On Thu, 2014-06-05 at 23:30 +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch changes ft_queue_data_in() to set SAM_STAT_TASK_SET_FULL
> status upon a lport->tt.seq_send() failure, where it will now stop
> sending subsequent DataIN, and immediately attempt to send the
> response with exception status.
>
> Sending a response with SAM_STAT_TASK_SET_FULL status is useful in
> order to signal the initiator that it should try to reduce it's
> current queue_depth, to lower the number of outstanding I/Os on
> the wire.
>
> Also, add a check to skip sending DataIN if TASK_SET_FULL status
> has already been set due to a response lport->tt.seq_send()
> failure, that has asked target-core to requeue a response.
>
> Reported-by: Vasu Dev <vasu.dev@xxxxxxxxxxxxxxx>
> Cc: Vasu Dev <vasu.dev@xxxxxxxxxxxxxxx>
> Cc: Jun Wu <jwu@xxxxxxxxxxxx>
> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> drivers/target/tcm_fc/tfc_io.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/target/tcm_fc/tfc_io.c b/drivers/target/tcm_fc/tfc_io.c
> index e415af3..140659f 100644
> --- a/drivers/target/tcm_fc/tfc_io.c
> +++ b/drivers/target/tcm_fc/tfc_io.c
> @@ -82,6 +82,10 @@ int ft_queue_data_in(struct se_cmd *se_cmd)
>
> if (cmd->aborted)
> return 0;
> +
> + if (se_cmd->scsi_status == SAM_STAT_TASK_SET_FULL)
> + goto queue_status;
> +
> ep = fc_seq_exch(cmd->seq);
> lport = ep->lp;
> cmd->seq = lport->tt.seq_start_next(cmd->seq);
> @@ -178,14 +182,22 @@ int ft_queue_data_in(struct se_cmd *se_cmd)
> FC_TYPE_FCP, f_ctl, fh_off);
> error = lport->tt.seq_send(lport, seq, fp);
> if (error) {
> - /* XXX For now, initiator will retry */
> pr_err_ratelimited("%s: Failed to send frame %p, "
> "xid <0x%x>, remaining %zu, "
> "lso_max <0x%x>\n",
> __func__, fp, ep->xid,
> remaining, lport->lso_max);
> + /*
> + * Generate a TASK_SET_FULL status to notify the
> + * initiator to reduce it's queue_depth, ignoring
> + * the rest of the data-in and immediately attempt
> + * to send the response.
> + */
I see above added check will drop rest of the frames but cannot find
notifying to initiator with the TASK_SET_FULL status as in comments
above, may be just the comment needs update otherwise code changes are
fine.
> + se_cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
> + break;
> }
> }
> +queue_status:
> return ft_queue_status(se_cmd);
> }
>
Reviewed-by: Vasu Dev <vasu.dev@xxxxxxxxx>
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