linux-kernel - Re: [PATCH] powerpc/powernv/pci: Use kmalloc

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Date:   Thu, 25 Aug 2016 19:51:52 +0200
From:   walter harms <wharms@....de>
To:     unlisted-recipients:; (no To-header on input)
CC:     linuxppc-dev@...ts.ozlabs.org,
        Alexey Kardashevskiy <aik@...abs.ru>,
        Alistair Popple <alistair@...ple.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Gavin Shan <gwshan@...ux.vnet.ibm.com>,
        Ian Munsie <imunsie@....ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Wei Yang <weiyang@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Julia Lawall <julia.lawall@...6.fr>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH] powerpc/powernv/pci: Use kmalloc_array() in two functions



Am 24.08.2016 22:36, schrieb SF Markus Elfring:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Wed, 24 Aug 2016 22:26:37 +0200
> 
> A multiplication for the size determination of a memory allocation
> indicated that an array data structure should be processed.
> Thus reuse the corresponding function "kmalloc_array".
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  arch/powerpc/platforms/powernv/pci-ioda.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index fd9444f..2366552 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -1305,7 +1305,9 @@ static int pnv_pci_vf_assign_m64(struct pci_dev *pdev, u16 num_vfs)
>  	else
>  		m64_bars = 1;
>  
> -	pdn->m64_map = kmalloc(sizeof(*pdn->m64_map) * m64_bars, GFP_KERNEL);
> +	pdn->m64_map = kmalloc_array(m64_bars,
> +				     sizeof(*pdn->m64_map),
> +				     GFP_KERNEL);
>  	if (!pdn->m64_map)
>  		return -ENOMEM;
>  	/* Initialize the m64_map to IODA_INVALID_M64 */
> @@ -1572,8 +1574,9 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>  
>  		/* Allocating pe_num_map */
>  		if (pdn->m64_single_mode)
> -			pdn->pe_num_map = kmalloc(sizeof(*pdn->pe_num_map) * num_vfs,
> -					GFP_KERNEL);
> +			pdn->pe_num_map = kmalloc_array(num_vfs,
> +							sizeof(*pdn->pe_num_map),
> +							GFP_KERNEL);
>  		else
>  			pdn->pe_num_map = kmalloc(sizeof(*pdn->pe_num_map), GFP_KERNEL);
>  


what is the value of num_vfs in the !pdn->m64_single_mode case ?
otherwise someone could make it like:

if (!pdn->m64_single_mode)
   num_vfs=1;

pdn->pe_num_map = kmalloc_array(num_vfs, ....

so it looks a bit oversophisticated.

re,
 wh