diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-04-17 19:16:26 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-14 16:59:37 +0200 |
| commit | 920f0ae7a129ffee98a106e3bbdfd61a2a59e939 (patch) | |
| tree | e0c4fa57e1975d8bfa061747f9c91132c21725c8 | |
| parent | 3825db88d8c704e7992b685618a03f82bffcf2ef (diff) | |
drivers: tty: serial: Fix deadlock in sa1100_set_termios()
[ Upstream commit 62b2caef400c1738b6d22f636c628d9f85cd4c4c ]
There is a deadlock in sa1100_set_termios(), which is shown
below:
(Thread 1) | (Thread 2)
| sa1100_enable_ms()
sa1100_set_termios() | mod_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | sa1100_timeout()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold sport->port.lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need sport->port.lock in position (2) of thread 2. As a result,
sa1100_set_termios() will block forever.
This patch moves del_timer_sync() before spin_lock_irqsave()
in order to prevent the deadlock.
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20220417111626.7802-1-duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/tty/serial/sa1100.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/serial/sa1100.c b/drivers/tty/serial/sa1100.c index a399772be3fc..8a65fb1ce568 100644 --- a/drivers/tty/serial/sa1100.c +++ b/drivers/tty/serial/sa1100.c @@ -439,6 +439,8 @@ sa1100_set_termios(struct uart_port *port, struct ktermios *termios, baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); quot = uart_get_divisor(port, baud); + del_timer_sync(&sport->timer); + spin_lock_irqsave(&sport->port.lock, flags); sport->port.read_status_mask &= UTSR0_TO_SM(UTSR0_TFS); @@ -469,8 +471,6 @@ sa1100_set_termios(struct uart_port *port, struct ktermios *termios, UTSR1_TO_SM(UTSR1_ROR); } - del_timer_sync(&sport->timer); - /* * Update the per-port timeout. */ |