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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Shuah Khan <shuah.khan@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	konrad.wilk@oracle.com, rob@landley.net, joerg.roedel@amd.com,
	shuahkhan@gmail.com, devel@linuxdriverproject.org,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH] Documentation DMA-API-HOWTO.txt Add dma mapping error check usage examples
Date: Thu, 18 Oct 2012 12:47:15 +0300	[thread overview]
Message-ID: <20121018094715.GC5685@mwanda> (raw)
In-Reply-To: <1350230064.4069.1.camel@lorien2>

On Sun, Oct 14, 2012 at 09:54:24AM -0600, Shuah Khan wrote:
> diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
> index a0b6250..cf1adb4 100644
> --- a/Documentation/DMA-API-HOWTO.txt
> +++ b/Documentation/DMA-API-HOWTO.txt
> @@ -468,11 +468,46 @@ To map a single region, you do:
>  	size_t size = buffer->len;
>  
>  	dma_handle = dma_map_single(dev, addr, size, direction);
> +	if (unlikely(dma_mapping_error(dma_handle))) {

Don't encourage people to put unlikely() and likely() into their
driver code.  It should only be used after benchmarking both with
and without.  I can't imagine how it would make a measurable
difference here.

regards,
dan carpenter



  reply	other threads:[~2012-10-18  9:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-14 15:54 [PATCH] Documentation DMA-API-HOWTO.txt Add dma mapping error check usage examples Shuah Khan
2012-10-18  9:47 ` Dan Carpenter [this message]
2012-10-18 10:13   ` Michael Kerrisk (man-pages)
2012-10-18 14:30     ` Shuah Khan
2012-10-18 20:00     ` [PATCH v2] " Shuah Khan
2012-10-18 21:32       ` Jesper Juhl
2012-10-19 16:57       ` Konrad Rzeszutek Wilk
2012-10-24 15:09       ` Joerg Roedel

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