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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180410141721.GQ6014@localhost>
Date:   Tue, 10 Apr 2018 19:47:22 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Adam.Thomson.Opensource@...semi.com,
        Jia-Ju Bai <baijiaju1990@...il.com>, lgirdwood@...il.com,
        sathyanarayana.nujella@...el.com, broonie@...nel.org,
        perex@...ex.cz, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [alsa-devel] [PATCH] sound: soc: intel: bxt_da7219_max98357a:
 Replace GFP_ATOMIC with GFP_KERNEL in broxton_audio_probe

On Mon, Apr 09, 2018 at 09:39:06PM +0200, Takashi Iwai wrote:
> On Mon, 09 Apr 2018 20:57:43 +0200,
> Pierre-Louis Bossart wrote:
> > 
> > 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?
> 
> It must be sleepable context as it's a standard platform driver probe
> callback.
> 
> And now looking at grep output, only sound/soc/intel contains so many
> calls with GFP_ATOMIC.  I bet that almost all can be done with
> GFP_KERNEL, maybe only one or two in atom/sst would be conditionally
> with GFP_ATOMIC.

Yeah I don't see many cases which would warrant atomic context, I will review
them and fix these after merge window closes. Clearly machines have no
reason for that, and I guess most are copy-paste from 1st culprit

-- 
~Vinod