Commit 75dbf2d3 authored May 10, 2017 by Bryant G. Ly Committed by Nicholas Bellinger May 15, 2017

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 25e78531 ("ibmvscsis: Do not send aborted task response")
commit 98883f1b ("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>

parent 98883f1b

drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c

+20 −4

Original line number	Diff line number	Diff line
		@@ -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;

		@@ -2965,9 +2984,6 @@ 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->tag = cmd->rsp.tag;
		rsp->flags = 0;