| Message ID | 9ca3ab0b40c875b6019f32f031c68a1ae80dd73a.1649310812.git.duoming@zju.edu.cn |
|---|---|
| State | New |
| Headers | show |
| Series | None | expand |
diff --git a/arch/xtensa/platforms/iss/console.c b/arch/xtensa/platforms/iss/console.c index 81d7c7e8f7e..d431b61ae3c 100644 --- a/arch/xtensa/platforms/iss/console.c +++ b/arch/xtensa/platforms/iss/console.c @@ -51,8 +51,10 @@ static int rs_open(struct tty_struct *tty, struct file * filp) static void rs_close(struct tty_struct *tty, struct file * filp) { spin_lock_bh(&timer_lock); - if (tty->count == 1) + if (tty->count == 1) { + spin_unlock_bh(&timer_lock); del_timer_sync(&serial_timer); + } spin_unlock_bh(&timer_lock); }
There is a deadlock in rs_close(), which is shown below: (Thread 1) | (Thread 2) | rs_open() rs_close() | mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rs_poll() del_timer_sync() | spin_lock() //(2) (wait timer to stop) | ... We hold timer_lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need timer_lock in position (2) of thread 2. As a result, rs_close() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- arch/xtensa/platforms/iss/console.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)