Kevin Hilman <khilman@xxxxxx> writes: [...] > If the device bus type's or driver's ->probe() or ->remove() > callback runs pm_runtime_suspend() or pm_runtime_idle() or their > asynchronous counterparts, they will fail returning -EAGAIN, because > the device's usage counter is incremented by the core before > executing ->probe() and ->remove(). Still, it may be desirable to > suspend the device as soon as ->probe() or ->remove() has finished, > so the PM core uses pm_runtime_idle_sync() to invoke the > subsystem-level idle callback for the device at that time. [...] > Another curiosity is that, contrary to the above documentation, there is > no usage_count increment before the bus/driver ->remove() (although > there is a _get_sync/_put_sync around the sysfs_remove and notifier just > before the bus/driver->remove(). OK, so the ->probe() part has been explained and makes sense, but I would expect ->remove() to be similarily protected (as the documentation states.) But that is not the case. Is that a bug? If so, patch below makes the code match the documentation. Kevin >From eef73ab2feb203bacb57dc35862f2a9969b61593 Mon Sep 17 00:00:00 2001 From: Kevin Hilman <khilman@xxxxxx> Date: Fri, 1 Jul 2011 07:37:47 -0700 Subject: [PATCH] driver core: prevent runtime PM races with ->remove() Runtime PM Documentation states that the runtime PM usage count is incremented during driver ->probe() and ->remove(). This is designed to prevent driver runtime PM races with subsystems which may initiate runtime PM transitions before during and after drivers are loaded. Current code increments the usage_count during ->probe() but not during ->remove(). This patch fixes the ->remove() part and makes the code match the documentation. Signed-off-by: Kevin Hilman <khilman@xxxxxx> --- drivers/base/dd.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 6658da7..47e079d 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -329,13 +329,13 @@ static void __device_release_driver(struct device *dev) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_UNBIND_DRIVER, dev); - - pm_runtime_put_sync(dev); - if (dev->bus && dev->bus->remove) dev->bus->remove(dev); else if (drv->remove) drv->remove(dev); + + pm_runtime_put_sync(dev); + devres_release_all(dev); dev->driver = NULL; klist_remove(&dev->p->knode_driver); -- 1.7.4 _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
