TTY: isdn/gigaset, do not set tty->driver_data to NULL

Close the window in open where driver_data is reset to NULL on each
open. It could cause other processes to get invalid retval from the
tty->ops operations because of the checks all over the code.

With this change we may do other cleanups. Now, the only valid check
for tty->driver_data != NULL is in close. This can happen only if open
fails at gigaset_get_cs_by_tty or try_module_get. The rest of checks
in various tty->ops->* are invalid as driver_data cannot be NULL
there. The same holds for cs->open_count. So remove them.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Hansjoerg Lipp <hjlipp@web.de>
Cc: Tilman Schmidt <tilman@imap.cc>
Cc: gigaset307x-common@lists.sourceforge.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/isdn/gigaset/interface.c b/drivers/isdn/gigaset/interface.c
index 648260b07f1a10a1f51ed6c2c3741b55c0a79bd5..8ff50b05628557d95af9511120e84536b11b07d5 100644 (file)
--- a/drivers/isdn/gigaset/interface.c
+++ b/drivers/isdn/gigaset/interface.c
@@ -151,8 +151,6 @@ static int if_open(struct tty_struct *tty, struct file *filp)
        gig_dbg(DEBUG_IF, "%d+%d: %s()",
                tty->driver->minor_start, tty->index, __func__);
 
-       tty->driver_data = NULL;
-
        cs = gigaset_get_cs_by_tty(tty);
        if (!cs || !try_module_get(cs->driver->owner))
                return -ENODEV;
@@ -178,12 +176,11 @@ static int if_open(struct tty_struct *tty, struct file *filp)
 
 static void if_close(struct tty_struct *tty, struct file *filp)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        unsigned long flags;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
+       if (!cs) { /* happens if we didn't find cs in open */
+               printk(KERN_DEBUG "%s: no cardstate\n", __func__);
                return;
        }
 
@@ -211,18 +208,12 @@ static void if_close(struct tty_struct *tty, struct file *filp)
 static int if_ioctl(struct tty_struct *tty,
                    unsigned int cmd, unsigned long arg)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        int retval = -ENODEV;
        int int_arg;
        unsigned char buf[6];
        unsigned version[4];
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return -ENODEV;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s(0x%x)", cs->minor_index, __func__, cmd);
 
        if (mutex_lock_interruptible(&cs->mutex))
@@ -231,9 +222,7 @@ static int if_ioctl(struct tty_struct *tty,
        if (!cs->connected) {
                gig_dbg(DEBUG_IF, "not connected");
                retval = -ENODEV;
-       } else if (!cs->open_count)
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
-       else {
+       } else {
                retval = 0;
                switch (cmd) {
                case GIGASET_REDIR:
@@ -285,15 +274,9 @@ static int if_ioctl(struct tty_struct *tty,
 
 static int if_tiocmget(struct tty_struct *tty)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        int retval;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return -ENODEV;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
        if (mutex_lock_interruptible(&cs->mutex))
@@ -309,16 +292,10 @@ static int if_tiocmget(struct tty_struct *tty)
 static int if_tiocmset(struct tty_struct *tty,
                       unsigned int set, unsigned int clear)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        int retval;
        unsigned mc;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return -ENODEV;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s(0x%x, 0x%x)",
                cs->minor_index, __func__, set, clear);
 
@@ -341,16 +318,10 @@ static int if_tiocmset(struct tty_struct *tty,
 
 static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        struct cmdbuf_t *cb;
        int retval;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return -ENODEV;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
        if (mutex_lock_interruptible(&cs->mutex))
@@ -361,11 +332,6 @@ static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
                retval = -ENODEV;
                goto done;
        }
-       if (!cs->open_count) {
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
-               retval = -ENODEV;
-               goto done;
-       }
        if (cs->mstate != MS_LOCKED) {
                dev_warn(cs->dev, "can't write to unlocked device\n");
                retval = -EBUSY;
@@ -397,15 +363,9 @@ done:
 
 static int if_write_room(struct tty_struct *tty)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        int retval = -ENODEV;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return -ENODEV;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
        if (mutex_lock_interruptible(&cs->mutex))
@@ -414,9 +374,7 @@ static int if_write_room(struct tty_struct *tty)
        if (!cs->connected) {
                gig_dbg(DEBUG_IF, "not connected");
                retval = -ENODEV;
-       } else if (!cs->open_count)
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
-       else if (cs->mstate != MS_LOCKED) {
+       } else if (cs->mstate != MS_LOCKED) {
                dev_warn(cs->dev, "can't write to unlocked device\n");
                retval = -EBUSY;
        } else
@@ -429,23 +387,15 @@ static int if_write_room(struct tty_struct *tty)
 
 static int if_chars_in_buffer(struct tty_struct *tty)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        int retval = 0;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return 0;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
        mutex_lock(&cs->mutex);
 
        if (!cs->connected)
                gig_dbg(DEBUG_IF, "not connected");
-       else if (!cs->open_count)
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
        else if (cs->mstate != MS_LOCKED)
                dev_warn(cs->dev, "can't write to unlocked device\n");
        else
@@ -458,13 +408,7 @@ static int if_chars_in_buffer(struct tty_struct *tty)
 
 static void if_throttle(struct tty_struct *tty)
 {
-       struct cardstate *cs;
-
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return;
-       }
+       struct cardstate *cs = tty->driver_data;
 
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
@@ -472,8 +416,6 @@ static void if_throttle(struct tty_struct *tty)
 
        if (!cs->connected)
                gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
-       else if (!cs->open_count)
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
        else
                gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);
 
@@ -482,13 +424,7 @@ static void if_throttle(struct tty_struct *tty)
 
 static void if_unthrottle(struct tty_struct *tty)
 {
-       struct cardstate *cs;
-
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return;
-       }
+       struct cardstate *cs = tty->driver_data;
 
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
@@ -496,8 +432,6 @@ static void if_unthrottle(struct tty_struct *tty)
 
        if (!cs->connected)
                gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
-       else if (!cs->open_count)
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
        else
                gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);
 
@@ -506,18 +440,12 @@ static void if_unthrottle(struct tty_struct *tty)
 
 static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
 {
-       struct cardstate *cs;
+       struct cardstate *cs = tty->driver_data;
        unsigned int iflag;
        unsigned int cflag;
        unsigned int old_cflag;
        unsigned int control_state, new_state;
 
-       cs = (struct cardstate *) tty->driver_data;
-       if (!cs) {
-               pr_err("%s: no cardstate\n", __func__);
-               return;
-       }
-
        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 
        mutex_lock(&cs->mutex);
@@ -527,11 +455,6 @@ static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
                goto out;
        }
 
-       if (!cs->open_count) {
-               dev_warn(cs->dev, "%s: device not opened\n", __func__);
-               goto out;
-       }
-
        iflag = tty->termios->c_iflag;
        cflag = tty->termios->c_cflag;
        old_cflag = old ? old->c_cflag : cflag;