diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-04-17 19:16:26 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-22 16:23:37 +0200 |
| commit | 62b2caef400c1738b6d22f636c628d9f85cd4c4c (patch) | |
| tree | e4d24d6d27d756030551e35ec35c283e6d8270c8 | |
| parent | 8ec8719fc27b29c096340866cb3e618b8a4c81e4 (diff) | |
drivers: tty: serial: Fix deadlock in sa1100_set_termios()
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>
| -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 5fe6cccfc1ae..e64e42a19d1a 100644 --- a/drivers/tty/serial/sa1100.c +++ b/drivers/tty/serial/sa1100.c @@ -446,6 +446,8 @@ 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); @@ -476,8 +478,6 @@ 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. */ |