Re: [PATCH 01/12] usbnet: introduce usbnet 3 command helpers

On Mon, 15 Oct 2012, Oliver Neukum wrote:

On Friday 12 October 2012 11:29:49 Alan Stern wrote:

quoted

On Fri, 12 Oct 2012, Oliver Neukum wrote:

quoted

quoted

First we have workqueues. bas-gigaset is a good example.
The driver kills a scheduled work in pre_reset(). If this is done synchronously
the driver may need to wait for a memory allocation inside the work.
In principle we could provide a workqueue limited to GFP_NOIO. Is that worth
it, or do we just check?

The work routine could set the GFP mask upon entry and exit.  Then a 
separate workqueue wouldn't be needed.

Well, yes. But if we have to touch the code we might just as well use GFP-NOIO

Depends on what the code does.  If it does very little requiring memory 
allocation then yes, you could simply use GFP_NOIO.  But if it calls 
lots of other routines that all do their own allocation, setting the 
mask will be better.

quoted

quoted

I am afraid there is no generic solution in the last two cases. What do you think?

The other contexts must also set the GFP mask.  Unfortunately, this has 
to be done case-by-case.

This raises a question. If we do the port-power-off stuff, does reset_resume() of every
device under the depowered port have to be called?

Certainly.

 If so, we cannot exclude vendor
specific drivers from the audit, can we?

True.  But hasn't that always been the case?  A device could need a 
vendor-specific driver for one interface while another interface uses a 
standard mass-storage protocol.

Alan Stern

--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html