From 19331fd9b8a8fa1821f3a6d1342c1ca2a499be97 Mon Sep 17 00:00:00 2001 From: Jorge Ramirez-Ortiz Date: Mon, 10 Jun 2019 19:23:08 +0200 Subject: [PATCH] tty: serial: msm_serial: avoid system lockup condition [ 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- 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 @@ no_rx: 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