[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, 7 insertions, 10 deletions

diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index a5628a8b6620..a53e382cc107 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -96,7 +96,7 @@ do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm, struct kbd_str
                 if (!perm)
                         return -EPERM;
                 if (!i && v == K_NOSUCHMAP) {
-                        /* disallocate map */
+                        /* deallocate map */
                         key_map = key_maps[s];
                         if (s && key_map) {
                             key_maps[s] = NULL;
@@ -819,20 +819,20 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
                 if (arg > MAX_NR_CONSOLES)
                         return -ENXIO;
                 if (arg == 0) {
-                    /* disallocate all unused consoles, but leave 0 */
+                    /* deallocate all unused consoles, but leave 0 */
                         acquire_console_sem();
                         for (i=1; i<MAX_NR_CONSOLES; i++)
                                 if (! VT_BUSY(i))
-                                        vc_disallocate(i);
+                                        vc_deallocate(i);
                         release_console_sem();
                 } else {
-                        /* disallocate a single console, if possible */
+                        /* deallocate a single console, if possible */
                         arg--;
                         if (VT_BUSY(arg))
                                 return -EBUSY;
                         if (arg) {                            /* leave 0 */
                                 acquire_console_sem();
-                                vc_disallocate(arg);
+                                vc_deallocate(arg);
                                 release_console_sem();
                         }
                 }
@@ -847,11 +847,8 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
                 if (get_user(ll, &vtsizes->v_rows) ||
                     get_user(cc, &vtsizes->v_cols))
                         return -EFAULT;
-                for (i = 0; i < MAX_NR_CONSOLES; i++) {
-                        acquire_console_sem();
-                        vc_resize(vc_cons[i].d, cc, ll);
-                        release_console_sem();
-                }
+                for (i = 0; i < MAX_NR_CONSOLES; i++)
+                        vc_lock_resize(vc_cons[i].d, cc, ll);
                 return 0;
         }