linux-kernel - [PATCH net-next] tulip: eeprom: use struct

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Message-ID: <20190131003355.GA27627@embeddedor>
Date:   Wed, 30 Jan 2019 18:33:55 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-parisc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH net-next] tulip: eeprom: use struct_size() in kmalloc()

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[];
};

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

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

instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/net/ethernet/dec/tulip/eeprom.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/dec/tulip/eeprom.c b/drivers/net/ethernet/dec/tulip/eeprom.c
index 1812f4916917..ba0a69b363f8 100644
--- a/drivers/net/ethernet/dec/tulip/eeprom.c
+++ b/drivers/net/ethernet/dec/tulip/eeprom.c
@@ -224,9 +224,7 @@ void tulip_parse_eeprom(struct net_device *dev)
 		        return;
 		}
 
-		mtable = kmalloc(sizeof(struct mediatable) +
-				 count * sizeof(struct medialeaf),
-				 GFP_KERNEL);
+		mtable = kmalloc(struct_size(mtable, mleaf, count), GFP_KERNEL);
 		if (mtable == NULL)
 			return;				/* Horrible, impossible failure. */
 		last_mediatable = tp->mtable = mtable;
-- 
2.20.1