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Sun, 28 Jan 2018 17:58:59 -0500 Received: from mail-bn3nam01on0128.outbound.protection.outlook.com ([104.47.33.128]:55858 "EHLO NAM01-BN3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753578AbeA1W1z (ORCPT ); Sun, 28 Jan 2018 17:27:55 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Jiada Wang , Mark Brown , "Sasha Levin" Subject: [PATCH AUTOSEL for 4.14 089/100] ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update Thread-Topic: [PATCH AUTOSEL for 4.14 089/100] ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update Thread-Index: AQHTmIcbS8xfc2Ixek2sO6w+k4RxRA== Date: Sun, 28 Jan 2018 22:26:57 +0000 Message-ID: <20180128222547.7398-89-alexander.levin@microsoft.com> References: <20180128222547.7398-1-alexander.levin@microsoft.com> In-Reply-To: <20180128222547.7398-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;MW2PR2101MB1018;7:zwhuYCEsKcyqpk0sbDOhr76EYxMJCNqEWVyGDb24ejwHgI9bP1pEzB+JsWs3Z7tsnjG9JqlgR6ZU+TRDbALjXBtA4e59bizdiFPF6vh5YKjUmHS4zdcdkglMt3FjSdLA2eflibShPVv+aqyzO0vbxjrYcbO7ywSRha6hyBpqoSvv9hVSEaJeVryew1udjpWzyrxkjC695s2CLCqJA60P7jbeRIefxsfTeH+OPVvA5+jzi9dDmkaft0lo715i1etN x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: fcfba11a-baed-4221-5da4-08d5669e5aab x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(4627221)(201703031133081)(201702281549075)(48565401081)(5600026)(4604075)(3008032)(2017052603307)(7193020);SRVR:MW2PR2101MB1018; 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x-microsoft-antispam-message-info: MmSd9S+CbMNWpQRt3EpocDd5lb2xeWv7oJq1lngyYmgQHqHOSE19JHMXyNhT52XRAVXvsLo3WOvoL2pRx3EwqQ== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: fcfba11a-baed-4221-5da4-08d5669e5aab X-MS-Exchange-CrossTenant-originalarrivaltime: 28 Jan 2018 22:26:57.5678 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW2PR2101MB1018 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Jiada Wang [ Upstream commit 33f801366bdf3f8b67dfe325b84f4051a090d01e ] Currently there is race condition between set of byte_pos and wrap it around when new buffer starts. If .pointer is called in-between it will result in inconsistent pointer position be returned from .pointer callback. This patch increments buffer pointer atomically to avoid this issue. Signed-off-by: Jiada Wang Reviewed-by: Takashi Sakamoto Acked-by: Kuninori Morimoto Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- sound/soc/sh/rcar/ssi.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/sound/soc/sh/rcar/ssi.c b/sound/soc/sh/rcar/ssi.c index 2aef7c00cca1..f0fb85fda42d 100644 --- a/sound/soc/sh/rcar/ssi.c +++ b/sound/soc/sh/rcar/ssi.c @@ -449,25 +449,29 @@ static bool rsnd_ssi_pointer_update(struct rsnd_mod *= mod, int byte) { struct rsnd_ssi *ssi =3D rsnd_mod_to_ssi(mod); + bool ret =3D false; + int byte_pos; =20 - ssi->byte_pos +=3D byte; + byte_pos =3D ssi->byte_pos + byte; =20 - if (ssi->byte_pos >=3D ssi->next_period_byte) { + if (byte_pos >=3D ssi->next_period_byte) { struct snd_pcm_runtime *runtime =3D rsnd_io_to_runtime(io); =20 ssi->period_pos++; ssi->next_period_byte +=3D ssi->byte_per_period; =20 if (ssi->period_pos >=3D runtime->periods) { - ssi->byte_pos =3D 0; + byte_pos =3D 0; ssi->period_pos =3D 0; ssi->next_period_byte =3D ssi->byte_per_period; } =20 - return true; + ret =3D true; } =20 - return false; + WRITE_ONCE(ssi->byte_pos, byte_pos); + + return ret; } =20 /* @@ -838,7 +842,7 @@ static int rsnd_ssi_pointer(struct rsnd_mod *mod, struct rsnd_ssi *ssi =3D rsnd_mod_to_ssi(mod); struct snd_pcm_runtime *runtime =3D rsnd_io_to_runtime(io); =20 - *pointer =3D bytes_to_frames(runtime, ssi->byte_pos); + *pointer =3D bytes_to_frames(runtime, READ_ONCE(ssi->byte_pos)); =20 return 0; } --=20 2.11.0