linux-kernel - [PATCH][next] Bluetooth: a2mp: Use struct

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Message-ID: <20190208002817.GA15338@embeddedor>
Date:   Thu, 7 Feb 2019 18:28:17 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH][next] Bluetooth: a2mp: Use struct_size() helper

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = alloc(size, GFP_KERNEL)

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

size = struct_size(instance, entry, count);
instance = alloc(size, GFP_KERNEL)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 net/bluetooth/a2mp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/a2mp.c b/net/bluetooth/a2mp.c
index 58fc6333d412..5f918ea18b5a 100644
--- a/net/bluetooth/a2mp.c
+++ b/net/bluetooth/a2mp.c
@@ -174,7 +174,7 @@ static int a2mp_discover_req(struct amp_mgr *mgr, struct sk_buff *skb,
 			num_ctrl++;
 	}
 
-	len = num_ctrl * sizeof(struct a2mp_cl) + sizeof(*rsp);
+	len = struct_size(rsp, cl, num_ctrl);
 	rsp = kmalloc(len, GFP_ATOMIC);
 	if (!rsp) {
 		read_unlock(&hci_dev_list_lock);
-- 
2.20.1