Messages in this thread | | | Date | Mon, 11 Mar 2013 14:55:51 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH] usb/core/devio.c: Don't use GFP_KERNEL while we cannot reset a storage device |
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On Tue, 12 Mar 2013, Ming Lei wrote:
> > In general it isn't, no. But usbfs uses the lock to prevent races with > > driver_disconnect() -- it is invalid to submit URBs after the > > disconnect routine has returned. > > If so, we may introduce another lock to avoid the race. > > So I think we may figure out to decrease the device lock > scope in devio.c, and most of ioctl commands might not require it > at all, then the problem addressed by the patch can be fixed too.
That might work. A mutex could be added to the dev_state structure. The mutex would be locked whenever an URB was being submitted and during driver_disconnect, and perhaps a few other places too, but not when memory was being allocated. The device itself would remain unlocked most of the time.
Alan Stern
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