TTY: ircomm, use tty from tty_port

This also includes a switch to tty refcounting. It makes sure, the
code no longer can access a freed TTY struct.

Sometimes the only thing needed is to pass tty down to the callies.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 70 insertions, 41 deletions

diff --git a/net/irda/ircomm/ircomm_param.c b/net/irda/ircomm/ircomm_param.c
index 8b915f3ac3b..30893912835 100644
--- a/net/irda/ircomm/ircomm_param.c
+++ b/net/irda/ircomm/ircomm_param.c
@@ -99,7 +99,6 @@ pi_param_info_t ircomm_param_info = { pi_major_call_table, 3, 0x0f, 4 };
  */
 int ircomm_param_request(struct ircomm_tty_cb *self, __u8 pi, int flush)
 {
-        struct tty_struct *tty;
         unsigned long flags;
         struct sk_buff *skb;
         int count;
@@ -109,10 +108,6 @@ int ircomm_param_request(struct ircomm_tty_cb *self, __u8 pi, int flush)
         IRDA_ASSERT(self != NULL, return -1;);
         IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);
 
-        tty = self->tty;
-        if (!tty)
-                return 0;
-
         /* Make sure we don't send parameters for raw mode */
         if (self->service_type == IRCOMM_3_WIRE_RAW)
                 return 0;
diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c
index 7b2152cfd42..03acc073b8c 100644
--- a/net/irda/ircomm/ircomm_tty.c
+++ b/net/irda/ircomm/ircomm_tty.c
@@ -242,18 +242,15 @@ err:
  *
  */
 static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
-                                      struct file *filp)
+                struct tty_struct *tty, struct file *filp)
 {
         DECLARE_WAITQUEUE(wait, current);
         int             retval;
         int             do_clocal = 0, extra_count = 0;
         unsigned long   flags;
-        struct tty_struct *tty;
 
         IRDA_DEBUG(2, "%s()\n", __func__ );
 
-        tty = self->tty;
-
         /*
          * If non-blocking mode is set, or the port is not enabled,
          * then make the check up front and then exit.
@@ -412,8 +409,8 @@ static int ircomm_tty_open(struct tty_struct *tty, struct file *filp)
         self->port.count++;
 
         tty->driver_data = self;
-        self->tty = tty;
         spin_unlock_irqrestore(&self->port.lock, flags);
+        tty_port_tty_set(&self->port, tty);
 
         IRDA_DEBUG(1, "%s(), %s%d, count = %d\n", __func__ , tty->driver->name,
                    self->line, self->port.count);
@@ -467,7 +464,7 @@ static int ircomm_tty_open(struct tty_struct *tty, struct file *filp)
         if (ret)
                 return ret;
 
-        ret = ircomm_tty_block_til_ready(self, filp);
+        ret = ircomm_tty_block_til_ready(self, tty, filp);
         if (ret) {
                 IRDA_DEBUG(2,
                       "%s(), returning after block_til_ready with %d\n", __func__ ,
@@ -548,7 +545,6 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
 
         spin_lock_irqsave(&self->port.lock, flags);
         tty->closing = 0;
-        self->tty = NULL;
 
         if (self->port.blocked_open) {
                 if (self->port.close_delay) {
@@ -562,6 +558,7 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
         self->port.flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING);
         spin_unlock_irqrestore(&self->port.lock, flags);
         wake_up_interruptible(&self->port.close_wait);
+        tty_port_tty_set(&self->port, NULL);
 }
 
 /*
@@ -604,7 +601,7 @@ static void ircomm_tty_do_softint(struct work_struct *work)
         if (!self || self->magic != IRCOMM_TTY_MAGIC)
                 return;
 
-        tty = self->tty;
+        tty = tty_port_tty_get(&self->port);
         if (!tty)
                 return;
 
@@ -625,7 +622,7 @@ static void ircomm_tty_do_softint(struct work_struct *work)
         }
 
         if (tty->hw_stopped)
-                return;
+                goto put;
 
