[PATCH v12 11/26] nvme-tcp: Add modparam to control the ULP offload enablement

[Aurelien Aptel]

Add ulp_offload module parameter to the nvme-tcp module to control
ULP offload at the NVMe-TCP layer.

Turn ULP offload off be default, regardless of the NIC driver support.

Overall, in order to enable ULP offload:
- nvme-tcp ulp_offload modparam must be set to 1
- netdev->ulp_ddp_caps.active must have ULP_DDP_C_NVME_TCP and/or
  ULP_DDP_C_NVME_TCP_DDGST_RX capabilities flag set.

Signed-off-by: Yoray Zack <yorayz at nvidia.com>
Signed-off-by: Shai Malin <smalin at nvidia.com>
Signed-off-by: Aurelien Aptel <aaptel at nvidia.com>
---
 drivers/nvme/host/tcp.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index e68e5da3df76..e560bdf3a023 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -49,6 +49,16 @@ MODULE_PARM_DESC(tls_handshake_timeout,
 		 "nvme TLS handshake timeout in seconds (default 10)");
 #endif
 
+#ifdef CONFIG_ULP_DDP
+/* NVMeTCP direct data placement and data digest offload will not
+ * happen if this parameter false (default), regardless of what the
+ * underlying netdev capabilities are.
+ */
+static bool ulp_offload;
+module_param(ulp_offload, bool, 0644);
+MODULE_PARM_DESC(ulp_offload, "Enable or disable NVMeTCP ULP support");
+#endif
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 /* lockdep can detect a circular dependency of the form
  *   sk_lock -> mmap_lock (page fault) -> fs locks -> sk_lock
@@ -350,7 +360,7 @@ static bool nvme_tcp_ddp_query_limits(struct net_device *netdev,
 static inline bool is_netdev_ulp_offload_active(struct net_device *netdev,
 						struct nvme_tcp_queue *queue)
 {
-	if (!netdev || !queue)
+	if (!ulp_offload || !netdev || !queue)
 		return false;
 
 	/* If we cannot query the netdev limitations, do not offload */
-- 
2.34.1