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Subject: Re: [PATCH net-next] xprtrdma: Use struct_size() in kzalloc()
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <20190131004622.GA30261@embeddedor>
Date:   Thu, 31 Jan 2019 09:11:24 -0500
Cc:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Bruce Fields <bfields@fieldses.org>,
        Jeff Layton <jlayton@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <07CB966E-A946-4956-8480-C0FC13E13E4E@oracle.com>
References: <20190131004622.GA30261@embeddedor>
To:     "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Sender: linux-nfs-owner@vger.kernel.org
Precedence: bulk


> On Jan 30, 2019, at 7:46 PM, Gustavo A. R. Silva =
<gustavo@embeddedor.com> wrote:
>=20
> 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:
>=20
> struct foo {
>    int stuff;
>    struct boo entry[];
> };
>=20
> instance =3D kzalloc(sizeof(struct foo) + count * sizeof(struct boo), =
GFP_KERNEL);
>=20
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>=20
> instance =3D kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
>=20
> This code was detected with the help of Coccinelle.
>=20
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>


> ---
> net/sunrpc/xprtrdma/verbs.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>=20
> 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;
>=20
> -	sc =3D kzalloc(sizeof(*sc) +
> -		     ia->ri_max_send_sges * sizeof(struct ib_sge),
> +	sc =3D kzalloc(struct_size(sc, sc_sges, ia->ri_max_send_sges),
> 		     GFP_KERNEL);
> 	if (!sc)
> 		return NULL;
> --=20
> 2.20.1
>=20

--
Chuck Lever