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Subject[PATCH 67/68] TTY: isdn/gigaset, do not set tty->driver_data to NULL
Date
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
---
drivers/isdn/gigaset/interface.c | 105 +++++---------------------------------
1 file changed, 14 insertions(+), 91 deletions(-)

diff --git a/drivers/isdn/gigaset/interface.c b/drivers/isdn/gigaset/interface.c
index 7e54577..040f5f9 100644
--- 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;
--
1.7.9.2



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