nvme-tcp: Set SO_PRIORITY for all host sockets

Enable ability to associate all sockets related to NVMf TCP traffic
to a priority group that will perform optimized network processing for
this traffic class. Maintain initial default behavior of using priority
of zero.
Signed-off-by: Kiran Patil <kiran.patil@intel.com>
Signed-off-by: Mark Wunderlich <mark.wunderlich@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/tcp.c

@@ -20,6 +20,16 @@
 
 struct nvme_tcp_queue;
 
+/* Define the socket priority to use for connections were it is desirable
+ * that the NIC consider performing optimized packet processing or filtering.
+ * A non-zero value being sufficient to indicate general consideration of any
+ * possible optimization.  Making it a module param allows for alternative
+ * values that may be unique for some NIC implementations.
+ */
+static int so_priority;
+module_param(so_priority, int, 0644);
+MODULE_PARM_DESC(so_priority, "nvme tcp socket optimize priority");
+
 enum nvme_tcp_send_state {
 	NVME_TCP_SEND_CMD_PDU = 0,
 	NVME_TCP_SEND_H2C_PDU,
@@ -1309,6 +1319,17 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
 		goto err_sock;
 	}
 
+	if (so_priority > 0) {
+		ret = kernel_setsockopt(queue->sock, SOL_SOCKET, SO_PRIORITY,
+				(char *)&so_priority, sizeof(so_priority));
+		if (ret) {
+			dev_err(ctrl->ctrl.device,
+				"failed to set SO_PRIORITY sock opt, ret %d\n",
+				ret);
+			goto err_sock;
+		}
+	}
+
 	/* Set socket type of service */
 	if (nctrl->opts->tos >= 0) {
 		opt = nctrl->opts->tos;