From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932872Ab3DYUeh (ORCPT ); Thu, 25 Apr 2013 16:34:37 -0400 Received: from www.linutronix.de ([62.245.132.108]:45978 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758773Ab3DYUbq (ORCPT ); Thu, 25 Apr 2013 16:31:46 -0400 Message-Id: <20130425143435.762417789@linutronix.de> User-Agent: quilt/0.48-1 Date: Thu, 25 Apr 2013 20:31:44 -0000 From: Thomas Gleixner To: LKML Cc: John Stultz , Ingo Molnar , Magnus Damm Subject: [patch 04/15] clocksource: Add module refcount References: <20130425142452.908423538@linutronix.de> Content-Disposition: inline; filename=clocksource-add-module-refcount.patch X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a module refcount, so the current clocksource cannot be removed unconditionally. Signed-off-by: Thomas Gleixner --- include/linux/clocksource.h | 3 +++ kernel/time/timekeeping.c | 15 ++++++++++----- 2 files changed, 13 insertions(+), 5 deletions(-) Index: tip/include/linux/clocksource.h =================================================================== --- tip.orig/include/linux/clocksource.h +++ tip/include/linux/clocksource.h @@ -21,6 +21,7 @@ /* clocksource cycle base type */ typedef u64 cycle_t; struct clocksource; +struct module; #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA #include @@ -162,6 +163,7 @@ extern u64 timecounter_cyc2time(struct t * @suspend: suspend function for the clocksource, if necessary * @resume: resume function for the clocksource, if necessary * @cycle_last: most recent cycle counter value seen by ::read() + * @owner: module reference */ struct clocksource { /* @@ -195,6 +197,7 @@ struct clocksource { cycle_t cs_last; cycle_t wd_last; #endif + struct module *owner; } ____cacheline_aligned; /* Index: tip/kernel/time/timekeeping.c =================================================================== --- tip.orig/kernel/time/timekeeping.c +++ tip/kernel/time/timekeeping.c @@ -627,11 +627,16 @@ static int change_clocksource(void *data write_seqcount_begin(&timekeeper_seq); timekeeping_forward_now(tk); - if (!new->enable || new->enable(new) == 0) { - old = tk->clock; - tk_setup_internals(tk, new); - if (old->disable) - old->disable(old); + if (try_module_get(new->owner)) { + if (!new->enable || new->enable(new) == 0) { + old = tk->clock; + tk_setup_internals(tk, new); + if (old->disable) + old->disable(old); + module_put(old->owner); + } else { + module_put(new->owner); + } } timekeeping_update(tk, true, true);