From: Rafael J. Wysocki <rafael.j.wyso...@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.wyso...@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);