On Tuesday 05 February 2002 06:13, Mark McClelland wrote:
> Oliver Neukum wrote:
> >b) you are holding a spinlock or rwlock (does not apply to semaphores)
>
> I'm assuming that applies to the Big Kernel Lock too. If so, the V4L
> drivers need GFP_ATOMIC for the URBs they submit on open(), since
> videodev.c grabs the BKL before calling the open(), release(), or mmap()
> callbacks.
>
> Rather than change the drivers, I suggest that the BKL in this case be
> replaced with semaphore in struct video_device. Especially since most of
> the drivers vmalloc() a lot of memory during open(). Sleeping while
> holding the BKL is a Bad Thing, no?
Hi,
no it does not apply to the BKL. You can ignore it under this angle.
And at least open() has to grab the BKL as it would else race
with module unload and USB disconnect.
The BKL is specifically designed to allow sleeping.
Regards
Oliver
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