tty: untangle locking of wait_until_sent

Some wait_until_sent versions require the big
tty mutex, others don't and some callers of
wait_until_sent already hold it while other don't.
That leads to recursive use of the BTM in these
functions, which we're trying to get rid of.

This turns all cleans up the locking there so
that the driver's wait_until_sent function
never takes the BTM itself if it is already
called with that lock held.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index 94bfb9f238e1..8e356c5eeae0 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3935,7 +3935,6 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
          * Check R_DMA_CHx_STATUS bit 0-6=number of available bytes in FIFO
          * R_DMA_CHx_HWSW bit 31-16=nbr of bytes left in DMA buffer (0=64k)
          */
-        tty_lock_nested(); /* locked already when coming from close */
         orig_jiffies = jiffies;
         while (info->xmit.head != info->xmit.tail || /* More in send queue */
                (*info->ostatusadr & 0x007f) ||  /* more in FIFO */
@@ -3952,7 +3951,6 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
                         curr_time_usec - info->last_tx_active_usec;
         }
         set_current_state(TASK_RUNNING);
-        tty_unlock();
 }
 
 /*