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author | Jiri Slaby <jslaby@suse.cz> | 2011-08-10 14:59:28 +0200 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-08-23 10:10:38 -0700 |
commit | 24d406a6bf736f7aebdc8fa0f0ec86e0890c6d24 (patch) | |
tree | 3dfb2053f7785508304fd29d6c1bb6e6a42a7d5c /drivers/tty/tty_io.c | |
parent | dbb3b1ca5609d1f3848cd387d06cc60aaacf7f98 (diff) | |
download | linux-24d406a6bf736f7aebdc8fa0f0ec86e0890c6d24.tar.gz |
TTY: pty, fix pty counting
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> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty/tty_io.c')
-rw-r--r-- | drivers/tty/tty_io.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 150e4f747c7d..4f1fc81112e6 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1295,8 +1295,7 @@ static int tty_driver_install_tty(struct tty_driver *driver, * * Locking: tty_mutex for now */ -static void tty_driver_remove_tty(struct tty_driver *driver, - struct tty_struct *tty) +void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty) { if (driver->ops->remove) driver->ops->remove(driver, tty); |