[PATCH 4.11 065/115] ibmvscsis: Fix the incorrect req_lim_delta

Greg Kroah-Hartman
2017-06-05T16:31:55Z

From: Bryant G. Ly <bryantly@linux.vnet.ibm.com>

commit 75dbf2d36f6b122ad3c1070fe4bf95f71bbff321 upstream.

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>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)

--- 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(stru
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 sc

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;