Patch "IB/srpt: Limit the number of SG elements per work request" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

IB/srpt: Limit the number of SG elements per work request

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-srpt-limit-the-number-of-sg-elements-per-work-request.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bart Van Assche <[email protected]>
Date: Thu, 21 Jul 2016 13:03:47 -0700
Subject: IB/srpt: Limit the number of SG elements per work request

From: Bart Van Assche <[email protected]>

commit 30c6d8773de06878f920666d8c945f81cb2081b3 upstream.

Limit the number of SG elements per work request to what the HCA and the queue pair support.

---
 drivers/infiniband/ulp/srpt/ib_srpt.c |    3 ++-
 drivers/infiniband/ulp/srpt/ib_srpt.h |    6 +++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

@@ -1601,6 +1601,7 @@ static int srpt_create_ch_ib(struct srpt
 	struct ib_qp_init_attr *qp_init;
 	struct srpt_port *sport = ch->sport;
 	struct srpt_device *sdev = sport->sdev;
+	const struct ib_device_attr *attrs = &sdev->device->attrs;
 	u32 srp_sq_size = sport->port_attrib.srp_sq_size;
 	int ret;
 

@@ -1638,7 +1639,7 @@ retry:
 	 */
 	qp_init->cap.max_send_wr = srp_sq_size / 2;
 	qp_init->cap.max_rdma_ctxs = srp_sq_size / 2;
-	qp_init->cap.max_send_sge = SRPT_DEF_SG_PER_WQE;
+	qp_init->cap.max_send_sge = min(attrs->max_sge, SRPT_MAX_SG_PER_WQE);
 	qp_init->port_num = ch->sport->port;
 
 	ch->qp = ib_create_qp(sdev->pd, qp_init);

@@ -106,7 +106,11 @@ enum {
 	SRP_LOGIN_RSP_MULTICHAN_MAINTAINED = 0x2,
 
 	SRPT_DEF_SG_TABLESIZE = 128,
-	SRPT_DEF_SG_PER_WQE = 16,
+	/*
+	 * An experimentally determined value that avoids that QP creation
+	 * fails due to "swiotlb buffer is full" on systems using the swiotlb.
+	 */
+	SRPT_MAX_SG_PER_WQE = 16,
 
 	MIN_SRPT_SQ_SIZE = 16,
 	DEF_SRPT_SQ_SIZE = 4096,

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/dm-set-dmf_suspended-_before_-clearing-dmf_noflush_suspending.patch queue-4.7/ib-core-make-rdma_rw_ctx_init-initialize-all-used-fields.patch queue-4.7/ib-rdmavt-disable-by-default.patch queue-4.7/ib-srpt-limit-the-number-of-sg-elements-per-work-request.patch queue-4.7/ib-core-rdma-rw-api-do-not-exceed-qp-sge-send-limit.patch