This change will send a CHANGE event to udev with the DEAD environment variable set when the HC dies. I chose this instead of any of the other udev events because it's representing a state change in the host controller. The only other event that might have fit was OFFLINE, but that seems to be used for hot-removal and it implies the device could come ONLINE again. By notifying user space the appropriate policies can be applied. i.e., * Collect error logs. * Notify the user that USB is no longer functional. * Perform a graceful reboot. Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx> --- I wasn't able to find any good examples of other drivers sending a dead notification. Use an EVENT= format https://github.com/torvalds/linux/blob/master/drivers/acpi/dock.c#L302 https://github.com/torvalds/linux/blob/master/drivers/net/wireless/ath/wil6210/interrupt.c#L497 Uses SDEV_MEDIA_CHANGE= https://github.com/torvalds/linux/blob/master/drivers/scsi/scsi_lib.c#L2318 Uses ERROR=1. https://chromium.googlesource.com/chromiumos/third_party/kernel/+/7f6d8aec5803aac44192f03dce5637b66cda7abf/drivers/input/touchscreen/atmel_mxt_ts.c#1581 I'm not a fan because it doesn't signal what the error was. We could change the DEAD=1 event to maybe ERROR=1? Also where would be a good place to document this? Also thanks for the review. This is my first kernel patch so forgive me if I get the workflow wrong. Changes in v2: - Check that the root hub still exists before sending the uevent. - Ensure died_work has completed before deallocating. drivers/usb/core/hcd.c | 32 ++++++++++++++++++++++++++++++++ include/linux/usb/hcd.h | 1 + 2 files changed, 33 insertions(+) diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index 975d7c1288e3..7835f1a3647d 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -2343,6 +2343,27 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg) return status; } + +/** + * hcd_died_work - Workqueue routine for root-hub has died. + * @hcd: primary host controller for this root hub. + * + * Do not call with the shared_hcd. + * */ +static void hcd_died_work(struct work_struct *work) +{ + struct usb_hcd *hcd = container_of(work, struct usb_hcd, died_work); + + mutex_lock(&usb_bus_idr_lock); + + if (hcd->self.root_hub) + /* Notify user space that the host controller has died */ + kobject_uevent_env(&hcd->self.root_hub->dev.kobj, KOBJ_CHANGE, + (char *[]){ "DEAD=1", NULL }); + + mutex_unlock(&usb_bus_idr_lock); +} + /* Workqueue routine for root-hub remote wakeup */ static void hcd_resume_work(struct work_struct *work) { @@ -2488,6 +2509,13 @@ void usb_hc_died (struct usb_hcd *hcd) usb_kick_hub_wq(hcd->self.root_hub); } } + + /* Handle the case where this function gets called with a shared HCD */ + if (usb_hcd_is_primary_hcd(hcd)) + schedule_work(&hcd->died_work); + else + schedule_work(&hcd->primary_hcd->died_work); + spin_unlock_irqrestore (&hcd_root_hub_lock, flags); /* Make sure that the other roothub is also deallocated. */ } @@ -2555,6 +2583,8 @@ struct usb_hcd *__usb_create_hcd(const struct hc_driver *driver, INIT_WORK(&hcd->wakeup_work, hcd_resume_work); #endif + INIT_WORK(&hcd->died_work, hcd_died_work); + hcd->driver = driver; hcd->speed = driver->flags & HCD_MASK; hcd->product_desc = (driver->product_desc) ? driver->product_desc : @@ -2908,6 +2938,7 @@ int usb_add_hcd(struct usb_hcd *hcd, #ifdef CONFIG_PM cancel_work_sync(&hcd->wakeup_work); #endif + cancel_work_sync(&hcd->died_work); mutex_lock(&usb_bus_idr_lock); usb_disconnect(&rhdev); /* Sets rhdev to NULL */ mutex_unlock(&usb_bus_idr_lock); @@ -2968,6 +2999,7 @@ void usb_remove_hcd(struct usb_hcd *hcd) #ifdef CONFIG_PM cancel_work_sync(&hcd->wakeup_work); #endif + cancel_work_sync(&hcd->died_work); mutex_lock(&usb_bus_idr_lock); usb_disconnect(&rhdev); /* Sets rhdev to NULL */ diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h index 695931b03684..ae51d5bd1dfc 100644 --- a/include/linux/usb/hcd.h +++ b/include/linux/usb/hcd.h @@ -98,6 +98,7 @@ struct usb_hcd { #ifdef CONFIG_PM struct work_struct wakeup_work; /* for remote wakeup */ #endif + struct work_struct died_work; /* for dying */ /* * hardware info/state -- 2.21.0.392.gf8f6787159e-goog
