Re: [PATCH v2 1/4] s390/crypto: Replace cond_resched() with msleep(1)

[Harald Freudenberger <freude@linux.ibm.com>]

On 2026-07-28 17:04, Heiko Carstens wrote:
> With [1] cond_resched() is always compiled away and becomes a no-op.
> 
> The comments for all cond_resched() calls in crypto code however 
> indicate
> that the current process should be scheduled away to avoid instant
> re-invocation of a callback. This is not what cond_resched() would do 
> or
> did.
> 
> Instead of just removing the cond_resched() calls, replace them with
> msleep() calls, as suggested by Holger Dengler. This forces the current
> task to be scheduled away (sleeps) like originally intended.
> 
> [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(-)
> 
> diff --git a/arch/s390/crypto/paes_s390.c 
> b/arch/s390/crypto/paes_s390.c
> index 8cfe6166c193..511cb6105436 100644
> --- a/arch/s390/crypto/paes_s390.c
> +++ b/arch/s390/crypto/paes_s390.c
> @@ -555,7 +555,7 @@ static int ecb_paes_do_one_request(struct
> crypto_engine *engine, void *areq)
>  		 * To avoid immediately re-invocation of this callback,
>  		 * tell the scheduler to voluntarily give up the CPU here.
>  		 */
> -		cond_resched();
> +		msleep(1);
>  		pr_debug("rescheduling request\n");
>  		return -ENOSPC;
>  	} else if (rc) {
> @@ -821,7 +821,7 @@ static int cbc_paes_do_one_request(struct
> crypto_engine *engine, void *areq)
>  		 * To avoid immediately re-invocation of this callback,
>  		 * tell the scheduler to voluntarily give up the CPU here.
>  		 */
> -		cond_resched();
> +		msleep(1);
>  		pr_debug("rescheduling request\n");
>  		return -ENOSPC;
>  	} else if (rc) {
> @@ -1129,7 +1129,7 @@ static int ctr_paes_do_one_request(struct
> crypto_engine *engine, void *areq)
>  		 * To avoid immediately re-invocation of this callback,
>  		 * tell the scheduler to voluntarily give up the CPU here.
>  		 */
> -		cond_resched();
> +		msleep(1);
>  		pr_debug("rescheduling request\n");
>  		return -ENOSPC;
>  	} else if (rc) {
> @@ -1572,7 +1572,7 @@ static int xts_paes_do_one_request(struct
> crypto_engine *engine, void *areq)
>  		 * To avoid immediately re-invocation of this callback,
>  		 * tell the scheduler to voluntarily give up the CPU here.
>  		 */
> -		cond_resched();
> +		msleep(1);
>  		pr_debug("rescheduling request\n");
>  		return -ENOSPC;
>  	} else if (rc) {
> diff --git a/arch/s390/crypto/phmac_s390.c 
> b/arch/s390/crypto/phmac_s390.c
> index 03ca33ffe6cc..da76c7beb184 100644
> --- a/arch/s390/crypto/phmac_s390.c
> +++ b/arch/s390/crypto/phmac_s390.c
> @@ -895,7 +895,7 @@ static int phmac_do_one_request(struct
> crypto_engine *engine, void *areq)
>  			 * tell scheduler to voluntarily give up the CPU here.
>  			 */
>  			pr_debug("rescheduling request\n");
> -			cond_resched();
> +			msleep(1);
>  			return -ENOSPC;
>  		} else if (rc) {
>  			hwh_advance(hwh, rc);
> @@ -916,7 +916,7 @@ static int phmac_do_one_request(struct
> crypto_engine *engine, void *areq)
>  			 * tell scheduler to voluntarily give up the CPU here.
>  			 */
>  			pr_debug("rescheduling request\n");
> -			cond_resched();
> +			msleep(1);
>  			return -ENOSPC;
>  		}
>  		break;

Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>