[PATCH 4.4 55/97] IB/srp: Fix completion vector assignment algorithm

[Greg Kroah-Hartman]

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

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

From: Bart Van Assche <bart.vanassche@xxxxxxx>

commit 3a148896b24adf8688dc0c59af54531931677a40 upstream.

Ensure that cv_end is equal to ibdev->num_comp_vectors for the
NUMA node with the highest index. This patch improves spreading
of RDMA channels over completion vectors and thereby improves
performance, especially on systems with only a single NUMA node.
This patch drops support for the comp_vector login parameter by
ignoring the value of that parameter since I have not found a
good way to combine support for that parameter and automatic
spreading of RDMA channels over completion vectors.

Fixes: d92c0da71a35 ("IB/srp: Add multichannel support")
Reported-by: Alexander Schmid <alex@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Cc: Alexander Schmid <alex@xxxxxxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/ulp/srp/ib_srp.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -3311,12 +3311,10 @@ static ssize_t srp_create_target(struct
 				      num_online_nodes());
 		const int ch_end = ((node_idx + 1) * target->ch_count /
 				    num_online_nodes());
-		const int cv_start = (node_idx * ibdev->num_comp_vectors /
-				      num_online_nodes() + target->comp_vector)
-				     % ibdev->num_comp_vectors;
-		const int cv_end = ((node_idx + 1) * ibdev->num_comp_vectors /
-				    num_online_nodes() + target->comp_vector)
-				   % ibdev->num_comp_vectors;
+		const int cv_start = node_idx * ibdev->num_comp_vectors /
+				     num_online_nodes();
+		const int cv_end = (node_idx + 1) * ibdev->num_comp_vectors /
+				   num_online_nodes();
 		int cpu_idx = 0;
 
 		for_each_online_cpu(cpu) {