From: Ilya Dryomov <idryomov@gmail.com>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: "Yan, Zheng" <zyan@redhat.com>, Sage Weil <sage@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Ceph Development <ceph-devel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next] libceph, ceph: use struct_size() in kmalloc()
Date: Thu, 17 Jan 2019 15:17:33 +0100 [thread overview]
Message-ID: <CAOi1vP_yWH2mhquFObC6VnUzNTzc7PX7tqA3RP=ci71BMm-gqA@mail.gmail.com> (raw)
In-Reply-To: <20190115194153.GA9565@embeddedor>
On Tue, Jan 15, 2019 at 8:41 PM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
>
> 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@embeddedor.com>
> ---
> net/ceph/osdmap.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
> index 98c0ff3d6441..48a31dc9161c 100644
> --- a/net/ceph/osdmap.c
> +++ b/net/ceph/osdmap.c
> @@ -495,9 +495,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
> / sizeof(struct crush_rule_step))
> goto bad;
> #endif
> - r = c->rules[i] = kmalloc(sizeof(*r) +
> - yes*sizeof(struct crush_rule_step),
> - GFP_NOFS);
> + r = kmalloc(struct_size(r, steps, yes), GFP_NOFS);
> + c->rules[i] = r;
> if (r == NULL)
> goto badmem;
> dout(" rule %d is at %p\n", i, r);
Applied.
Thanks,
Ilya
next prev parent reply other threads:[~2019-01-17 14:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-15 19:41 [PATCH net-next] libceph, ceph: use struct_size() in kmalloc() Gustavo A. R. Silva
2019-01-17 14:17 ` Ilya Dryomov [this message]
2019-01-25 3:50 ` Gustavo A. R. Silva
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