         /* Unlink transmit buffer */
         spin_lock_irqsave(&self->spinlock, flags);
@@ -644,6 +641,8 @@ static void ircomm_tty_do_softint(struct work_struct *work)
 
         /* Check if user (still) wants to be waken up */
         tty_wakeup(tty);
+put:
+        tty_kref_put(tty);
 }
 
 /*
@@ -1004,7 +1003,11 @@ static void ircomm_tty_hangup(struct tty_struct *tty)
 
         spin_lock_irqsave(&self->port.lock, flags);
         self->port.flags &= ~ASYNC_NORMAL_ACTIVE;
-        self->tty = NULL;
+        if (self->port.tty) {
+                set_bit(TTY_IO_ERROR, &self->port.tty->flags);
+                tty_kref_put(self->port.tty);
+        }
+        self->port.tty = NULL;
         self->port.count = 0;
         spin_unlock_irqrestore(&self->port.lock, flags);
 
@@ -1068,7 +1071,7 @@ void ircomm_tty_check_modem_status(struct ircomm_tty_cb *self)
         IRDA_ASSERT(self != NULL, return;);
         IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
 
-        tty = self->tty;
+        tty = tty_port_tty_get(&self->port);
 
         status = self->settings.dce;
 
@@ -1089,10 +1092,10 @@ void ircomm_tty_check_modem_status(struct ircomm_tty_cb *self)
                                 tty_hangup(tty);
 
                         /* Hangup will remote the tty, so better break out */
-                        return;
+                        goto put;
                 }
         }
-        if (self->port.flags & ASYNC_CTS_FLOW) {
+        if (tty && self->port.flags & ASYNC_CTS_FLOW) {
                 if (tty->hw_stopped) {
                         if (status & IRCOMM_CTS) {
                                 IRDA_DEBUG(2,
@@ -1103,7 +1106,7 @@ void ircomm_tty_check_modem_status(struct ircomm_tty_cb *self)
                                 wake_up_interruptible(&self->port.open_wait);
 
                                 schedule_work(&self->tqueue);
-                                return;
+                                goto put;
                         }
                 } else {
                         if (!(status & IRCOMM_CTS)) {
@@ -1113,6 +1116,8 @@ void ircomm_tty_check_modem_status(struct ircomm_tty_cb *self)
                         }
                 }
         }
+put:
+        tty_kref_put(tty);
 }
 
 /*
@@ -1125,6 +1130,7 @@ static int ircomm_tty_data_indication(void *instance, void *sap,
                                       struct sk_buff *skb)
 {
         struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) instance;
+        struct tty_struct *tty;
 
         IRDA_DEBUG(2, "%s()\n", __func__ );
 
@@ -1132,7 +1138,8 @@ static int ircomm_tty_data_indication(void *instance, void *sap,
         IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);
         IRDA_ASSERT(skb != NULL, return -1;);
 
-        if (!self->tty) {
+        tty = tty_port_tty_get(&self->port);
+        if (!tty) {
                 IRDA_DEBUG(0, "%s(), no tty!\n", __func__ );
                 return 0;
         }
@@ -1143,7 +1150,7 @@ static int ircomm_tty_data_indication(void *instance, void *sap,
          * Devices like WinCE can do this, and since they don't send any
          * params, we can just as well declare the hardware for running.
          */
-        if (self->tty->hw_stopped && (self->flow == FLOW_START)) {
+        if (tty->hw_stopped && (self->flow == FLOW_START)) {
                 IRDA_DEBUG(0, "%s(), polling for line settings!\n", __func__ );
                 ircomm_param_request(self, IRCOMM_POLL, TRUE);
 
@@ -1156,8 +1163,9 @@ static int ircomm_tty_data_indication(void *instance, void *sap,
          * Use flip buffer functions since the code may be called from interrupt
          * context
          */
-        tty_insert_flip_string(self->tty, skb->data, skb->len);
-        tty_flip_buffer_push(self->tty);
+        tty_insert_flip_string(tty, skb->data, skb->len);
+        tty_flip_buffer_push(tty);
+        tty_kref_put(tty);
 
