This is a note to let you know that I've just added the patch titled
ARM: at91: pm: fix imbalanced reference counter for ethernet devices
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-at91-pm-fix-imbalanced-reference-counter-for-eth.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 75f4fa5c26ca33edaf433a9b1a10eb2206612616
Author: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
Date: Thu May 18 09:25:11 2023 +0300
ARM: at91: pm: fix imbalanced reference counter for ethernet devices
[ Upstream commit ccd4923d18d5698a5910d516646ce125b9155d47 ]
The of_find_device_by_node() function is returning a struct platform_device
object with the embedded struct device member's reference counter
incremented. This needs to be dropped when done with the platform device
returned by of_find_device_by_node().
at91_pm_eth_quirk_is_valid() calls of_find_device_by_node() on
suspend and resume path. On suspend it calls of_find_device_by_node() and
on resume and failure paths it drops the counter of
struct platform_device::dev.
In case ethernet device may not wakeup there is a put_device() on
at91_pm_eth_quirk_is_valid() which is wrong as it colides with
put_device() on resume path leading to the reference counter of struct
device embedded in struct platform_device to be messed, stack trace to be
displayed (after 5 consecutive suspend/resume cycles) and execution to
hang.
Along with this the error path of at91_pm_config_quirks() had been also
adapted to decrement propertly the reference counter of struct device
embedded in struct platform_device.
Fixes: b7fc72c63399 ("ARM: at91: pm: add quirks for pm")
Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230518062511.2988500-1-claudiu.beznea@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 60dc56d8acfb9..437dd0352fd44 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -334,16 +334,14 @@ static bool at91_pm_eth_quirk_is_valid(struct at91_pm_quirk_eth *eth)
pdev = of_find_device_by_node(eth->np);
if (!pdev)
return false;
+ /* put_device(eth->dev) is called at the end of suspend. */
eth->dev = &pdev->dev;
}
/* No quirks if device isn't a wakeup source. */
- if (!device_may_wakeup(eth->dev)) {
- put_device(eth->dev);
+ if (!device_may_wakeup(eth->dev))
return false;
- }
- /* put_device(eth->dev) is called at the end of suspend. */
return true;
}
@@ -439,14 +437,14 @@ static int at91_pm_config_quirks(bool suspend)
pr_err("AT91: PM: failed to enable %s clocks\n",
j == AT91_PM_G_ETH ? "geth" : "eth");
}
- } else {
- /*
- * Release the reference to eth->dev taken in
- * at91_pm_eth_quirk_is_valid().
- */
- put_device(eth->dev);
- eth->dev = NULL;
}
+
+ /*
+ * Release the reference to eth->dev taken in
+ * at91_pm_eth_quirk_is_valid().
+ */
+ put_device(eth->dev);
+ eth->dev = NULL;
}
return ret;
