linux-kernel - Re: [PATCH] ASoC: amd: Fix for Subsequent Playback issue.

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Message-ID: <20200121172657.GK4656@sirena.org.uk>
Date:   Tue, 21 Jan 2020 17:26:57 +0000
From:   Mark Brown <broonie@...nel.org>
To:     "RAVULAPATI, VISHNU VARDHAN RAO" 
        <Vishnuvardhanrao.Ravulapati@....com>
Cc:     "Deucher, Alexander" <Alexander.Deucher@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        "Mukunda, Vijendar" <Vijendar.Mukunda@....com>,
        Colin Ian King <colin.king@...onical.com>,
        YueHaibing <yuehaibing@...wei.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@...a-project.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: amd: Fix for Subsequent Playback issue.

On Tue, Jan 21, 2020 at 05:12:42PM +0000, RAVULAPATI, VISHNU VARDHAN RAO wrote:

Please fix your mailer to quote replies normally, it's hard to read your
mails.

> In what way is it part of the fix?  This at least needs some sort of
> explanation somewhere, the changelog at least if not the code.

> When we play subsequently we hear last played sound for moment.kfree clears the structure.

If the rtd is still being referenced after the kfree() you have a use
after free bug so there's a serious problem there and this change is
introducing a bug, you can only free things if they are not in use.  At
a bare minimum I need the changelog to clearly explain what the cause of
the clicks is and how the change fixes that.

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