From 4d769def244806562de1baa3acb39726131fbe6a Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 22 Feb 2013 16:34:22 -0800 Subject: [PATCH] usb: forbid memory allocation with I/O during bus reset If one storage interface or usb network interface(iSCSI case) exists in current configuration, memory allocation with GFP_KERNEL during usb_device_reset() might trigger I/O transfer on the storage interface itself and cause deadlock because the 'us->dev_mutex' is held in .pre_reset() and the storage interface can't do I/O transfer when the reset is triggered by other interface, or the error handling can't be completed if the reset is triggered by the storage itself (error handling path). Signed-off-by: Ming Lei Cc: "David S. Miller" Cc: Eric Dumazet Cc: David Decotigny Cc: Tom Herbert Cc: Ingo Molnar Cc: Jens Axboe Cc: Minchan Kim Cc: Alan Stern Cc: Oliver Neukum Reviewed-by: Jiri Kosina Cc: Mel Gorman Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko Cc: Ingo Molnar Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/usb/core/hub.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 1775ad471edd..5480352f984d 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -5177,6 +5177,7 @@ int usb_reset_device(struct usb_device *udev) { int ret; int i; + unsigned int noio_flag; struct usb_host_config *config = udev->actconfig; if (udev->state == USB_STATE_NOTATTACHED || @@ -5186,6 +5187,17 @@ int usb_reset_device(struct usb_device *udev) return -EINVAL; } + /* + * Don't allocate memory with GFP_KERNEL in current + * context to avoid possible deadlock if usb mass + * storage interface or usbnet interface(iSCSI case) + * is included in current configuration. The easist + * approach is to do it for every device reset, + * because the device 'memalloc_noio' flag may have + * not been set before reseting the usb device. + */ + noio_flag = memalloc_noio_save(); + /* Prevent autosuspend during the reset */ usb_autoresume_device(udev); @@ -5230,6 +5242,7 @@ int usb_reset_device(struct usb_device *udev) } usb_autosuspend_device(udev); + memalloc_noio_restore(noio_flag); return ret; } EXPORT_SYMBOL_GPL(usb_reset_device); -- 2.20.1