linux-kernel - Re: [PATCH] wlcore: consolidate kmalloc + memset 0 into kzalloc

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Message-ID: <CAGRGNgU+CA-jLAX=_qV27tfbyQ2cyjYo2NZOq3_7fFLc-VsCew@mail.gmail.com>
Date:	Tue, 22 Dec 2015 09:56:10 +1100
From:	Julian Calaby <julian.calaby@...il.com>
To:	Nicholas Mc Guire <hofrat@...dl.org>
Cc:	Kalle Valo <kvalo@...eaurora.org>, Eliad Peller <eliad@...ery.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Arik Nemtsov <arik@...ery.com>,
	Tony Lindgren <tony@...mide.com>,
	Luciano Coelho <luca@...lho.fi>,
	Eyal Reizer <eyalreizer@...il.com>,
	Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] wlcore: consolidate kmalloc + memset 0 into kzalloc

Hi,

On Tue, Dec 22, 2015 at 3:47 AM, Nicholas Mc Guire <hofrat@...dl.org> wrote:
> This is an API consolidation only. The use of kmalloc + memset to 0
> is equivalent to kzalloc.
>
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---
>
> Found by coccinelle script (relaxed version of
> scripts/coccinelle/api/alloc/kzalloc-simple.cocci)
>
> Patch was compile tested with: x86_64_defconfig +
> CONFIG_WL12XX=m (implies CONFIG_WLCORE=m)
>
> Patch is against linux-next (localversion-next is -next-20151221)
>
>  drivers/net/wireless/ti/wlcore/main.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ti/wlcore/main.c b/drivers/net/wireless/ti/wlcore/main.c
> index ec7f6af..dfc49bf 100644
> --- a/drivers/net/wireless/ti/wlcore/main.c
> +++ b/drivers/net/wireless/ti/wlcore/main.c
> @@ -838,7 +838,7 @@ static void wl12xx_read_fwlog_panic(struct wl1271 *wl)
>
>         wl1271_info("Reading FW panic log");
>
> -       block = kmalloc(wl->fw_mem_block_size, GFP_KERNEL);
> +       block = kzalloc(wl->fw_mem_block_size, GFP_KERNEL);
>         if (!block)
>                 return;
>
> @@ -885,7 +885,6 @@ static void wl12xx_read_fwlog_panic(struct wl1271 *wl)
>                         goto out;
>                 }
> -               memset(block, 0, wl->fw_mem_block_size);

I don't think you can't remove this line. It appears that the loop
this is part of resets block to be all zero, reads a chunk of data in,
then operates on it. I'm guessing that the code after the following
line expects that there isn't any data left over from previous runs
through the loop.

>                 ret = wlcore_read_hwaddr(wl, addr, block,
>                                         wl->fw_mem_block_size, false);
>
> --
> 2.1.4
>
> --
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-- 
Julian Calaby

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