linux-kernel - RE: [Intel-wired-lan] [PATCH][next] i40e/i40e_virtchnl_pf: Use struct

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Date:   Thu, 13 Jun 2019 21:33:33 +0000
From:   "Bowers, AndrewX" <andrewx.bowers@...el.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [Intel-wired-lan] [PATCH][next] i40e/i40e_virtchnl_pf: Use
 struct_size() in kzalloc()

> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@...osl.org] On
> Behalf Of Gustavo A. R. Silva
> Sent: Wednesday, June 5, 2019 8:41 AM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>; David S. Miller
> <davem@...emloft.net>
> Cc: netdev@...r.kernel.org; intel-wired-lan@...ts.osuosl.org; linux-
> kernel@...r.kernel.org
> Subject: [Intel-wired-lan] [PATCH][next] i40e/i40e_virtchnl_pf: 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 virtchnl_iwarp_qvlist_info {
> 	...
>         struct virtchnl_iwarp_qv_info qv_info[1]; };
> 
> size = sizeof(struct virtchnl_iwarp_qvlist_info) + (sizeof(struct
> virtchnl_iwarp_qv_info) * count; instance = kzalloc(size, GFP_KERNEL);
> 
> and
> 
> struct virtchnl_vf_resource {
> 	...
>         struct virtchnl_vsi_resource vsi_res[1]; };
> 
> size = sizeof(struct virtchnl_vf_resource) + sizeof(struct
> virtchnl_vsi_resource) * count; instance = kzalloc(size, 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, qv_info, count), GFP_KERNEL);
> 
> and
> 
> instance = kzalloc(struct_size(instance, vsi_res, count), GFP_KERNEL);
> 
> Notice that, in the first case above, variable size is not necessary, hence it is
> removed.
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
>  .../net/ethernet/intel/i40e/i40e_virtchnl_pf.c    | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)

Tested-by: Andrew Bowers <andrewx.bowers@...el.com>