On Wed, 2017-05-10 at 14:35 -0500, Bryant G. Ly wrote:
> The current code is not correctly calculating the req_lim_delta.
>
> We want to make sure vscsi->credit is always incremented when
> we do not send a response for the scsi op. Thus for the case where
> there is a successfully aborted task we need to make sure the
> vscsi->credit is incremented.
>
> v2 - Moves the original location of the vscsi->credit increment
> to a better spot. Since if we increment credit, the next command
> we send back will have increased req_lim_delta. But we probably
> shouldn't be doing that until the aborted cmd is actually released.
> Otherwise the client will think that it can send a new command, and
> we could find ourselves short of command elements. Not likely, but could
> happen.
>
> This patch depends on both:
> commit 25e78531268e ("ibmvscsis: Do not send aborted task response")
> commit 38b2788edbd6 ("ibmvscsis: Clear left-over abort_cmd pointers")
>
> Signed-off-by: Bryant G. Ly <bryantly@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Michael Cyr <mikecyr@xxxxxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.8+
> ---
> drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> index ee64241..abf6026 100644
> --- a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> +++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> @@ -1791,6 +1791,25 @@ static void ibmvscsis_send_messages(struct scsi_info *vscsi)
> list_del(&cmd->list);
> ibmvscsis_free_cmd_resources(vscsi,
> cmd);
> + /*
> + * With a successfully aborted op
> + * through LIO we want to increment the
> + * the vscsi credit so that when we dont
> + * send a rsp to the original scsi abort
> + * op (h_send_crq), but the tm rsp to
> + * the abort is sent, the credit is
> + * correctly sent with the abort tm rsp.
> + * We would need 1 for the abort tm rsp
> + * and 1 credit for the aborted scsi op.
> + * Thus we need to increment here.
> + * Also we want to increment the credit
> + * here because we want to make sure
> + * cmd is actually released first
> + * otherwise the client will think it
> + * it can send a new cmd, and we could
> + * find ourselves short of cmd elements.
> + */
> + vscsi->credit += 1;
> } else {
> iue = cmd->iue;
>
> @@ -2965,10 +2984,7 @@ static long srp_build_response(struct scsi_info *vscsi,
>
> rsp->opcode = SRP_RSP;
>
> - if (vscsi->credit > 0 && vscsi->state == SRP_PROCESSING)
> - rsp->req_lim_delta = cpu_to_be32(vscsi->credit);
> - else
> - rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
> + rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
> rsp->tag = cmd->rsp.tag;
> rsp->flags = 0;
>
Thanks Bryant. Will apply post -rc1.
