[Devel] [PATCH rh7] vtty: Don't close unread master peer if slave is nonzero

[Konstantin Khorenko]

On 12/05/2015 08:21 PM, Cyrill Gorcunov wrote:
> When there are several files opened on /dev/console from inside
> of a container and noone hooked on master peer, any close called
> cause master peer to be freed with TTY_CLOSING bit set. So that
> next "vzctl console $ctid $ttynum" call force kernel to allocate
> new vtty pair and in result we can't login into the container.
>
> We've woraround master close when there is an active slave assigned
> but I miss the scenario when several fd = open(/dev/console) done and
> then one calls for close(fd).
>
> Lets test if master peer is about to close while there are still
> active slave (and move it into vtty_release helper).
>
> https://jira.sw.ru/browse/PSBM-41985
> https://jira.sw.ru/browse/PSBM-41672
>
> Signed-off-by: Cyrill Gorcunov <gorcunov at virtuozzo.com>
> CC: Vladimir Davydov <vdavydov at virtuozzo.com>
> CC: Konstantin Khorenko <khorenko at virtuozzo.com>
> ---
>   drivers/tty/pty.c    |   27 +++++++++++++++++++++++++++
>   drivers/tty/tty_io.c |    7 ++-----
>   include/linux/ve.h   |    2 ++
>   3 files changed, 31 insertions(+), 5 deletions(-)
>
> Index: linux-pcs7.git/drivers/tty/pty.c
> ===================================================================
> --- linux-pcs7.git.orig/drivers/tty/pty.c
> +++ linux-pcs7.git/drivers/tty/pty.c
> @@ -1259,6 +1259,33 @@ struct tty_driver *vtty_driver(dev_t dev
>   	return NULL;
>   }
>
> +void vtty_release(struct tty_struct *tty, struct tty_struct *o_tty,
> +		  int *tty_closing, int *o_tty_closing)
> +{
> +	lockdep_assert_held(&tty_mutex);
> +	int pty_master;

drivers/tty/pty.c: In function 'vtty_release':
drivers/tty/pty.c:1266:2: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
   int pty_master;
   ^
cc1: all warnings being treated as errors

Kirill, i'll fix it, so just take a note for the future.