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

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Message-ID: <CAFqt6zaYfbLqUDjcJ36TKMCXpy5_swjZQDj_75topDsMtfBRFA@mail.gmail.com>
Date:	Tue, 22 Dec 2015 12:36:43 +0530
From:	Souptick Joarder <jrdr.linux@...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@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] wlcore: consolidate kmalloc + memset 0 into kzalloc

On Mon, Dec 21, 2015 at 10:17 PM, 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);

Current code is reseting the block value to 0 in each iterations and
perform some operations.
But if you are using kzalloc as mentioned above it will memset 0 to
block pointer only once.
So both are not equivalent operations.

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