[3.16.y-ckt stable] Patch "IB/srp: Fix possible send queue overflow" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    IB/srp: Fix possible send queue overflow

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt23.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From bb087aec2f2ccb8f4ba97a00306b822f249fd27c Mon Sep 17 00:00:00 2001
From: Sagi Grimberg <sagig at mellanox.com>
Date: Tue, 1 Dec 2015 10:18:03 -0800
Subject: IB/srp: Fix possible send queue overflow

commit 09c0c0bea500a9ad362589990ee316c9b2482f44 upstream.

When using work request based memory registration (fast_reg)
we must reserve SQ entries for registration and invalidation
in addition to send operations. Each IO consumes 3 SQ entries
(registration, send, invalidation) so we need to allocate 3x
larger send-queue instead of 2x.

Signed-off-by: Sagi Grimberg <sagig at mellanox.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Signed-off-by: Doug Ledford <dledford at redhat.com>
[ luis: backported to 3.16:
  - change function srp_create_target_ib() instead of srp_create_ch_ib()
  - adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 767000811cf9..36876960f97e 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -451,7 +451,7 @@ static int srp_create_target_ib(struct srp_target_port *target)
 	struct ib_qp *qp;
 	struct ib_fmr_pool *fmr_pool = NULL;
 	struct srp_fr_pool *fr_pool = NULL;
-	const int m = 1 + dev->use_fast_reg;
+	const int m = dev->use_fast_reg ? 3 : 1;
 	int ret;

 	init_attr = kzalloc(sizeof *init_attr, GFP_KERNEL);