From d5d4db704b962773c03ee3beb3258b6450611e66 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 29 May 2007 16:34:52 -0400 Subject: [PATCH] USB: replace flush_workqueue with cancel_sync_work This patch (as912) replaces a couple of calls to flush_workqueue() with cancel_sync_work() and cancel_rearming_delayed_work(). Using a more directed approach allows us to avoid some nasty deadlocks. The prime example occurs when a first-level device (the parent is a root hub) is removed while at the same time the root hub gets a remote wakeup request. khubd would try to flush the autosuspend workqueue while holding the root-hub's lock, and the remote-wakeup workqueue routine would be waiting to lock the root hub. The patch also reorganizes the power management portion of usb_disconnect(), separating it out into its own routine. The autosuspend workqueue entry is cancelled immediately instead of waiting for the device's release routine. In addition, synchronization with the autosuspend thread is carried out even for root hubs (an oversight in the original code). Signed-off-by: Alan Stern Cc: Andrew Morton Cc: Greg KH Cc: Mark Lord Signed-off-by: Linus Torvalds --- drivers/usb/core/hcd.c | 2 +- drivers/usb/core/hub.c | 32 +++++++++++++++++++++++++------- drivers/usb/core/usb.c | 4 ---- 3 files changed, 26 insertions(+), 12 deletions(-) diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index e277258df382..8969e42434b9 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -1681,7 +1681,7 @@ void usb_remove_hcd(struct usb_hcd *hcd) spin_unlock_irq (&hcd_root_hub_lock); #ifdef CONFIG_PM - flush_workqueue(ksuspend_usb_wq); + cancel_work_sync(&hcd->wakeup_work); #endif mutex_lock(&usb_bus_list_lock); diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index caaa46f2dec7..24f10a19dbdb 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1158,6 +1158,30 @@ static void release_address(struct usb_device *udev) } } +#ifdef CONFIG_USB_SUSPEND + +static void usb_stop_pm(struct usb_device *udev) +{ + /* Synchronize with the ksuspend thread to prevent any more + * autosuspend requests from being submitted, and decrement + * the parent's count of unsuspended children. + */ + usb_pm_lock(udev); + if (udev->parent && !udev->discon_suspended) + usb_autosuspend_device(udev->parent); + usb_pm_unlock(udev); + + /* Stop any autosuspend requests already submitted */ + cancel_rearming_delayed_work(&udev->autosuspend); +} + +#else + +static inline void usb_stop_pm(struct usb_device *udev) +{ } + +#endif + /** * usb_disconnect - disconnect a device (usbcore-internal) * @pdev: pointer to device being disconnected @@ -1224,13 +1248,7 @@ void usb_disconnect(struct usb_device **pdev) *pdev = NULL; spin_unlock_irq(&device_state_lock); - /* Decrement the parent's count of unsuspended children */ - if (udev->parent) { - usb_pm_lock(udev); - if (!udev->discon_suspended) - usb_autosuspend_device(udev->parent); - usb_pm_unlock(udev); - } + usb_stop_pm(udev); put_device(&udev->dev); } diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index 80627b6a2bf9..4a6299bd0047 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -184,10 +184,6 @@ static void usb_release_dev(struct device *dev) udev = to_usb_device(dev); -#ifdef CONFIG_USB_SUSPEND - cancel_delayed_work(&udev->autosuspend); - flush_workqueue(ksuspend_usb_wq); -#endif usb_destroy_configuration(udev); usb_put_hcd(bus_to_hcd(udev->bus)); kfree(udev->product); -- 2.20.1