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author | Jiri Slaby <jslaby@suse.cz> | 2011-08-10 14:59:28 +0200 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-03 11:39:49 -0700 |
commit | a38df1a01320298198c7cb2e3e8a61fc54459d6a (patch) | |
tree | 358a4b7c1a12a3ac49fa41c9baea128de9577734 /include/linux/hippidevice.h | |
parent | 64da3499c911698c004a2d47fd0af6ad683a811a (diff) |
TTY: pty, fix pty counting
commit 24d406a6bf736f7aebdc8fa0f0ec86e0890c6d24 upstream.
tty_operations->remove is normally called like:
queue_release_one_tty
->tty_shutdown
->tty_driver_remove_tty
->tty_operations->remove
However tty_shutdown() is called from queue_release_one_tty() only if
tty_operations->shutdown is NULL. But for pty, it is not.
pty_unix98_shutdown() is used there as ->shutdown.
So tty_operations->remove of pty (i.e. pty_unix98_remove()) is never
called. This results in invalid pty_count. I.e. what can be seen in
/proc/sys/kernel/pty/nr.
I see this was already reported at:
https://lkml.org/lkml/2009/11/5/370
But it was not fixed since then.
This patch is kind of a hackish way. The problem lies in ->install. We
allocate there another tty (so-called tty->link). So ->install is
called once, but ->remove twice, for both tty and tty->link. The fix
here is to count both tty and tty->link and divide the count by 2 for
user.
And to have ->remove called, let's make tty_driver_remove_tty() global
and call that from pty_unix98_shutdown() (tty_operations->shutdown).
While at it, let's document that when ->shutdown is defined,
tty_shutdown() is not called.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux/hippidevice.h')
0 files changed, 0 insertions, 0 deletions