linux-kernel - Re: [PATCH 3/3] PM / Sleep: Make __pm_stay

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 15 Feb 2012 20:39:02 -0800
From:	Arve Hjønnevåg <arve@...roid.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] PM / Sleep: Make __pm_stay_awake() delete wakeup
 source timers

2012/2/15 Rafael J. Wysocki <rjw@...k.pl>:
> From: Rafael J. Wysocki <rjw@...k.pl>
>
> If __pm_stay_awake() is called after __pm_wakeup_event() for the same
> wakep source object before its timer expires, it won't cancel the
> timer, so the wakeup source will be deactivated from the timer
> function as scheduled by __pm_wakeup_event().  In that case
> __pm_stay_awake() doesn't have any effect beyond incrementing
> the wakeup source's event_count field, although it should cancel
> the timer and make the wakeup source stay active until __pm_relax()
> is called for it.
>
> Conversely, if __pm_wakeup_event() is called for a wakeup source
> that has been activated by __pm_stay_awake() before, it will set up
> the timer to deactivate the wakeup source, although it should leave
> it active until __pm_relax() is called for it.

We have many drivers that call wake_lock_timeout instead of
wake_unlock to cancel a previous wake_lock call. These drivers will
need to use two wakeup sources if __pm_wakeup_event does not always
set the timeout. I think it is better to have the state of the wakeup
source only depend on the last function you called, instead of that
last function being a noop in some cases.

-- 
Arve Hjønnevåg
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/