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tty: never hold BTM while getting tty_mutex

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tty_mutex is never taken with the BTM held, except for
two corner cases that are worked around here.
We give up the BTM before calling tty_release() in the
error path of tty_open().
Similarly, we reorder the locking in ptmx_open()
to get tty_mutex before the BTM.

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>
This commit is contained in:
Arnd Bergmann
2010-06-01 22:53:02 +02:00
committed by Greg Kroah-Hartman
parent ec79d6056d
commit 64ba3dc314
2 changed files with 17 additions and 19 deletions
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12
drivers/char/tty_io.c
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@@ -1866,19 +1866,19 @@ got_driver:
printk(KERN_DEBUG "error %d in opening %s...", retval,
tty->name);
#endif
tty_unlock(); /* need to call tty_release without BTM */
tty_release(inode, filp);
if (retval != -ERESTARTSYS) {
tty_unlock();
if (retval != -ERESTARTSYS)
return retval;
}
if (signal_pending(current)) {
tty_unlock();
if (signal_pending(current))
return retval;
}
schedule();
/*
* Need to reset f_op in case a hangup happened.
*/
tty_lock();
if (filp->f_op == &hung_up_tty_fops)
filp->f_op = &tty_fops;
tty_unlock();