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tty: Add ldisc hangup debug messages

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Expected typical debug log:
[  582.721965] tty_open: opening pts3...
[  582.721970] tty_open: opening pts3...
[  582.721977] tty_release: pts3 (tty count=3)...
[  582.721980] tty_release: ptm3 (tty count=1)...
[  582.722015] pts3 vhangup...
[  582.722020] tty_ldisc_hangup: pts3: closing ldisc: ffff88007a920540
[  582.724128] tty_release: pts3 (tty count=2)...
[  582.724217] tty_ldisc_hangup: pts3: re-opened ldisc: ffff88007a920580
[  582.724221] tty_release: ptm3: final close
[  582.724234] tty_ldisc_release: ptm3: closing ldisc: ffff88007a920a80
[  582.724238] tty_ldisc_release: ptm3: ldisc closed
[  582.724241] tty_release: ptm3: freeing structure...
[  582.724741] tty_open: opening pts3...

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2013-03-11 16:44:38 -04:00 committed by Greg Kroah-Hartman
parent 96433d104a
commit fc575ee6ea
1 changed files with 19 additions and 0 deletions
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19
drivers/tty/tty_ldisc.c
View file

@ -20,6 +20,17 @@
#include <linux/uaccess.h>
#include <linux/ratelimit.h>
#undef LDISC_DEBUG_HANGUP
#ifdef LDISC_DEBUG_HANGUP
#define tty_ldisc_debug(tty, f, args...) ({ \
char __b[64]; \
printk(KERN_DEBUG "%s: %s: " f, __func__, tty_name(tty, __b), ##args); \
})
#else
#define tty_ldisc_debug(tty, f, args...)
#endif
/*
* This guards the refcounted line discipline lists. The lock
* must be taken with irqs off because there are hangup path
@ -822,6 +833,8 @@ void tty_ldisc_hangup(struct tty_struct *tty)
int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS;
int err = 0;
tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc);
/*
* FIXME! What are the locking issues here? This may me overdoing
* things... This question is especially important now that we've
@ -878,6 +891,8 @@ void tty_ldisc_hangup(struct tty_struct *tty)
mutex_unlock(&tty->ldisc_mutex);
if (reset)
tty_reset_termios(tty);
tty_ldisc_debug(tty, "re-opened ldisc: %p\n", tty->ldisc);
}
/**
@ -944,6 +959,8 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
* it does not race with the set_ldisc code path.
*/
tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc);
tty_ldisc_halt(tty, o_tty, MAX_SCHEDULE_TIMEOUT);
tty_lock_pair(tty, o_tty);
@ -955,6 +972,8 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
tty_unlock_pair(tty, o_tty);
/* And the memory resources remaining (buffers, termios) will be
disposed of when the kref hits zero */
tty_ldisc_debug(tty, "ldisc closed\n");
}
/**