Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992527AbbEPBIi (ORCPT ); Fri, 15 May 2015 21:08:38 -0400 Received: from mail-la0-f49.google.com ([209.85.215.49]:33783 "EHLO mail-la0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934608AbbEPBIe (ORCPT ); Fri, 15 May 2015 21:08:34 -0400 MIME-Version: 1.0 In-Reply-To: <6356516.qkiSo3Mux2@vostro.rjw.lan> References: <1429750212-28659-1-git-send-email-jinqian@android.com> <1429750212-28659-3-git-send-email-jinqian@android.com> <6356516.qkiSo3Mux2@vostro.rjw.lan> Date: Fri, 15 May 2015 18:08:32 -0700 Message-ID: Subject: Re: [PATCH 2/3] power: increment wakeup_count when save_wakeup_count failed. From: Jin Qian To: "Rafael J. Wysocki" Cc: Len Brown , Pavel Machek , Greg Kroah-Hartman , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3134 Lines: 87 Some wakeup event happens every frequently between reading wakeup_count and writing back wakeup_count. They changed wakeup event count so writes fail and usespace doesn't continue to suspend. However, such occurrences are not counted in ws->wakeup_count. I spent quite sometime finding out the problematic wakeup event with inaccurate wakeup_count : ) Thanks, jin On Fri, May 15, 2015 at 5:34 PM, Rafael J. Wysocki wrote: > On Wednesday, April 22, 2015 05:50:11 PM Jin Qian wrote: >> user-space aborts suspend attempt if writing wakeup_count failed. >> Count the write failure towards wakeup_count. > > A use case, please? > >> Signed-off-by: Jin Qian >> --- >> drivers/base/power/wakeup.c | 17 +++++++++++++++++ >> 1 file changed, 17 insertions(+) >> >> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c >> index f24c622..bdb45f3 100644 >> --- a/drivers/base/power/wakeup.c >> +++ b/drivers/base/power/wakeup.c >> @@ -57,6 +57,8 @@ static LIST_HEAD(wakeup_sources); >> >> static DECLARE_WAIT_QUEUE_HEAD(wakeup_count_wait_queue); >> >> +static ktime_t last_read_time; >> + >> /** >> * wakeup_source_prepare - Prepare a new wakeup source for initialization. >> * @ws: Wakeup source to prepare. >> @@ -771,10 +773,15 @@ void pm_wakeup_clear(void) >> bool pm_get_wakeup_count(unsigned int *count, bool block) >> { >> unsigned int cnt, inpr; >> + unsigned long flags; >> >> if (block) { >> DEFINE_WAIT(wait); >> >> + spin_lock_irqsave(&events_lock, flags); >> + last_read_time = ktime_get(); >> + spin_unlock_irqrestore(&events_lock, flags); >> + >> for (;;) { >> prepare_to_wait(&wakeup_count_wait_queue, &wait, >> TASK_INTERRUPTIBLE); >> @@ -806,6 +813,7 @@ bool pm_save_wakeup_count(unsigned int count) >> { >> unsigned int cnt, inpr; >> unsigned long flags; >> + struct wakeup_source *ws; >> >> events_check_enabled = false; >> spin_lock_irqsave(&events_lock, flags); >> @@ -813,6 +821,15 @@ bool pm_save_wakeup_count(unsigned int count) >> if (cnt == count && inpr == 0) { >> saved_count = count; >> events_check_enabled = true; >> + } else { >> + rcu_read_lock(); >> + list_for_each_entry_rcu(ws, &wakeup_sources, entry) { >> + if (ws->active || >> + ktime_compare(ws->last_time, last_read_time) > 0) { >> + ws->wakeup_count++; >> + } >> + } >> + rcu_read_unlock(); >> } >> spin_unlock_irqrestore(&events_lock, flags); >> return events_check_enabled; >> > > -- > I speak only for myself. > Rafael J. Wysocki, Intel Open Source Technology Center. -- 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/