From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
Daniel Vetter <daniel@ffwll.ch>, Lukas Wunner <lukas@wunner.de>,
Andrzej Hajda <a.hajda@samsung.com>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
Lucas Stach <l.stach@pengutronix.de>,
Linus Walleij <linus.walleij@linaro.org>,
Thierry Reding <thierry.reding@gmail.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [PATCH 1/2] PM-runtime: Fix __pm_runtime_set_status() race with runtime resume
Date: Tue, 12 Feb 2019 13:04:12 +0100 [thread overview]
Message-ID: <1670239.00ZbddH1IV@aspire.rjw.lan> (raw)
In-Reply-To: <5510642.nRbR3bcduN@aspire.rjw.lan>
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Commit 4080ab083000 ("PM-runtime: Take suppliers into account in
__pm_runtime_set_status()") introduced a race condition that may
trigger if __pm_runtime_set_status() is used incorrectly (that is,
if it is called when PM-runtime is enabled for the target device
and working).
In that case, if the original PM-runtime status of the device is
RPM_SUSPENDED, a runtime resume of the device may occur after
__pm_runtime_set_status() has dropped its power.lock spinlock
and before deactivating its suppliers, so the suppliers may be
deactivated while the device is PM-runtime-active which may lead
to functional issues.
To avoid that, modify __pm_runtime_set_status() to check whether
or not PM-runtime is enabled for the device before activating its
suppliers (if the new status is RPM_ACTIVE) and either return an
error if that's the case or increment the device's disable_depth
counter to prevent PM-runtime from being enabled for it while
the remaining part of the function is running (disable_depth is
then decremented on the way out).
Fixes: 4080ab083000 ("PM-runtime: Take suppliers into account in __pm_runtime_set_status()")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/base/power/runtime.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -1129,6 +1129,22 @@ int __pm_runtime_set_status(struct devic
if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
return -EINVAL;
+ spin_lock_irq(&dev->power.lock);
+
+ /*
+ * Prevent PM-runtime from being enabled for the device or return an
+ * error if it is enabled already and working.
+ */
+ if (dev->power.runtime_error || dev->power.disable_depth)
+ dev->power.disable_depth++;
+ else
+ error = -EAGAIN;
+
+ spin_unlock_irq(&dev->power.lock);
+
+ if (error)
+ return error;
+
/*
* If the new status is RPM_ACTIVE, the suppliers can be activated
* upfront regardless of the current status, because next time
@@ -1147,12 +1163,6 @@ int __pm_runtime_set_status(struct devic
spin_lock_irq(&dev->power.lock);
- if (!dev->power.runtime_error && !dev->power.disable_depth) {
- status = dev->power.runtime_status;
- error = -EAGAIN;
- goto out;
- }
-
if (dev->power.runtime_status == status || !parent)
goto out_set;
@@ -1205,6 +1215,8 @@ int __pm_runtime_set_status(struct devic
device_links_read_unlock(idx);
}
+ pm_runtime_enable(dev);
+
return error;
}
EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
next prev parent reply other threads:[~2019-02-12 12:10 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 12:01 [PATCH 0/2] driver core: Fixes related to device links Rafael J. Wysocki
2019-02-12 12:04 ` Rafael J. Wysocki [this message]
2019-02-12 16:17 ` [PATCH 1/2] PM-runtime: Fix __pm_runtime_set_status() race with runtime resume Ulf Hansson
2019-02-12 16:28 ` Rafael J. Wysocki
2019-02-12 18:27 ` Ulf Hansson
2019-02-12 19:05 ` Rafael J. Wysocki
2019-02-12 20:14 ` Ulf Hansson
2019-02-12 12:08 ` [PATCH 2/2] driver core: Fix possible supplier PM-usage counter imbalance Rafael J. Wysocki
2019-02-12 21:02 ` Ulf Hansson
2019-02-12 22:08 ` Rafael J. Wysocki
2019-02-15 11:00 ` Jon Hunter
2019-02-15 11:57 ` Rafael J. Wysocki
2019-02-15 12:06 ` Rafael J. Wysocki
2019-02-15 13:21 ` Jon Hunter
2019-02-15 14:14 ` Jon Hunter
2019-02-15 14:37 ` Ulf Hansson
2019-02-15 16:44 ` Jon Hunter
2019-02-17 21:33 ` Rafael J. Wysocki
2019-02-18 12:12 ` Rafael J. Wysocki
2019-02-18 13:02 ` Jon Hunter
2019-02-18 22:14 ` Rafael J. Wysocki
2019-02-12 14:09 ` [PATCH 0/2] driver core: Fixes related to device links Greg Kroah-Hartman
2019-02-12 14:52 ` Ulf Hansson
2019-02-12 15:04 ` Rafael J. Wysocki
2019-02-12 15:06 ` Greg Kroah-Hartman
2019-02-12 16:20 ` Rafael J. Wysocki
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