From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933331AbcHVXeb (ORCPT ); Mon, 22 Aug 2016 19:34:31 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:33254 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933305AbcHVXe2 (ORCPT ); Mon, 22 Aug 2016 19:34:28 -0400 From: Nicolai Stange To: Thomas Gleixner Cc: John Stultz , linux-kernel@vger.kernel.org, Nicolai Stange Subject: [RFC v4 21/22] clockevents: make setting of ->mult and ->mult_adjusted atomic Date: Tue, 23 Aug 2016 01:33:19 +0200 Message-Id: <20160822233320.4548-22-nicstange@gmail.com> X-Mailer: git-send-email 2.9.2 In-Reply-To: <20160822233320.4548-1-nicstange@gmail.com> References: <20160822233320.4548-1-nicstange@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In order to avoid races between setting a struct clock_event_device's ->mult_adjusted in clockevents_update_freq() and yet to be implemented updates triggered from the timekeeping core, the setting of ->mult and ->mult_adjusted should be made atomic. Protect the update in clockevents_update_freq() by locking the clockevents_lock spinlock. Frequency updates are expected to be done seldomly and thus, taking this subsystem lock should not have any impact on performance. Note that the call to tick_broadcast_update_freq() is also protected by this clockevents_lock and thus, this patch introduces the locking dependency clockevents_lock -> tick_broadcast_lock. Signed-off-by: Nicolai Stange --- kernel/time/clockevents.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 8a89b8a..ee7cd40 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -592,11 +592,11 @@ int clockevents_update_freq(struct clock_event_device *dev, u32 freq) unsigned long flags; int ret; - local_irq_save(flags); + raw_spin_lock_irqsave(&clockevents_lock, flags); ret = tick_broadcast_update_freq(dev, freq); if (ret == -ENODEV) ret = __clockevents_update_freq(dev, freq); - local_irq_restore(flags); + raw_spin_unlock_irqrestore(&clockevents_lock, flags); return ret; } -- 2.9.2