         /* No need to kfree_skb - see ircomm_ttp_data_indication() */
 
@@ -1208,12 +1216,13 @@ static void ircomm_tty_flow_indication(void *instance, void *sap,
         IRDA_ASSERT(self != NULL, return;);
         IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
 
-        tty = self->tty;
+        tty = tty_port_tty_get(&self->port);
 
         switch (cmd) {
         case FLOW_START:
                 IRDA_DEBUG(2, "%s(), hw start!\n", __func__ );
-                tty->hw_stopped = 0;
+                if (tty)
+                        tty->hw_stopped = 0;
 
                 /* ircomm_tty_do_softint will take care of the rest */
                 schedule_work(&self->tqueue);
@@ -1221,15 +1230,19 @@ static void ircomm_tty_flow_indication(void *instance, void *sap,
         default:  /* If we get here, something is very wrong, better stop */
         case FLOW_STOP:
                 IRDA_DEBUG(2, "%s(), hw stopped!\n", __func__ );
-                tty->hw_stopped = 1;
+                if (tty)
+                        tty->hw_stopped = 1;
                 break;
         }
+
+        tty_kref_put(tty);
         self->flow = cmd;
 }
 
 #ifdef CONFIG_PROC_FS
 static void ircomm_tty_line_info(struct ircomm_tty_cb *self, struct seq_file *m)
 {
+        struct tty_struct *tty;
         char sep;
 
         seq_printf(m, "State: %s\n", ircomm_tty_state[self->state]);
@@ -1356,9 +1369,12 @@ static void ircomm_tty_line_info(struct ircomm_tty_cb *self, struct seq_file *m)
         seq_printf(m, "Max data size: %d\n", self->max_data_size);
         seq_printf(m, "Max header size: %d\n", self->max_header_size);
 
-        if (self->tty)
+        tty = tty_port_tty_get(&self->port);
+        if (tty) {
                 seq_printf(m, "Hardware: %s\n",
-                               self->tty->hw_stopped ? "Stopped" : "Running");
+                               tty->hw_stopped ? "Stopped" : "Running");
+                tty_kref_put(tty);
+        }
 }
 
 static int ircomm_tty_proc_show(struct seq_file *m, void *v)
diff --git a/net/irda/ircomm/ircomm_tty_attach.c b/net/irda/ircomm/ircomm_tty_attach.c
index bed311af731..3ab70e7a071 100644
--- a/net/irda/ircomm/ircomm_tty_attach.c
+++ b/net/irda/ircomm/ircomm_tty_attach.c
@@ -130,6 +130,8 @@ static int (*state[])(struct ircomm_tty_cb *self, IRCOMM_TTY_EVENT event,
  */
 int ircomm_tty_attach_cable(struct ircomm_tty_cb *self)
 {
+        struct tty_struct *tty;
+
         IRDA_DEBUG(0, "%s()\n", __func__ );
 
         IRDA_ASSERT(self != NULL, return -1;);
@@ -142,7 +144,11 @@ int ircomm_tty_attach_cable(struct ircomm_tty_cb *self)
         }
 
         /* Make sure nobody tries to write before the link is up */
-        self->tty->hw_stopped = 1;
+        tty = tty_port_tty_get(&self->port);
+        if (tty) {
+                tty->hw_stopped = 1;
+                tty_kref_put(tty);
+        }
 
         ircomm_tty_ias_register(self);
 
@@ -398,23 +404,26 @@ void ircomm_tty_disconnect_indication(void *instance, void *sap,
                                       struct sk_buff *skb)
 {
         struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) instance;
+        struct tty_struct *tty;
 
         IRDA_DEBUG(2, "%s()\n", __func__ );
 
         IRDA_ASSERT(self != NULL, return;);
         IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
 
-        if (!self->tty)
+        tty = tty_port_tty_get(&self->port);
+        if (!tty)
                 return;
 
         /* This will stop control data transfers */
         self->flow = FLOW_STOP;
 
