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Revert "PM: runtime: Update device status before letting suppliers suspend"

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Revert commit 44cc89f764 ("PM: runtime: Update device status
before letting suppliers suspend") that introduced a race condition
into __rpm_callback() which allowed a concurrent rpm_resume() to
run and resume the device prematurely after its status had been
changed to RPM_SUSPENDED by __rpm_callback().

Fixes: 44cc89f764 ("PM: runtime: Update device status before letting suppliers suspend")
Link: https://lore.kernel.org/linux-pm/24dfb6fc-5d54-6ee2-9195-26428b7ecf8a@intel.com/
Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: 4.10+ <stable@vger.kernel.org> # 4.10+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Rafael J. Wysocki 2021-03-19 15:47:25 +01:00
parent 1e28eed176
commit 0cab893f40
1 changed files with 25 additions and 37 deletions
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62
drivers/base/power/runtime.c
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@ -325,22 +325,22 @@ static void rpm_put_suppliers(struct device *dev)
static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
bool use_links = dev->power.links_count > 0;
bool get = false;
int retval, idx;
bool put;
bool use_links = dev->power.links_count > 0;
if (dev->power.irq_safe) {
spin_unlock(&dev->power.lock);
} else if (!use_links) {
spin_unlock_irq(&dev->power.lock);
} else {
get = dev->power.runtime_status == RPM_RESUMING;
spin_unlock_irq(&dev->power.lock);
/* Resume suppliers if necessary. */
if (get) {
/*
* Resume suppliers if necessary.
*
* The device's runtime PM status cannot change until this
* routine returns, so it is safe to read the status outside of
* the lock.
*/
if (use_links && dev->power.runtime_status == RPM_RESUMING) {
idx = device_links_read_lock();
retval = rpm_get_suppliers(dev);
@ -355,36 +355,24 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
if (dev->power.irq_safe) {
spin_lock(&dev->power.lock);
return retval;
}
} else {
/*
* If the device is suspending and the callback has returned
* success, drop the usage counters of the suppliers that have
* been reference counted on its resume.
*
* Do that if resume fails too.
*/
if (use_links
&& ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
|| (dev->power.runtime_status == RPM_RESUMING && retval))) {
idx = device_links_read_lock();
spin_lock_irq(&dev->power.lock);
fail:
rpm_put_suppliers(dev);
if (!use_links)
return retval;
/*
* If the device is suspending and the callback has returned success,
* drop the usage counters of the suppliers that have been reference
* counted on its resume.
*
* Do that if the resume fails too.
*/
put = dev->power.runtime_status == RPM_SUSPENDING && !retval;
if (put)
__update_runtime_status(dev, RPM_SUSPENDED);
else
put = get && retval;
if (put) {
spin_unlock_irq(&dev->power.lock);
idx = device_links_read_lock();
fail:
rpm_put_suppliers(dev);
device_links_read_unlock(idx);
device_links_read_unlock(idx);
}
spin_lock_irq(&dev->power.lock);
}