Re: [PATCH] devfs v212 available

Alexander Viro (viro@math.psu.edu)
Mon, 13 May 2002 00:10:37 -0400 (EDT)


On Sun, 12 May 2002, Richard Gooch wrote:

> OK, I've had a look. There is indeed a race there. While it is safe
> against module unloading, it isn't safe against removal of entries
> from the directory. I'm considering some different options to fix this
> (one is simple and obvious, the other will be a little more
> efficient).
>
> Question: can invalidate_device() and the bdops methods
> check_media_change() and revalidate() be called with a lock held?

Erm... Depends on the nature of lock. Spinlocks are out of question,
obviously (at the very least we reread partition table if disk had been
changed and you can't make that nonblocking ;-). Semaphore might work,
but I would be very careful with deadlocks - the same rereading partition
table could add or remove devfs entries.

Could you describe what are you trying to achieve in the callers of
check_disc_changed()? I'd been unable to deduce that from code and
some comments would be very welcome.

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