[PATCH v2 2/3] firewire: use struct_size over open coded arithmetic

[Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>]

From: "Minghao Chi (CGEL ZTE)" <chi.minghao@xxxxxxxxxx>

Replace zero-length array with flexible-array member and make use
of the struct_size() helper in kmalloc(). For example:

struct fw_request {
    ...
    u32 data[];
}

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

(Revised by Takashi Sakamoto to fix the value of third argument.)

Signed-off-by: Minghao Chi (CGEL ZTE) <chi.minghao@xxxxxxxxxx>
Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
---
 drivers/firewire/core-transaction.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index af498d767702..4604a9d97fd1 100644
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -779,7 +779,8 @@ static struct fw_request *allocate_request(struct fw_card *card,
 		return NULL;
 	}
 
-	request = kmalloc(sizeof(*request) + length, GFP_ATOMIC);
+	request = kmalloc(struct_size(request, data, length / sizeof(request->data[0])),
+			  GFP_ATOMIC);
 	if (request == NULL)
 		return NULL;
 
-- 
2.34.1