[PATCH] RDMA/mana_ib: Add flex array to struct mana_cfg_rx_steer_req_v2

[Erick Archer]

The "struct mana_cfg_rx_steer_req_v2" uses a dynamically sized set of
trailing elements. Specifically, it uses a "mana_handle_t" array. So,
use the preferred way in the kernel declaring a flexible array [1].

Also, avoid the open-coded arithmetic in the memory allocator functions
[2] using the "struct_size" macro.

Moreover, use the "offsetof" helper to get the indirect table offset
instead of the "sizeof" operator and avoid the open-coded arithmetic in
pointers using the new flex member.

Now, it is also possible to use the "flex_array_size" helper to compute
the size of these trailing elements in the "memcpy" function.

Link: https://www.kernel.org/doc/html/next/process/deprecated.html#zero-length-and-one-element-arrays [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [2]
Signed-off-by: Erick Archer <erick.archer@xxxxxxxxxxx>
---
 drivers/infiniband/hw/mana/qp.c               | 8 ++++----
 drivers/net/ethernet/microsoft/mana/mana_en.c | 9 +++++----
 include/net/mana/mana.h                       | 1 +
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/hw/mana/qp.c b/drivers/infiniband/hw/mana/qp.c
index 6e7627745c95..c2a39db8ef92 100644
--- a/drivers/infiniband/hw/mana/qp.c
+++ b/drivers/infiniband/hw/mana/qp.c
@@ -22,8 +22,7 @@ static int mana_ib_cfg_vport_steering(struct mana_ib_dev *dev,
 
 	gc = mdev_to_gc(dev);
 
-	req_buf_size =
-		sizeof(*req) + sizeof(mana_handle_t) * MANA_INDIRECT_TABLE_SIZE;
+	req_buf_size = struct_size(req, indir_tab, MANA_INDIRECT_TABLE_SIZE);
 	req = kzalloc(req_buf_size, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
@@ -44,11 +43,12 @@ static int mana_ib_cfg_vport_steering(struct mana_ib_dev *dev,
 		req->rss_enable = true;
 
 	req->num_indir_entries = MANA_INDIRECT_TABLE_SIZE;
-	req->indir_tab_offset = sizeof(*req);
+	req->indir_tab_offset = offsetof(struct mana_cfg_rx_steer_req_v2,
+					 indir_tab);
 	req->update_indir_tab = true;
 	req->cqe_coalescing_enable = 1;
 
-	req_indir_tab = (mana_handle_t *)(req + 1);
+	req_indir_tab = req->indir_tab;
 	/* The ind table passed to the hardware must have
 	 * MANA_INDIRECT_TABLE_SIZE entries. Adjust the verb
 	 * ind_table to MANA_INDIRECT_TABLE_SIZE if required
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index 59287c6e6cee..04aa096c6cc4 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -1062,7 +1062,7 @@ static int mana_cfg_vport_steering(struct mana_port_context *apc,
 	u32 req_buf_size;
 	int err;
 
-	req_buf_size = sizeof(*req) + sizeof(mana_handle_t) * num_entries;
+	req_buf_size = struct_size(req, indir_tab, num_entries);
 	req = kzalloc(req_buf_size, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
@@ -1074,7 +1074,8 @@ static int mana_cfg_vport_steering(struct mana_port_context *apc,
 
 	req->vport = apc->port_handle;
 	req->num_indir_entries = num_entries;
-	req->indir_tab_offset = sizeof(*req);
+	req->indir_tab_offset = offsetof(struct mana_cfg_rx_steer_req_v2,
+					 indir_tab);
 	req->rx_enable = rx;
 	req->rss_enable = apc->rss_state;
 	req->update_default_rxobj = update_default_rxobj;
@@ -1087,9 +1088,9 @@ static int mana_cfg_vport_steering(struct mana_port_context *apc,
 		memcpy(&req->hashkey, apc->hashkey, MANA_HASH_KEY_SIZE);
 
 	if (update_tab) {
-		req_indir_tab = (mana_handle_t *)(req + 1);
+		req_indir_tab = req->indir_tab;
 		memcpy(req_indir_tab, apc->rxobj_table,
-		       req->num_indir_entries * sizeof(mana_handle_t));
+		       flex_array_size(req, indir_tab, req->num_indir_entries));
 	}
 
 	err = mana_send_request(apc->ac, req, req_buf_size, &resp,
diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
index 76147feb0d10..20ffcae29e1e 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -671,6 +671,7 @@ struct mana_cfg_rx_steer_req_v2 {
 	u8 hashkey[MANA_HASH_KEY_SIZE];
 	u8 cqe_coalescing_enable;
 	u8 reserved2[7];
+	mana_handle_t indir_tab[];
 }; /* HW DATA */
 
 struct mana_cfg_rx_steer_resp {
-- 
2.25.1