[PATCH 1/1] cr: s390: set return value for self-checkpoint

[PATCH 1/1] cr: s390: set return value for self-checkpoint

[Serge E. Hallyn]

If doing a self-checkpoint, then optimistically store 0 as the
syscall return value to indicate success.

This was being done for x86, but not yet being done for s390.

Signed-off-by: Serge E. Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 arch/s390/mm/checkpoint.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/arch/s390/mm/checkpoint.c b/arch/s390/mm/checkpoint.c
index a4a5da9..40dd417 100644
--- a/arch/s390/mm/checkpoint.c
+++ b/arch/s390/mm/checkpoint.c
@@ -54,6 +54,17 @@ static void s390_copy_regs(int op, struct ckpt_hdr_cpu *h,
 	CKPT_COPY(op, h->instruction_fetch, thr->per_info.instruction_fetch);
 
 	CKPT_COPY_ARRAY(op, h->gprs, regs->gprs, NUM_GPRS);
+	/*
+	 * for checkpoint in process context (from within a container),
+	 * the actual syscall is taking place at this very moment; so
+	 * we (optimistically) subtitute the future return value (0) of
+	 * this syscall into the orig_eax, so that upon restart it will
+	 * succeed (or it will endlessly retry checkpoint...)
+	 */
+	if (op == CKPT_CPT && t==current) {
+		BUG_ON(h->gprs[2] < 0);
+		h->gprs[2] = 0;
+	}
 	CKPT_COPY_ARRAY(op, h->fprs, thr->fp_regs.fprs, NUM_FPRS);
 	CKPT_COPY_ARRAY(op, h->acrs, thr->acrs, NUM_ACRS);
 	CKPT_COPY_ARRAY(op, h->per_control_regs,
-- 
1.6.1

Re: [PATCH 1/1] cr: s390: set return value for self-checkpoint

[Oren Laadan]

Got it, thanks.

Serge E. Hallyn wrote:
> If doing a self-checkpoint, then optimistically store 0 as the
> syscall return value to indicate success.
> 
> This was being done for x86, but not yet being done for s390.
> 
> Signed-off-by: Serge E. Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> ---
>  arch/s390/mm/checkpoint.c |   11 +++++++++++
>  1 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/s390/mm/checkpoint.c b/arch/s390/mm/checkpoint.c
> index a4a5da9..40dd417 100644
> --- a/arch/s390/mm/checkpoint.c
> +++ b/arch/s390/mm/checkpoint.c
> @@ -54,6 +54,17 @@ static void s390_copy_regs(int op, struct ckpt_hdr_cpu *h,
>  	CKPT_COPY(op, h->instruction_fetch, thr->per_info.instruction_fetch);
>  
>  	CKPT_COPY_ARRAY(op, h->gprs, regs->gprs, NUM_GPRS);
> +	/*
> +	 * for checkpoint in process context (from within a container),
> +	 * the actual syscall is taking place at this very moment; so
> +	 * we (optimistically) subtitute the future return value (0) of
> +	 * this syscall into the orig_eax, so that upon restart it will
> +	 * succeed (or it will endlessly retry checkpoint...)
> +	 */
> +	if (op == CKPT_CPT && t==current) {
> +		BUG_ON(h->gprs[2] < 0);
> +		h->gprs[2] = 0;
> +	}
>  	CKPT_COPY_ARRAY(op, h->fprs, thr->fp_regs.fprs, NUM_FPRS);
>  	CKPT_COPY_ARRAY(op, h->acrs, thr->acrs, NUM_ACRS);
>  	CKPT_COPY_ARRAY(op, h->per_control_regs,