linux-kernel - [PATCH] PCI / PM: Block races between runtime PM and system sleep

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-next>] [day] [month] [year] [list]

Message-Id: <201106192149.19401.rjw@sisk.pl>
Date:	Sun, 19 Jun 2011 21:49:19 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: [PATCH] PCI / PM: Block races between runtime PM and system sleep

From: Rafael J. Wysocki <rjw@...k.pl>

After commit e8665002477f0278f84f898145b1f141ba26ee26
(PM: Allow pm_runtime_suspend() to succeed during system suspend) it
is possible that a device resumed by the pm_runtime_resume(dev) in
pci_pm_prepare() will be suspended immediately from a work item,
timer function or otherwise, defeating the very purpose of calling
pm_runtime_resume(dev) from there.  To prevent that from happening
it is necessary to increment the runtime PM usage counter of the
device by replacing pm_runtime_resume() with pm_runtime_get_sync().
Moreover, the incremented runtime PM usage counter has to be
decremented by the corresponding pci_pm_complete(), via
pm_runtime_put_noidle().

Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
Cc: stable@...nel.org
---
 drivers/pci/pci-driver.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/pci/pci-driver.c
===================================================================
--- linux-2.6.orig/drivers/pci/pci-driver.c
+++ linux-2.6/drivers/pci/pci-driver.c
@@ -624,7 +624,7 @@ static int pci_pm_prepare(struct device
 	 * system from the sleep state, we'll have to prevent it from signaling
 	 * wake-up.
 	 */
-	pm_runtime_resume(dev);
+	pm_runtime_get_sync(dev);
 
 	if (drv && drv->pm && drv->pm->prepare)
 		error = drv->pm->prepare(dev);
@@ -638,6 +638,8 @@ static void pci_pm_complete(struct devic
 
 	if (drv && drv->pm && drv->pm->complete)
 		drv->pm->complete(dev);
+
+	pm_runtime_put_noidle(dev);
 }
 
 #else /* !CONFIG_PM_SLEEP */
--
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/