Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755953AbZGUTVe (ORCPT ); Tue, 21 Jul 2009 15:21:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755100AbZGUTVO (ORCPT ); Tue, 21 Jul 2009 15:21:14 -0400 Received: from mtagate7.de.ibm.com ([195.212.29.156]:61607 "EHLO mtagate7.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755872AbZGUTVK (ORCPT ); Tue, 21 Jul 2009 15:21:10 -0400 Message-Id: <20090721192058.392819645@de.ibm.com> References: <20090721191745.788551122@de.ibm.com> User-Agent: quilt/0.46-1 Date: Tue, 21 Jul 2009 21:17:47 +0200 From: Martin Schwidefsky To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Thomas Gleixner , john stultz , Martin Schwidefsky Subject: [RFC][patch 2/5] cleanup clocksource selection Content-Disposition: inline; filename=clocksource-queue.diff Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5870 Lines: 231 From: Martin Schwidefsky Introduce clocksource_dequeue & clocksource_update and move spinlock calls. clocksource_update does nothing for GENERIC_TIME=n since change_clocksource does nothing as well. Cc: Ingo Molnar Cc: Thomas Gleixner Cc: john stultz Signed-off-by: Martin Schwidefsky --- kernel/time/clocksource.c | 123 ++++++++++++++++++++++++++-------------------- 1 file changed, 70 insertions(+), 53 deletions(-) Index: linux-2.6/kernel/time/clocksource.c =================================================================== --- linux-2.6.orig/kernel/time/clocksource.c +++ linux-2.6/kernel/time/clocksource.c @@ -341,46 +341,25 @@ struct clocksource *clocksource_get_next return curr_clocksource; } -/** - * select_clocksource - Selects the best registered clocksource. - * - * Private function. Must hold clocksource_lock when called. - * - * Select the clocksource with the best rating, or the clocksource, - * which is selected by userspace override. - */ -static struct clocksource *select_clocksource(void) -{ - struct clocksource *next; - - if (list_empty(&clocksource_list)) - return NULL; - - if (clocksource_override) - next = clocksource_override; - else - next = list_entry(clocksource_list.next, struct clocksource, - list); - - if (next == curr_clocksource) - return NULL; - - return next; -} - /* * Enqueue the clocksource sorted by rating */ static int clocksource_enqueue(struct clocksource *c) { struct list_head *tmp, *entry = &clocksource_list; + unsigned long flags; + int rc; + spin_lock_irqsave(&clocksource_lock, flags); + rc = 0; list_for_each(tmp, &clocksource_list) { struct clocksource *cs; cs = list_entry(tmp, struct clocksource, list); - if (cs == c) - return -EBUSY; + if (cs == c) { + rc = -EBUSY; + goto out; + } /* Keep track of the place, where to insert */ if (cs->rating >= c->rating) entry = tmp; @@ -390,8 +369,23 @@ static int clocksource_enqueue(struct cl if (strlen(c->name) == strlen(override_name) && !strcmp(c->name, override_name)) clocksource_override = c; +out: + spin_unlock_irqrestore(&clocksource_lock, flags); + return rc; +} + +/* + * Dequeue a clocksource + */ +static void clocksource_dequeue(struct clocksource *cs) +{ + unsigned long flags; - return 0; + spin_lock_irqsave(&clocksource_lock, flags); + list_del(&cs->list); + if (clocksource_override == cs) + clocksource_override = NULL; + spin_unlock_irqrestore(&clocksource_lock, flags); } /** @@ -539,6 +533,25 @@ void clocksource_forward_now(void) } /** + * select_clocksource - Selects the best registered clocksource. + * + * Private function. Must hold clocksource_lock when called. + * + * Select the clocksource with the best rating, or the clocksource, + * which is selected by userspace override. + */ +static struct clocksource *select_clocksource(void) +{ + if (list_empty(&clocksource_list)) + return NULL; + + if (clocksource_override) + return clocksource_override; + + return list_entry(clocksource_list.next, struct clocksource, list); +} + +/** * change_clocksource - Swaps clocksources if a new one is available * * Accumulates current time interval and initializes new clocksource @@ -577,6 +590,23 @@ void change_clocksource(void) clock->name); */ } + +/** + * clocksource_update - Check if a better clocksource is available + */ +static void clocksource_update(void) +{ + struct clocksource *new; + unsigned long flags; + + spin_lock_irqsave(&clocksource_lock, flags); + new = select_clocksource(); + if (new) + next_clocksource = new; + spin_unlock_irqrestore(&clocksource_lock, flags); +} +#else /* CONFIG_GENERIC_TIME */ +static inline void clocksource_update(void) { } #endif /** @@ -587,16 +617,13 @@ void change_clocksource(void) */ int clocksource_register(struct clocksource *c) { - unsigned long flags; int ret; - spin_lock_irqsave(&clocksource_lock, flags); ret = clocksource_enqueue(c); - if (!ret) - next_clocksource = select_clocksource(); - spin_unlock_irqrestore(&clocksource_lock, flags); - if (!ret) + if (!ret) { + clocksource_update(); clocksource_check_watchdog(c); + } return ret; } EXPORT_SYMBOL(clocksource_register); @@ -607,14 +634,10 @@ EXPORT_SYMBOL(clocksource_register); */ void clocksource_change_rating(struct clocksource *cs, int rating) { - unsigned long flags; - - spin_lock_irqsave(&clocksource_lock, flags); - list_del(&cs->list); + clocksource_dequeue(cs); cs->rating = rating; clocksource_enqueue(cs); - next_clocksource = select_clocksource(); - spin_unlock_irqrestore(&clocksource_lock, flags); + clocksource_update(); } /** @@ -622,14 +645,8 @@ void clocksource_change_rating(struct cl */ void clocksource_unregister(struct clocksource *cs) { - unsigned long flags; - - spin_lock_irqsave(&clocksource_lock, flags); - list_del(&cs->list); - if (clocksource_override == cs) - clocksource_override = NULL; - next_clocksource = select_clocksource(); - spin_unlock_irqrestore(&clocksource_lock, flags); + clocksource_dequeue(cs); + clocksource_update(); } /** @@ -721,13 +738,13 @@ static ssize_t sysfs_override_clocksourc } /* Reselect, when the override name has changed */ - if (ovr != clocksource_override) { + if (ovr != clocksource_override) clocksource_override = ovr; - next_clocksource = select_clocksource(); - } spin_unlock_irq(&clocksource_lock); + clocksource_update(); + return ret; } -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- 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/