diff options
| author |   Dmitry Safonov <dima@arista.com> | 2018-11-01 00:24:48 +0000 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-05 12:16:33 +0100 |
| commit | c96cf923a98d1b094df9f0cf97a83e118817e31b (patch) | |
| tree | 600f4d868ef87ff58a642bb7e6d4825894d9c657 /drivers/tty/n_r3964.c | |
| parent | tty: Hold tty_ldisc_lock() during tty_reopen() (diff) | |
| download | linux-dev-c96cf923a98d1b094df9f0cf97a83e118817e31b.tar.xz linux-dev-c96cf923a98d1b094df9f0cf97a83e118817e31b.zip | |
tty: Don't block on IO when ldisc change is pending
There might be situations where tty_ldisc_lock() has blocked, but there
is already IO on tty and it prevents line discipline changes.
It might theoretically turn into dead-lock.
Basically, provide more priority to pending tty_ldisc_lock() than to
servicing reads/writes over tty.
User-visible issue was reported by Mikulas where on pa-risc with
Debian 5 reboot took either 80 seconds, 3 minutes or 3:25 after proper
locking in tty_reopen().
Cc: Jiri Slaby <jslaby@suse.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_r3964.c')
| -rw-r--r-- | drivers/tty/n_r3964.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/n_r3964.c b/drivers/tty/n_r3964.c index 749a608c40b0..f75696f0ee2d 100644 --- a/drivers/tty/n_r3964.c +++ b/drivers/tty/n_r3964.c @@ -1085,7 +1085,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file, pMsg = remove_msg(pInfo, pClient); if (pMsg == NULL) { /* no messages available. */ - if (file->f_flags & O_NONBLOCK) { + if (tty_io_nonblock(tty, file)) { ret = -EAGAIN; goto unlock; } |