diff options
| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2017-04-25 20:15:35 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-13 19:48:00 +0200 |
| commit | 13b9c31db4f2627920328f7010ed6a3bcb958e60 (patch) | |
| tree | f371851ddb2858723b93d71b50e841f69fdc73bd /drivers/tty | |
| parent | 65db56497574362f0f57f18f1f7ac8ff03926d17 (diff) | |
serial: sh-sci: Fix race condition causing garbage during shutdown
[ 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 <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/sh-sci.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index a55c94dfefd2..107f0d194ac5 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1545,7 +1545,16 @@ 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 = 0; +} +#else /* !CONFIG_SERIAL_SH_SCI_DMA */ static inline void sci_request_dma(struct uart_port *port) { } @@ -1553,7 +1562,9 @@ 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 */ static irqreturn_t sci_rx_interrupt(int irq, void *ptr) { @@ -2551,6 +2562,7 @@ static const struct uart_ops sci_uart_ops = { .break_ctl = sci_break_ctl, .startup = sci_startup, .shutdown = sci_shutdown, + .flush_buffer = sci_flush_buffer, .set_termios = sci_set_termios, .pm = sci_pm, .type = sci_type, |