* [PATCH AUTOSEL 4.4 09/35] tty: serial: msm_serial: avoid system lockup condition
[not found] <20190719041423.19322-1-sashal@kernel.org>
@ 2019-07-19 4:13 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2019-07-19 4:13 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Jorge Ramirez-Ortiz, Greg Kroah-Hartman, Sasha Levin,
linux-arm-msm, linux-serial
From: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
[ Upstream commit ba3684f99f1b25d2a30b6956d02d339d7acb9799 ]
The function msm_wait_for_xmitr can be taken with interrupts
disabled. In order to avoid a potential system lockup - demonstrated
under stress testing conditions on SoC QCS404/5 - make sure we wait
for a bounded amount of time.
Tested on SoC QCS404.
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/msm_serial.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 5f0ded6fc4e9..eaeb098b5d6a 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -222,10 +222,14 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
static inline void msm_wait_for_xmitr(struct uart_port *port)
{
+ unsigned int timeout = 500000;
+
while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
break;
udelay(1);
+ if (!timeout--)
+ break;
}
msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);
}
--
2.20.1
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2019-07-19 4:13 ` [PATCH AUTOSEL 4.4 09/35] tty: serial: msm_serial: avoid system lockup condition Sasha Levin
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