linux-kernel - Re: [PATCH 2/3] sound: enable interrupt after dma buffer initialization

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Message-ID: <s5hbm9436va.wl-tiwai@suse.de>
Date:   Tue, 11 Sep 2018 08:06:49 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     "Yu Zhao" <yuzhao@...gle.com>
Cc:     "Mark Brown" <broonie@...nel.org>, <alsa-devel@...a-project.org>,
        "Rakesh Ughreja" <rakesh.a.ughreja@...el.com>,
        "Vinod Koul" <vkoul@...nel.org>,
        "Jaroslav Kysela" <perex@...ex.cz>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] sound: enable interrupt after dma buffer initialization

On Mon, 10 Sep 2018 23:21:50 +0200,
Yu Zhao wrote:
> 
> In snd_hdac_bus_init_chip(), we enable interrupt before
> snd_hdac_bus_init_cmd_io() initializing dma buffers. If irq has
> been acquired and irq handler uses the dma buffer, kernel may crash
> when interrupt comes in.
> 
> Fix the problem by postponing enabling irq after dma buffer
> initialization. And warn once on null dma buffer pointer during the
> initialization.
> 
> Signed-off-by: Yu Zhao <yuzhao@...gle.com>

Looks good to me.

Reviewed-by: Takashi Iwai <tiwai@...e.de>


BTW, the reason why this hasn't been hit on the legacy HD-audio driver
is that we allocate usually with MSI, so the irq is isolated.

Any reason that Intel SKL driver doesn't use MST?


thanks,

Takashi