linux-kernel - Re: [PATCH 2/3] PM / Runtime: Don't run callbacks under lock for power.irq

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]

Message-ID: <87oby66ejr.fsf@ti.com>
Date:	Mon, 26 Sep 2011 16:59:20 -0700
From:	Kevin Hilman <khilman@...com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Linux-sh list" <linux-sh@...r.kernel.org>,
	Magnus Damm <magnus.damm@...il.com>, jean.pihet@...oldbits.com,
	Ming Lei <tom.leiming@...il.com>
Subject: Re: [PATCH 2/3] PM / Runtime: Don't run callbacks under lock for power.irq_safe set

"Rafael J. Wysocki" <rjw@...k.pl> writes:

> From: Rafael J. Wysocki <rjw@...k.pl>
>
> The rpm_suspend() and rpm_resume() routines execute subsystem or PM
> domain callbacks under power.lock if power.irq_safe is set for the
> given device.  This is inconsistent with that rpm_idle() does after
> commit 02b2677 (PM / Runtime: Allow _put_sync() from
> interrupts-disabled context) and is problematic for subsystems and PM
> domains wanting to use power.lock for synchronization in their
> runtime PM callbacks.
>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>

The part described here looks right, and is much better for consistency.

Reviewed-by: Kevin Hilman <khilman@...com>

but...

[...]

> @@ -347,6 +353,15 @@ static int rpm_suspend(struct device *de
>  			goto out;
>  		}
>  
> +		if (dev->power.irq_safe) {
> +			spin_unlock(&dev->power.lock);
> +
> +			cpu_relax();
> +
> +			spin_lock(&dev->power.lock);
> +			goto repeat;
> +		}
> +


... AFAICT, this isn't directly related to the problem described in the
changelog (or at least I didn't find it obvious), and probably deserves
a comment in the code as well.

Thanks,

Kevin
--
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/