tty/serial: lay the foundations for the next set of reworks

- Stop drivers calling their own flush method indirectly, it obfuscates code
  and it will change soon anyway

- A few more lock_kernel paths temporarily needed in some driver internal
  waiting code

- Remove private put_char method that does a write call for one char - we
  have that anyway

- Most but not yet all of the termios copy under lock fixing (some has other
  dependencies to follow)

- Note a few locking bugs in drivers found in the process

- Kill remaining [ab]users of TIOCG/SSOFTCAR in the driver, these must go to
  fix the termios locking

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index b716a73a236f..2f1988c48ee3 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -862,8 +862,7 @@ static void close(struct tty_struct *tty, struct file *filp)
         if (info->flags & ASYNC_INITIALIZED)
                 wait_until_sent(tty, info->timeout);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        flush_buffer(tty);
 
         tty_ldisc_flush(tty);
 
@@ -1119,6 +1118,8 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
         if (sanity_check(info, tty->name, "wait_until_sent"))
                 return;
 
+        lock_kernel();
+
         if (!(info->flags & ASYNC_INITIALIZED))
                 goto exit;
 
@@ -1161,6 +1162,7 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
         }
 
 exit:
+        unlock_kernel();
         if (debug_level >= DEBUG_LEVEL_INFO)
                 printk("%s(%d):%s wait_until_sent() exit\n",
                          __FILE__,__LINE__, info->device_name );
@@ -1176,6 +1178,7 @@ static int write_room(struct tty_struct *tty)
         if (sanity_check(info, tty->name, "write_room"))
                 return 0;
 
+        lock_kernel();
         if (info->params.mode == MGSL_MODE_HDLC) {
                 ret = (info->tx_active) ? 0 : HDLC_MAX_FRAME_SIZE;
         } else {
@@ -1183,6 +1186,7 @@ static int write_room(struct tty_struct *tty)
                 if (ret < 0)
                         ret = 0;
         }
+        unlock_kernel();
 
         if (debug_level >= DEBUG_LEVEL_INFO)
                 printk("%s(%d):%s write_room()=%d\n",