         /* Stop data transfers */
-        self->tty->hw_stopped = 1;
+        tty->hw_stopped = 1;
 
         ircomm_tty_do_event(self, IRCOMM_TTY_DISCONNECT_INDICATION, NULL,
                             NULL);
+        tty_kref_put(tty);
 }
 
 /*
@@ -550,12 +559,15 @@ void ircomm_tty_connect_indication(void *instance, void *sap,
  */
 void ircomm_tty_link_established(struct ircomm_tty_cb *self)
 {
+        struct tty_struct *tty;
+
         IRDA_DEBUG(2, "%s()\n", __func__ );
 
         IRDA_ASSERT(self != NULL, return;);
         IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
 
-        if (!self->tty)
+        tty = tty_port_tty_get(&self->port);
+        if (!tty)
                 return;
 
         del_timer(&self->watchdog_timer);
@@ -569,17 +581,19 @@ void ircomm_tty_link_established(struct ircomm_tty_cb *self)
         if ((self->port.flags & ASYNC_CTS_FLOW) &&
                         ((self->settings.dce & IRCOMM_CTS) == 0)) {
                 IRDA_DEBUG(0, "%s(), waiting for CTS ...\n", __func__ );
-                return;
+                goto put;
         } else {
                 IRDA_DEBUG(1, "%s(), starting hardware!\n", __func__ );
 
-                self->tty->hw_stopped = 0;
+                tty->hw_stopped = 0;
 
                 /* Wake up processes blocked on open */
                 wake_up_interruptible(&self->port.open_wait);
         }
 
         schedule_work(&self->tqueue);
+put:
+        tty_kref_put(tty);
 }
 
 /*
@@ -983,9 +997,12 @@ static int ircomm_tty_state_ready(struct ircomm_tty_cb *self,
                         self->settings.dce = IRCOMM_DELTA_CD;
                         ircomm_tty_check_modem_status(self);
                 } else {
+                        struct tty_struct *tty = tty_port_tty_get(&self->port);
                         IRDA_DEBUG(0, "%s(), hanging up!\n", __func__ );
-                        if (self->tty)
-                                tty_hangup(self->tty);
+                        if (tty) {
+                                tty_hangup(tty);
+                                tty_kref_put(tty);
+                        }
                 }
                 break;
         default:
diff --git a/net/irda/ircomm/ircomm_tty_ioctl.c b/net/irda/ircomm/ircomm_tty_ioctl.c
index 31b917e9c8d..0eab6500e99 100644
--- a/net/irda/ircomm/ircomm_tty_ioctl.c
+++ b/net/irda/ircomm/ircomm_tty_ioctl.c
@@ -52,17 +52,18 @@
  *    Change speed of the driver. If the remote device is a DCE, then this
  *    should make it change the speed of its serial port
  */
-static void ircomm_tty_change_speed(struct ircomm_tty_cb *self)
+static void ircomm_tty_change_speed(struct ircomm_tty_cb *self,
+                struct tty_struct *tty)
 {
         unsigned int cflag, cval;
         int baud;
 
         IRDA_DEBUG(2, "%s()\n", __func__ );
 
-        if (!self->tty || !self->tty->termios || !self->ircomm)
+        if (!self->ircomm)
                 return;
 
-        cflag = self->tty->termios->c_cflag;
+        cflag = tty->termios->c_cflag;
 
         /*  byte size and parity */
         switch (cflag & CSIZE) {
@@ -81,7 +82,7 @@ static void ircomm_tty_change_speed(struct ircomm_tty_cb *self)
                 cval |= IRCOMM_PARITY_EVEN;
 
         /* Determine divisor based on baud rate */
-        baud = tty_get_baud_rate(self->tty);
+        baud = tty_get_baud_rate(tty);
         if (!baud)
                 baud = 9600;    /* B0 transition handled in rs_set_termios */
 
@@ -159,7 +160,7 @@ void ircomm_tty_set_termios(struct tty_struct *tty,
                 return;
         }
 
-        ircomm_tty_change_speed(self);
+        ircomm_tty_change_speed(self, tty);
 
         /* Handle transition to B0 status */
         if ((old_termios->c_cflag & CBAUD) &&