linux-kernel - Re: [alsa-devel] [PATCH] sound: soc: intel: bxt_da7219_max98357a: Replace GFP_ATOMIC with GFP_KERNEL in broxton_audio

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Date:   Mon, 9 Apr 2018 13:57:43 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Jia-Ju Bai <baijiaju1990@...il.com>, lgirdwood@...il.com,
        broonie@...nel.org, perex@...ex.cz, tiwai@...e.com,
        sathyanarayana.nujella@...el.com,
        Adam.Thomson.Opensource@...semi.com
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        Vinod Koul <vinod.koul@...el.com>
Subject: Re: [alsa-devel] [PATCH] sound: soc: intel: bxt_da7219_max98357a:
 Replace GFP_ATOMIC with GFP_KERNEL in broxton_audio_probe

On 4/9/18 5:46 AM, Jia-Ju Bai wrote:
> broxton_audio_probe() is never called in atomic context.
> This function is only set as ".probe" in "struct platform_driver".
> 
> Despite never getting called from atomic context,
> broxton_audio_probe() calls devm_kzalloc() with GFP_ATOMIC,
> which waits busily for allocation.
> GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
> to avoid busy waiting and improve the possibility of sucessful allocation.

[answering for the series]
Humm, this is interesting.
If indeed we can afford to sleep then the change should be done on ALL 
14 boards in sound/soc/intel/boards which follow the same code pattern.
If we cannot sleep then then none of these changes should be applied.
Liam and Vinod?

> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> ---
>   sound/soc/intel/boards/bxt_da7219_max98357a.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/soc/intel/boards/bxt_da7219_max98357a.c b/sound/soc/intel/boards/bxt_da7219_max98357a.c
> index ce35ec7..f4361b7 100644
> --- a/sound/soc/intel/boards/bxt_da7219_max98357a.c
> +++ b/sound/soc/intel/boards/bxt_da7219_max98357a.c
> @@ -585,7 +585,7 @@ static int broxton_audio_probe(struct platform_device *pdev)
>   {
>   	struct bxt_card_private *ctx;
>   
> -	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_ATOMIC);
> +	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
>   	if (!ctx)
>   		return -ENOMEM;
>   
>