Re: [PATCH 4/6] crypto: talitos - fix GFP flag usage

On Thu, 17 Jul 2008 10:51:43 -0500
Kumar Gala [off-list ref] wrote:

On Jul 17, 2008, at 10:27 AM, Kim Phillips wrote:

quoted

On Thu, 17 Jul 2008 07:26:14 -0500
Kumar Gala [off-list ref] wrote:

quoted

On Jul 17, 2008, at 7:17 AM, Herbert Xu wrote:

quoted

On Wed, Jul 16, 2008 at 06:33:45PM -0500, Kumar Gala wrote:

quoted

On Jul 16, 2008, at 6:22 PM, Kim Phillips wrote:

quoted

use GFP_ATOMIC when necessary; use atomic_t when allocating
submit_count.

why?

You mean why are atomics required? Yes that is a good question.

Yep. the commit message isn't explaining why, just what :)

In honouring requests that don't have the CRYPTO_TFM_REQ_MAY_SLEEP  
set,
afaict, it's the standard non-wait variant GFP that drivers use (see
the ixp4xx driver for e.g.).

so GFP_ATOMIC and atomic_t aren't related.  I can understand the need  
for GFP_ATOMIC, but I don't get why something needs to be declared  
atomic_t.

I see what the source of confusion is now; it appears I missed this
atomic_t clean-up when making the patchseries; the atomic_t fix belongs
in the previous "preempt overflow interrupts" patch (3/6).

atomic_t is needed for atomic operations which protect resource
contention on submit_count, which subsequently represents submission
slot availability on a particular SEC channel for multiple, potentially
simultaneous, users.

Kim