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| author | Jiri Slaby <jslaby@suse.cz> | 2011-08-25 13:12:05 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-08-25 16:00:39 (GMT) |
| commit | bafb0bd24d7e0e0124318625b239a55d58c757a2 (patch) | |
| tree | c5e262faa274ed54696cfb433717b99ddcee966c | |
| parent | 426929f8d3514d7f727b8c464d1eeeaf74b21519 (diff) | |
| download | linux-bafb0bd24d7e0e0124318625b239a55d58c757a2.tar.xz | |
TTY: serial, move locking in uart_close
So now, when we handle CLOSING flag, there is no point to hold
port->mutex over the start of uart_close.
Yes, there are still several things to reason about:
* port->count etc is and always was protected by a spinlock
* ->stop_rx is protected by a spinlock. Otherwise it would
race with interrupts.
* uart_wait_until_sent -- that one is already called without
port->mutex from set_termios and tty_set_ldisc. Should anything
be protected there, it would be tx_empty. And by a spinlock.
8250 does this internally...
This step is needed to fix system stalls. To not create an AB-BA lock
dependency (see next patches).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 849bd0d..0464360 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1253,7 +1253,6 @@ static void uart_close(struct tty_struct *tty, struct file *filp) pr_debug("uart_close(%d) called\n", uport->line); - mutex_lock(&port->mutex); spin_lock_irqsave(&port->lock, flags); if (tty_hung_up_p(filp)) { @@ -1312,6 +1311,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp) uart_wait_until_sent(tty, uport->timeout); } + mutex_lock(&port->mutex); uart_shutdown(tty, state); uart_flush_buffer(tty); |