ibmvscsis: Fix the incorrect req_lim_delta

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 98883f1b5415 ("ibmvscsis: Clear left-over abort_cmd pointers")

Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Reviewed-by: Michael Cyr <mikecyr@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # v4.8+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
index ee64241865e6..abf6026645dd 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;