From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 13/60] tty: serial: msm_serial: avoid system lockup condition
Date: Fri, 19 Jul 2019 00:10:22 -0400 [thread overview]
Message-ID: <20190719041109.18262-13-sashal@kernel.org> (raw)
In-Reply-To: <20190719041109.18262-1-sashal@kernel.org>
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 716aa76abdf9..0e0ccc132ab0 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -391,10 +391,14 @@ 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
next parent reply other threads:[~2019-07-19 4:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190719041109.18262-1-sashal@kernel.org>
2019-07-19 4:10 ` Sasha Levin [this message]
2019-07-19 4:10 ` [PATCH AUTOSEL 4.14 24/60] drm/msm: Depopulate platform on probe failure Sasha Levin
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