[02/20] usb: host: xhci: check DYING state earlier

From: Felipe Balbi <felipe.balbi@linux.intel.com>
To: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Linux USB <linux-usb@vger.kernel.org>,
	Alan Stern <stern@rowland.harvard.edu>
Subject: [02/20] usb: host: xhci: check DYING state earlier
Date: Tue, 17 Apr 2018 10:07:43 +0300	[thread overview]
Message-ID: <87zi22joow.fsf@linux.intel.com> (raw)

Hi,

Mathias Nyman <mathias.nyman@linux.intel.com> writes:
> On 16.04.2018 15:29, Felipe Balbi wrote:
>> Instead of allocating urb priv and, maybe, bail out due to xhci being
>> in DYING state, we can move the check earlier and avoid the memory
>> allocation altogether.
>
> This also moves checking for DYING outside the lock.
>
> Most cases set DYING with lock held, so if we first get the lock before
> checking DYING we have a better chance of not being in the process of dying.

pretty sure that's atomic, though.

> Small thing, but so is this cleanup, so not sure its worth the change

Look at the result. With this change we don't need to take a lock,
allocate memory, search for endpoint index, search for endpoint
state. All of those are needed for proper operation of the function, but
if the controller has already died, there's no point in going any
further.