Re: [PATCH/RFC 2.6.21 3/5] ehca: completion queue: remove use of do_mmap()

On Thu, Jan 11, 2007 at 01:40:54PM -0600, Nathan Lynch wrote:

Christoph Hellwig wrote:

quoted

On Thu, Jan 11, 2007 at 08:08:36PM +0100, Hoang-Nam Nguyen wrote:

quoted

 	spin_lock_irqsave(&ehca_cq_idr_lock, flags);
 	while (my_cq->nr_callbacks)
 		yield();

Calling yield is a very bad idea in general.  You should probably
add a waitqueue that gets woken when nr_callbacks reaches zero to
sleep effectively here.

Isn't that code outright buggy?  Calling into the scheduler with a
spinlock held and local interrupts disabled...

Umm, yes - of course.  I missed the spin_lock_irqsave line just above.