tty: release BTM while sleeping in block_til_ready

Most tty drivers may block while opening a device.
Since this possibly depends on another thread
closing it first and both threads may need the BTM,
we need to release it here.

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>

8 files changed, 19 insertions, 1 deletions

diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 8228e61bb54d..a11c8c9ca3d4 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -1710,7 +1710,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
                 printk("block_til_ready blocking: ttys%d, count = %d\n",
                        info->line, state->count);
 #endif
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
         __set_current_state(TASK_RUNNING);
         remove_wait_queue(&info->open_wait, &wait);
diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index 911e1da6def2..07f3ea38b582 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -1486,7 +1486,9 @@ ip2_open( PTTY tty, struct file *pFile )
 
         if ( tty_hung_up_p(pFile) || ( pCh->flags & ASYNC_CLOSING )) {
                 if ( pCh->flags & ASYNC_CLOSING ) {
+                        tty_unlock();
                         schedule();
+                        tty_lock();
                 }
                 if ( tty_hung_up_p(pFile) ) {
                         set_current_state( TASK_RUNNING );
@@ -1548,7 +1550,9 @@ ip2_open( PTTY tty, struct file *pFile )
                         rc = (( pCh->flags & ASYNC_HUP_NOTIFY ) ? -EAGAIN : -ERESTARTSYS);
                         break;
                 }
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
         set_current_state( TASK_RUNNING );
         remove_wait_queue(&pCh->open_wait, &wait);
diff --git a/drivers/char/serial167.c b/drivers/char/serial167.c
index 90b3ec0aabdd..f646725bd567 100644
--- a/drivers/char/serial167.c
+++ b/drivers/char/serial167.c
@@ -1786,7 +1786,9 @@ block_til_ready(struct tty_struct *tty, struct file *filp,
                        tty->name, info->count);
                 /**/
 #endif
-                    schedule();
+                tty_unlock();
+                schedule();
+                tty_lock();
         }
         __set_current_state(TASK_RUNNING);
         remove_wait_queue(&info->open_wait, &wait);
diff --git a/drivers/char/specialix.c b/drivers/char/specialix.c
index 7be456f760c9..9f8495b4fc8f 100644
--- a/drivers/char/specialix.c
+++ b/drivers/char/specialix.c
@@ -1365,7 +1365,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                         retval = -ERESTARTSYS;
                         break;
                 }
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
 
         set_current_state(TASK_RUNNING);
diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index 2b03d4d47350..a2a58004e188 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -3349,7 +3349,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
                         printk("%s(%d):block_til_ready blocking on %s count=%d\n",
                                  __FILE__,__LINE__, tty->driver->name, port->count );
                                  
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
         
         set_current_state(TASK_RUNNING);
diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 5a602eb7cd2d..fef80cfcab5c 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -3244,7 +3244,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                 }
 
                 DBGINFO(("%s block_til_ready wait\n", tty->driver->name));
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
 
         set_current_state(TASK_RUNNING);
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index ac447c7eb572..e56caf7d82aa 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -3365,7 +3365,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                         printk("%s(%d):%s block_til_ready() count=%d\n",
                                  __FILE__,__LINE__, tty->driver->name, port->count );
 
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
 
         set_current_state(TASK_RUNNING);
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 35eb30402f18..33d37d230f8f 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -294,7 +294,9 @@ int tty_port_block_til_ready(struct tty_port *port,
                         retval = -ERESTARTSYS;
                         break;
                 }
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
         finish_wait(&port->open_wait, &wait);