tty: core: Improve debug message content

Output the function name, tty name, and invariant failure (if applicable).
Add the tty count to the tty_open() message. Fix the disassociate_ctty()
message, which printed the NULL pointer and the wrong message.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 16 insertions, 13 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 6bdfb98bf020..1738fcaea891 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -531,7 +531,8 @@ static void __proc_set_tty(struct tty_struct *tty)
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
         tty->session = get_pid(task_session(current));
         if (current->signal->tty) {
-                printk(KERN_DEBUG "tty not NULL!!\n");
+                printk(KERN_DEBUG "%s: %s: current tty %s not NULL!!\n",
+                       __func__, tty->name, current->signal->tty->name);
                 tty_kref_put(current->signal->tty);
         }
         put_pid(current->signal->tty_old_pgrp);
@@ -929,8 +930,7 @@ void disassociate_ctty(int on_exit)
                 tty_kref_put(tty);
         } else {
 #ifdef TTY_DEBUG_HANGUP
-                printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
-                       " = NULL", tty);
+                printk(KERN_DEBUG "%s: no current tty\n", __func__);
 #endif
         }
 
@@ -1712,8 +1712,8 @@ static int tty_release_checks(struct tty_struct *tty, int idx)
 {
 #ifdef TTY_PARANOIA_CHECK
         if (idx < 0 || idx >= tty->driver->num) {
-                printk(KERN_DEBUG "%s: bad idx when trying to free (%s)\n",
-                                __func__, tty->name);
+                printk(KERN_DEBUG "%s: %s: bad idx %d\n",
+                                __func__, tty->name, idx);
                 return -1;
         }
 
@@ -1722,20 +1722,22 @@ static int tty_release_checks(struct tty_struct *tty, int idx)
                 return 0;
 
         if (tty != tty->driver->ttys[idx]) {
-                printk(KERN_DEBUG "%s: driver.table[%d] not tty for (%s)\n",
-                                __func__, idx, tty->name);
+                printk(KERN_DEBUG "%s: %s: bad driver table[%d] = %p\n",
+                       __func__, tty->name, idx, tty->driver->ttys[idx]);
                 return -1;
         }
         if (tty->driver->other) {
                 struct tty_struct *o_tty = tty->link;
 
                 if (o_tty != tty->driver->other->ttys[idx]) {
-                        printk(KERN_DEBUG "%s: other->table[%d] not o_tty for (%s)\n",
-                                        __func__, idx, tty->name);
+                        printk(KERN_DEBUG "%s: %s: bad other table[%d] = %p\n",
+                               __func__, tty->name, idx,
+                               tty->driver->other->ttys[idx]);
                         return -1;
                 }
                 if (o_tty->link != tty) {
-                        printk(KERN_DEBUG "%s: bad pty pointers\n", __func__);
+                        printk(KERN_DEBUG "%s: %s: bad link = %p\n",
+                               __func__, tty->name, o_tty->link);
                         return -1;
                 }
         }
@@ -2106,7 +2108,8 @@ retry_open:
             tty->driver->subtype == PTY_TYPE_MASTER)
                 noctty = 1;
 #ifdef TTY_DEBUG_HANGUP
-        printk(KERN_DEBUG "%s: opening %s...\n", __func__, tty->name);
+        printk(KERN_DEBUG "%s: %s: (tty count=%d)\n", __func__, tty->name,
+               tty->count);
 #endif
         if (tty->ops->open)
                 retval = tty->ops->open(tty, filp);
@@ -2116,8 +2119,8 @@ retry_open:
 
         if (retval) {
 #ifdef TTY_DEBUG_HANGUP
-                printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
-                                retval, tty->name);
+                printk(KERN_DEBUG "%s: %s: error %d, releasing...\n", __func__,
+                       tty->name, retval);
 #endif
                 tty_unlock(tty); /* need to call tty_release without BTM */
                 tty_release(inode, filp);