[PATCH 3.16.y-ckt 014/168] srp-target: Retry when QP creation fails with ENOMEM

[Luis Henriques]

3.16.7-ckt3 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bvanassche at acm.org>

commit ab477c1ff5e0a744c072404bf7db51bfe1f05b6e upstream.

It is not guaranteed to that srp_sq_size is supported
by the HCA. So if we failed to create the QP with ENOMEM,
try with a smaller srp_sq_size. Keep it up until we hit
MIN_SRPT_SQ_SIZE, then fail the connection.

Reported-by: Mark Lehrer <lehrer at gmail.com>
Signed-off-by: Bart Van Assche <bvanassche at acm.org>
Signed-off-by: Sagi Grimberg <sagig at mellanox.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/infiniband/ulp/srpt/ib_srpt.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index fe09f2788b15..3ffaf4e6c671 100644
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -2091,6 +2091,7 @@ static int srpt_create_ch_ib(struct srpt_rdma_ch *ch)
 	if (!qp_init)
 		goto out;
 
+retry:
 	ch->cq = ib_create_cq(sdev->device, srpt_completion, NULL, ch,
 			      ch->rq_size + srp_sq_size, 0);
 	if (IS_ERR(ch->cq)) {
@@ -2114,6 +2115,13 @@ static int srpt_create_ch_ib(struct srpt_rdma_ch *ch)
 	ch->qp = ib_create_qp(sdev->pd, qp_init);
 	if (IS_ERR(ch->qp)) {
 		ret = PTR_ERR(ch->qp);
+		if (ret == -ENOMEM) {
+			srp_sq_size /= 2;
+			if (srp_sq_size >= MIN_SRPT_SQ_SIZE) {
+				ib_destroy_cq(ch->cq);
+				goto retry;
+			}
+		}
 		printk(KERN_ERR "failed to create_qp ret= %d\n", ret);
 		goto err_destroy_cq;
 	}
-- 
2.1.3