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TTY: ldisc, allow waiting for ldisc arbitrarily long

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To fix a nasty bug in ldisc hup vs. reinit we need to wait infinitely
long for ldisc to be gone. So here we add a parameter to
tty_ldisc_wait_idle to allow that.

This is only a preparation for the real fix which is done in the
following patches.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Dmitriy Matrosov <sgf.dma@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Jiri Slaby
2011-11-16 16:27:07 +01:00
committed by Greg Kroah-Hartman
parent 6edf0c9b1c
commit df92d0561d
1 changed files with 6 additions and 5 deletions
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11
drivers/tty/tty_ldisc.c
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@@ -547,15 +547,16 @@ static void tty_ldisc_flush_works(struct tty_struct *tty)
/** /**
* tty_ldisc_wait_idle - wait for the ldisc to become idle * tty_ldisc_wait_idle - wait for the ldisc to become idle
* @tty: tty to wait for * @tty: tty to wait for
* @timeout: for how long to wait at most
* *
* Wait for the line discipline to become idle. The discipline must * Wait for the line discipline to become idle. The discipline must
* have been halted for this to guarantee it remains idle. * have been halted for this to guarantee it remains idle.
*/ */
static int tty_ldisc_wait_idle(struct tty_struct *tty) static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)
{ {
int ret; long ret;
ret = wait_event_timeout(tty_ldisc_idle, ret = wait_event_timeout(tty_ldisc_idle,
atomic_read(&tty->ldisc->users) == 1, 5 * HZ); atomic_read(&tty->ldisc->users) == 1, timeout);
if (ret < 0) if (ret < 0)
return ret; return ret;
return ret > 0 ? 0 : -EBUSY; return ret > 0 ? 0 : -EBUSY;
@@ -665,7 +666,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_ldisc_flush_works(tty); tty_ldisc_flush_works(tty);
retval = tty_ldisc_wait_idle(tty); retval = tty_ldisc_wait_idle(tty, 5 * HZ);
tty_lock(); tty_lock();
mutex_lock(&tty->ldisc_mutex); mutex_lock(&tty->ldisc_mutex);
@@ -762,7 +763,7 @@ static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
if (IS_ERR(ld)) if (IS_ERR(ld))
return -1; return -1;
WARN_ON_ONCE(tty_ldisc_wait_idle(tty)); WARN_ON_ONCE(tty_ldisc_wait_idle(tty, 5 * HZ));
tty_ldisc_close(tty, tty->ldisc); tty_ldisc_close(tty, tty->ldisc);
tty_ldisc_put(tty->ldisc); tty_ldisc_put(tty->ldisc);