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[PATCH] tty locking on resize

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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>
This commit is contained in:
Alan Cox
2006-09-29 02:00:03 -07:00
committed by Linus Torvalds
parent ae78bf9c4f
commit ca9bda00b4
5 changed files with 36 additions and 27 deletions
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17
drivers/char/vt_ioctl.c
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@@ -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;
}