Re: [PATCH 1/4] s390/crypto: Replace cond_resched() with schedule()

[Heiko Carstens <hca@linux.ibm.com>]

On Tue, Jul 28, 2026 at 09:05:16AM +0200, Harald Freudenberger wrote:
> On 2026-07-27 18:24, Heiko Carstens wrote:
> > The comment for all cond_resched() calls in crypto code says that the
> > process should be scheduled away to avoid instant re-invocation of a
> > callback. This is not what cond_resched() would do or did.
> > 
> > Replace cond_resched() with a call to schedule() which comes closer, but
> > it looks more like this code wants an msleep() call.
> > 
> > Note that with [1] cond_resched() is always compiled away and becomes a
> > no-op.
> > 
> > [1] commit 7dadeaa6e851 ("sched: Further restrict the preemption modes")
> > 
> > Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
> > ---
> >  arch/s390/crypto/paes_s390.c  | 8 ++++----
> >  arch/s390/crypto/phmac_s390.c | 4 ++--
> >  2 files changed, 6 insertions(+), 6 deletions(-)

...

> > -			cond_resched();
> > +			schedule();
> >  			return -ENOSPC;
> >  		}
> >  		break;
> 
> Ok for me but we agreed to have all this code going via Herbert Xu.
> So please address this patch to Herbert and the crypto mailing list.
> And then I'll add my Reviewed-by.

Well, the main question still remains: why did the code use cond_resched()?

This doesn't make sense to me, at least when reading the comment. So to me
even the schedule() approach I proposed is questionable. Why didn't the code
use msleep() instead? Or can we just remove cond_resched() entirely without
any replacement?