Char: moxa, fix locking in moxa_write

moxa_write can be called from atomic context with irqs disabled (from
ppp_async_push). Don't enable interrupts by spin_unlock_bh as this
might cause deadlocks in the ppp layer.

Instead, use irqsave/irqrestore spin_lock functions.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/moxa.c b/drivers/tty/moxa.c
index a290e9e..6255561 100644 (file)
--- a/drivers/tty/moxa.c
+++ b/drivers/tty/moxa.c
@@ -1202,14 +1202,15 @@ static int moxa_write(struct tty_struct *tty,
                      const unsigned char *buf, int count)
 {
        struct moxa_port *ch = tty->driver_data;
+       unsigned long flags;
        int len;
 
        if (ch == NULL)
                return 0;
 
-       spin_lock_bh(&moxa_lock);
+       spin_lock_irqsave(&moxa_lock, flags);
        len = MoxaPortWriteData(tty, buf, count);
-       spin_unlock_bh(&moxa_lock);
+       spin_unlock_irqrestore(&moxa_lock, flags);
 
        set_bit(LOWWAIT, &ch->statusflags);
        return len;