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mx.google.com; dkim=pass header.i=@microsoft.com header.s=selector1 header.b=m9nHar1a; spf=pass (google.com: domain of alexander.levin@microsoft.com designates 104.47.40.106 as permitted sender) smtp.mailfrom=Alexander.Levin@microsoft.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=microsoft.com Authentication-Results: mx.google.com; dkim=pass header.i=@microsoft.com header.s=selector1 header.b=m9nHar1a; spf=pass (google.com: domain of alexander.levin@microsoft.com designates 104.47.40.106 as permitted sender) smtp.mailfrom=Alexander.Levin@microsoft.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=microsoft.com From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Geert Uytterhoeven , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL for 4.9 072/281] serial: sh-sci: Fix race condition causing garbage during shutdown Thread-Topic: [PATCH AUTOSEL for 4.9 072/281] serial: sh-sci: Fix race condition causing garbage during shutdown Thread-Index: AQHTv5s5L95EgF/EmkWj/pdNOyX03w== Date: Mon, 19 Mar 2018 15:59:13 +0000 Message-ID: <20180319155742.13731-72-alexander.levin@microsoft.com> References: <20180319155742.13731-1-alexander.levin@microsoft.com> In-Reply-To: <20180319155742.13731-1-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;DM5PR2101MB0869;7:ao/EriwivWZdST+hIEbJf+zvn8Gn/s8ffnSIsLuCgXFr8WVETdpruOwAS3KBsFHywXxitDWWOSeDVtk1bx6B9GMUbvzG9MNRYglG/+pn/r1GHmxEYjqgd238qL/SvtOzW3jpdmALaNHnkbb16EBjO231N2rVn5zT5auMq4fohm7PSRQrfTP77GIow/XohJFzR+D1RQy+G4xQAs1WcLxFQ/8BPvmGJ/Vw6HLLUR3IlnrgJuny7SwF3AYFU3wDz6aa;20:fxhBo+ELnvtu4jAEFWC96D03WNCWBjazZyUic3JFjxmiIRhTaO4owuRMnbcitL/EH2jExlCw4JrqeGOqDhl+TgILPiKezACrDR+n/0Gxmir5exrW6By0gnMT9DRjwkHXuwcIZd6DcfDmscQ6euISqveYcyL3uXKMiBG7FsACCgQ= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 1511a02e-3f10-4743-41df-08d58db2781e x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB0869; 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x-microsoft-antispam-message-info: XgwPjJXYFzI7jSiEQRf3L02rKeRjUbS/uMQlVxVMgAPgO/yV+nZ8EXNsA0aN9GB7VegVJmUgBahGAfhL452oQwIMoWDBjt+FMOqYREgp0+TiWnIX3FR8IHMS2bxs4x44y8vFsGemj1y7nvXPvvN0joIIP42sKg1KxWAmJWb4+268hDLN4M4YdkB4OHjs2CwlHzif039mshzGUKnjlnMFqLUqDh9/Kr5/sgjM1kxuyKpR0YbfWbXAaD/4aAAfD31kLYQCirpbq48Z4d5n/fGjt0oszzcGSb4kuuOyEkawEvCLHV8ZUVs/Kbw7MaC4Wkce4ujc9LiZ4CpwVrpqAVWOGA== 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: 1511a02e-3f10-4743-41df-08d58db2781e X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Mar 2018 15:59:13.8902 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB0869 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595382381074210323?= X-GMAIL-MSGID: =?utf-8?q?1595382381074210323?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Geert Uytterhoeven [ Upstream commit 1cf4a7efdc71cab84c42cfea7200608711ea954f ] If DMA is enabled and used, a burst of old data may be seen on the serial console during "poweroff" or "reboot". uart_flush_buffer() clears the circular buffer, but sci_port.tx_dma_len is not reset. This leads to a circular buffer overflow, dumping (UART_XMIT_SIZE - sci_port.tx_dma_len) bytes. To fix this, add a .flush_buffer() callback that resets sci_port.tx_dma_len. Inspired by commit 31ca2c63fdc0aee7 ("tty/serial: atmel: fix race condition (TX+DMA)"). Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/sh-sci.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 15eaea53b3df..6c6ad902e6b8 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1543,7 +1543,16 @@ static void sci_free_dma(struct uart_port *port) if (s->chan_rx) sci_rx_dma_release(s, false); } -#else + +static void sci_flush_buffer(struct uart_port *port) +{ + /* + * In uart_flush_buffer(), the xmit circular buffer has just been + * cleared, so we have to reset tx_dma_len accordingly. + */ + to_sci_port(port)->tx_dma_len =3D 0; +} +#else /* !CONFIG_SERIAL_SH_SCI_DMA */ static inline void sci_request_dma(struct uart_port *port) { } @@ -1551,7 +1560,9 @@ static inline void sci_request_dma(struct uart_port *= port) static inline void sci_free_dma(struct uart_port *port) { } -#endif + +#define sci_flush_buffer NULL +#endif /* !CONFIG_SERIAL_SH_SCI_DMA */ =20 static irqreturn_t sci_rx_interrupt(int irq, void *ptr) { @@ -2549,6 +2560,7 @@ static const struct uart_ops sci_uart_ops =3D { .break_ctl =3D sci_break_ctl, .startup =3D sci_startup, .shutdown =3D sci_shutdown, + .flush_buffer =3D sci_flush_buffer, .set_termios =3D sci_set_termios, .pm =3D sci_pm, .type =3D sci_type, --=20 2.14.1