
Date: Tue, 14 Jun 2016 14:37:27 +0800 [thread overview]
Message-ID: <1465886247-3773-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> (raw)
queued_spin_lock_slowpath should not worry about another
queued_spin_lock_slowpath which runs in interrupt changes node->count by
accident because node->count keeps the same value everytime we
enter/leave queued_spin_lock_slowpath.
On some archs this_cpu_dec will save/restore irq flags, this will give a
heavy work load. Lets use __this_cpu_dec instead.
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
---
change from v1:
replace this_cpu_ptr with __this_cpu_dec
---
kernel/locking/qspinlock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 99f31e4..9fd1a1e 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -492,7 +492,7 @@ release:
/*
* release the node
*/
- this_cpu_dec(mcs_nodes[0].count);
+ __this_cpu_dec(mcs_nodes[0].count);
}
EXPORT_SYMBOL(queued_spin_lock_slowpath);
--
1.9.1
next reply other threads:[~2016-06-14 6:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 6:37 Pan Xinhui [this message]
2016-06-27 12:56 ` [tip:locking/core] locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec() tip-bot for Pan Xinhui
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