linux-kernel - [PATCH net-next] xprtrdma: Use struct

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Date:   Wed, 30 Jan 2019 18:46:22 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Jeff Layton <jlayton@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     linux-nfs@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH net-next] xprtrdma: Use struct_size() in kzalloc()

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 = kzalloc(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 = kzalloc(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>
---
 net/sunrpc/xprtrdma/verbs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 4994e75945b8..9e8cf7456840 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -811,8 +811,7 @@ static struct rpcrdma_sendctx *rpcrdma_sendctx_create(struct rpcrdma_ia *ia)
 {
 	struct rpcrdma_sendctx *sc;
 
-	sc = kzalloc(sizeof(*sc) +
-		     ia->ri_max_send_sges * sizeof(struct ib_sge),
+	sc = kzalloc(struct_size(sc, sc_sges, ia->ri_max_send_sges),
 		     GFP_KERNEL);
 	if (!sc)
 		return NULL;
-- 
2.20.1