Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754687Ab1FMRPv (ORCPT ); Mon, 13 Jun 2011 13:15:51 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:33621 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753512Ab1FMRPu (ORCPT ); Mon, 13 Jun 2011 13:15:50 -0400 Subject: [PATCH] timerfd: fix wakeup of processes when timer is cancelled on clock change From: Max Asbock To: linux-kernel Cc: tglx , kay.sievers@vrfy.org, virtuoso@slind.org, johnstul Content-Type: text/plain Date: Mon, 13 Jun 2011 10:18:32 -0700 Message-Id: <1307985512.4710.41.camel@w-amax.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1705 Lines: 48 I have sent this before, perhaps it got lost in the noise. Currently processes waiting on cancelable timerfd timers are not woken up when the timers are canceled. When the system time is set the clock_was_set() function calls timerfd_clock_was_set() to cancel and wake up processes waiting on potential cancelable timerfd timers. However the wake up currently has no effect because in the case of timerfd_read it is dependent on ctx->ticks not being 0. timerfd_poll also requires ctx->ticks being non zero. As a consequence processes waiting on cancelable timers only get woken up when the timers expire. This patch fixes this by incrementing ctx->ticks before calling wake_up. Signed-off-by: Max Asbock --- --- linux-3.0-rc1/fs/timerfd.c +++ linux-3.0-rc1.timerfd/fs/timerfd.c @@ -61,7 +61,9 @@ static enum hrtimer_restart timerfd_tmrp /* * Called when the clock was set to cancel the timers in the cancel - * list. + * list. This will wake up processes waiting on these timers. The + * wake-up requires ctx->ticks to be non zero, therefore we increment + * it before calling wake_up_locked(). */ void timerfd_clock_was_set(void) { @@ -76,6 +78,7 @@ void timerfd_clock_was_set(void) spin_lock_irqsave(&ctx->wqh.lock, flags); if (ctx->moffs.tv64 != moffs.tv64) { ctx->moffs.tv64 = KTIME_MAX; + ctx->ticks++; wake_up_locked(&ctx->wqh); } spin_unlock_irqrestore(&ctx->wqh.lock, flags); -- Max -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/