[dm-devel] kmalloc after down_write?

Kevin Corry kevcorry at us.ibm.com
Fri Nov 19 18:21:15 UTC 2004


On Friday 19 November 2004 12:10 pm, Ming Zhang wrote:
> I am reading dm-snap.c and found that in register_snapshot(),
> http://lxr.linux.no/source/drivers/md/dm-snap.c?v=2.6.8.1#L159,
> the kmalloc is called with rwsem held. I am not sure if this is a good
> one since kmalloc may sleep as well.

It's a semaphore, not a spinlock. Sleeping is allowed while holding a 
semaphore, since other threads waiting on the semaphore are also rescheduled 
(instead of just spinning).

-- 
Kevin Corry
kevcorry at us.ibm.com
http://evms.sourceforge.net/




More information about the dm-devel mailing list