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vt: Deadlock workaround 

2.6.26 corrected the mutex locking on tty resizing to fix the case where
you could get the tty/vt sizing out of sync. That turns out to have a
deadlock.

The actual fix is really major and I've got it lined up as part of the ops
changes for 2.6.28 so for 2.6.26/2.6.27 it is safer to reintroduce this
ages old minor bug.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2008-08-04 17:47:07 +01:00 committed by Linus Torvalds
parent d728335322
commit d5cae36414
1 changed files with 0 additions and 2 deletions
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2
drivers/char/vt.c
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@ -916,7 +916,6 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
ws.ws_col = vc->vc_cols; ws.ws_col = vc->vc_cols;
ws.ws_ypixel = vc->vc_scan_lines; ws.ws_ypixel = vc->vc_scan_lines;
mutex_lock(&vc->vc_tty->termios_mutex);
spin_lock_irq(&vc->vc_tty->ctrl_lock); spin_lock_irq(&vc->vc_tty->ctrl_lock);
if ((ws.ws_row != cws->ws_row || ws.ws_col != cws->ws_col)) if ((ws.ws_row != cws->ws_row || ws.ws_col != cws->ws_col))
pgrp = get_pid(vc->vc_tty->pgrp); pgrp = get_pid(vc->vc_tty->pgrp);
@ -926,7 +925,6 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
put_pid(pgrp); put_pid(pgrp);
} }
*cws = ws; *cws = ws;
mutex_unlock(&vc->vc_tty->termios_mutex);
} }
if (CON_IS_VISIBLE(vc)) if (CON_IS_VISIBLE(vc))