From c1567f813a9992a64f8d0f6cfb912c3922812c35 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 12 Feb 2019 13:04:12 +0100 Subject: PM-runtime: Fix __pm_runtime_set_status() race with runtime resume 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 Reviewed-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman --- drivers/base/power/runtime.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) (limited to 'drivers/base/power') diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index ac54f65b6d63..af23eb327f57 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -1106,6 +1106,22 @@ int __pm_runtime_set_status(struct device *dev, unsigned int status) 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 @@ -1124,12 +1140,6 @@ int __pm_runtime_set_status(struct device *dev, unsigned int status) 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; @@ -1182,6 +1192,8 @@ int __pm_runtime_set_status(struct device *dev, unsigned int status) device_links_read_unlock(idx); } + pm_runtime_enable(dev); + return error; } EXPORT_SYMBOL_GPL(__pm_runtime_set_status); -- cgit v1.2.3-59-g8ed1b