[PATCH] tty locking on resize

The current kernel serializes console resizes but does not serialize the
resize against the tty structure updates.  This means that while two
parallel resizes cannot mess up the console you can get incorrect results
reported.

Secondly while doing this I added vc_lock_resize() to lock and resize the
console.  This leaves all knowledge of the console_sem in the vt/console
driver and kicks it out of the tty layer, which is good

Thirdly while doing this I decided I couldn't stand "disallocate" any
longer so I switched it to "deallocate".

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 0fca83ededff..b49f03375439 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -885,8 +885,17 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
         return err;
 }
 
+int vc_lock_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
+{
+        int rc;
+
+        acquire_console_sem();
+        rc = vc_resize(vc, cols, lines);
+        release_console_sem();
+        return rc;
+}
 
-void vc_disallocate(unsigned int currcons)
+void vc_deallocate(unsigned int currcons)
 {
         WARN_CONSOLE_UNLOCKED();
 
@@ -3790,6 +3799,7 @@ EXPORT_SYMBOL(default_blu);
 EXPORT_SYMBOL(update_region);
 EXPORT_SYMBOL(redraw_screen);
 EXPORT_SYMBOL(vc_resize);
+EXPORT_SYMBOL(vc_lock_resize);
 EXPORT_SYMBOL(fg_console);
 EXPORT_SYMBOL(console_blank_hook);
 EXPORT_SYMBOL(console_blanked);