tty_ioctl: locking for tty_wait_until_sent

This function still depends on the big kernel lock in some cases.  Push
locking into the function ready for removal of the BKL from ioctl call paths.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index d6353d89b451..851cfcd2702a 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -21,6 +21,7 @@
 #include <linux/module.h>
 #include <linux/bitops.h>
 #include <linux/mutex.h>
+#include <linux/smp_lock.h>
 
 #include <asm/io.h>
 #include <asm/uaccess.h>
@@ -61,11 +62,13 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout)
                 return;
         if (!timeout)
                 timeout = MAX_SCHEDULE_TIMEOUT;
+        lock_kernel();
         if (wait_event_interruptible_timeout(tty->write_wait,
-                        !tty->driver->chars_in_buffer(tty), timeout) < 0)
-                return;
-        if (tty->driver->wait_until_sent)
-                tty->driver->wait_until_sent(tty, timeout);
+                        !tty->driver->chars_in_buffer(tty), timeout) >= 0) {
+                if (tty->driver->wait_until_sent)
+                        tty->driver->wait_until_sent(tty, timeout);
+        }
+        unlock_kernel();
 }
 EXPORT_SYMBOL(tty_wait_until_sent);