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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 5.2 049/171] tty: serial: msm_serial: avoid system lockup condition
Date: Thu, 18 Jul 2019 23:54:40 -0400
Message-ID: <20190719035643.14300-49-sashal@kernel.org> (raw)
In-Reply-To: <20190719035643.14300-1-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 23833ad952ba..3657a24913fc 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -383,10 +383,14 @@ 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


  parent reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190719035643.14300-1-sashal@kernel.org>
2019-07-19  3:54 ` [PATCH AUTOSEL 5.2 016/171] drm/msm/a6xx: Check for ERR or NULL before iounmap Sasha Levin
2019-07-19  3:54 ` [PATCH AUTOSEL 5.2 020/171] drm/msm/a6xx: Avoid freeing gmu resources multiple times Sasha Levin
2019-07-19  3:54 ` Sasha Levin [this message]
2019-07-19  3:55 ` [PATCH AUTOSEL 5.2 076/171] drm/msm/adreno: Ensure that the zap shader region is big enough Sasha Levin
2019-07-19  3:55 ` [PATCH AUTOSEL 5.2 078/171] drm/msm: Depopulate platform on probe failure Sasha Levin

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