diff options
| author |   Daniel Jedrychowski <avistel@gmail.com> | 2016-12-12 09:18:28 +1100 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-11 08:35:17 +0100 |
| commit | 2bed8a8e70729f996af92042d3ad0f11870acc1f (patch) | |
| tree | bef2d20e174c126ea18ad33cb4f7c0a9790b08a2 /drivers | |
| parent | 8250_pci: Fix potential use-after-free in error path (diff) | |
| download | linux-dev-2bed8a8e70729f996af92042d3ad0f11870acc1f.tar.xz linux-dev-2bed8a8e70729f996af92042d3ad0f11870acc1f.zip | |
Clearing FIFOs in RS485 emulation mode causes subsequent transmits to break
When in RS485 emulation mode, __do_stop_tx_rs485() calls
serial8250_clear_fifos(). This not only clears the FIFOs, but also sets
all bits in their control register (UART_FCR) to 0.
One of the effects of this is the disabling of the FIFOs, which turns
them into single-byte holding registers. The rest of the driver doesn't
know this, which results in the lions share of characters passed into a
write call to be dropped.
(I can supply logic analyzer screenshots if necessary)
This fix replaces the serial8250_clear_fifos() call to
serial8250_clear_and_reinit_fifos() - this prevents the "dropped
characters" issue from manifesting again while retaining the requirement
of clearing the RX FIFO after transmission if the SER_RS485_RX_DURING_TX
flag is disabled.
Signed-off-by: Daniel Jedrychowski <avistel@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index fe4399b41df6..c13fec451d03 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1413,7 +1413,7 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p) * Enable previously disabled RX interrupts. */ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) { - serial8250_clear_fifos(p); + serial8250_clear_and_reinit_fifos(p); p->ier |= UART_IER_RLSI | UART_IER_RDI; serial_port_out(&p->port, UART_IER, p->ier); |