tty: relock epca

Bring epca into line with the port locking.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 104 insertions, 91 deletions

diff --git a/drivers/char/epca.c b/drivers/char/epca.c
index da2d2cf16f5..e07d7925c30 100644
--- a/drivers/char/epca.c
+++ b/drivers/char/epca.c
@@ -69,7 +69,9 @@ static int invalid_lilo_config;
 
 /*
  * The ISA boards do window flipping into the same spaces so its only sane with
- * a single lock. It's still pretty efficient.
+ * a single lock. It's still pretty efficient. This lock guards the hardware
+ * and the tty_port lock guards the kernel side stuff like use counts. Take
+ * this lock inside the port lock if you must take both.
  */
 static DEFINE_SPINLOCK(epca_lock);
 
@@ -156,7 +158,7 @@ static struct channel *verifyChannel(struct tty_struct *);
 static void pc_sched_event(struct channel *, int);
 static void epca_error(int, char *);
 static void pc_close(struct tty_struct *, struct file *);
-static void shutdown(struct channel *);
+static void shutdown(struct channel *, struct tty_struct *tty);
 static void pc_hangup(struct tty_struct *);
 static int pc_write_room(struct tty_struct *);
 static int pc_chars_in_buffer(struct tty_struct *);
@@ -419,76 +421,78 @@ static void epca_error(int line, char *msg)
 static void pc_close(struct tty_struct *tty, struct file *filp)
 {
         struct channel *ch;
+        struct tty_port *port;
         unsigned long flags;
         /*
          * verifyChannel returns the channel from the tty struct if it is
          * valid. This serves as a sanity check.
          */
         ch = verifyChannel(tty);
-        if (ch != NULL) {
-                spin_lock_irqsave(&epca_lock, flags);
-                if (tty_hung_up_p(filp)) {
-                        spin_unlock_irqrestore(&epca_lock, flags);
-                        return;
-                }
-                if (ch->port.count-- > 1)  {
-                        /* Begin channel is open more than once */
-                        /*
-                         * Return without doing anything. Someone might still
-                         * be using the channel.
-                         */
-                        spin_unlock_irqrestore(&epca_lock, flags);
-                        return;
-                }
-                /* Port open only once go ahead with shutdown & reset */
-                BUG_ON(ch->port.count < 0);
+        if (ch == NULL)
+                return;
+        port = &ch->port;
 
+        spin_lock_irqsave(&port->lock, flags);
+        if (tty_hung_up_p(filp)) {
+                spin_unlock_irqrestore(&port->lock, flags);
+                return;
+        }
+        if (port->count-- > 1)  {
+                /* Begin channel is open more than once */
                 /*
-                 * Let the rest of the driver know the channel is being closed.
-                 * This becomes important if an open is attempted before close
-                 * is finished.
+                 * Return without doing anything. Someone might still
+                 * be using the channel.
                  */
-                ch->port.flags |= ASYNC_CLOSING;
-                tty->closing = 1;
-
-                spin_unlock_irqrestore(&epca_lock, flags);
-
-                if (ch->port.flags & ASYNC_INITIALIZED)  {
-                        /* Setup an event to indicate when the
-                           transmit buffer empties */
-                        setup_empty_event(tty, ch);
-                        /* 30 seconds timeout */
-                        tty_wait_until_sent(tty, 3000);
-                }
-                pc_flush_buffer(tty);
+                spin_unlock_irqrestore(&port->lock, flags);
+                return;
+        }
+        /* Port open only once go ahead with shutdown & reset */
+        WARN_ON(port->count < 0);
 
-                tty_ldisc_flush(tty);
-                shutdown(ch);
+        /*
+         * Let the rest of the driver know the channel is being closed.
+         * This becomes important if an open is attempted before close
+         * is finished.
+         */
+        port->flags |= ASYNC_CLOSING;
+        tty->closing = 1;
 
-                spin_lock_irqsave(&epca_lock, flags);
-                tty->closing = 0;
-                ch->event = 0;
-                ch->port.tty = NULL;
-                spin_unlock_irqrestore(&epca_lock, flags);
+        spin_unlock_irqrestore(&port->lock, flags);
 
-                if (ch->port.blocked_open) {
-                        if (ch->close_delay)
-                                msleep_interruptible(jiffies_to_msecs(ch->close_delay));
-                        wake_up_interruptible(&ch->port.open_wait);
-                }
-                ch->port.flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED |
-                                        ASYNC_CLOSING);
-                wake_up_interruptible(&ch->port.close_wait);
+        if (port->flags & ASYNC_INITIALIZED)  {
+                /* Setup an event to indicate when the
+                   transmit buffer empties */
+                setup_empty_event(tty, ch);
+                /* 30 seconds timeout */
+                tty_wait_until_sent(tty, 3000);
+        }
+        pc_flush_buffer(tty);
+        tty_ldisc_flush(tty);
+        shutdown(ch, tty);
+
+        spin_lock_irqsave(&port->lock, flags);
+        tty->closing = 0;
+        ch->event = 0;
+        port->tty = NULL;
+        spin_unlock_irqrestore(&port->lock, flags);
+
+        if (port->blocked_open) {
+                if (ch->close_delay)
+                        msleep_interruptible(jiffies_to_msecs(ch->close_delay));
+                wake_up_interruptible(&port->open_wait);
         }
+        port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED |
+                                                        ASYNC_CLOSING);
+        wake_up_interruptible(&port->close_wait);
 }
 
-static void shutdown(struct channel *ch)
+static void shutdown(struct channel *ch, struct tty_struct *tty)
 {
         unsigned long flags;
-        struct tty_struct *tty;
         struct board_chan __iomem *bc;
+        struct tty_port *port = &ch->port;
 
-        if (!(ch->port.flags & ASYNC_INITIALIZED))
+        if (!(port->flags & ASYNC_INITIALIZED))
                 return;
 
         spin_lock_irqsave(&epca_lock, flags);
@@ -503,7 +507,6 @@ static void shutdown(struct channel *ch)
          */
         if (bc)
                 writeb(0, &bc->idata);
-        tty = ch->port.tty;
 
         /* If we're a modem control device and HUPCL is on, drop RTS & DTR. */
         if (tty->termios->c_cflag & HUPCL)  {
@@ -517,13 +520,15 @@ static void shutdown(struct channel *ch)
          * will have to reinitialized. Set a flag to indicate this.
          */
         /* Prevent future Digi programmed interrupts from coming active */
-        ch->port.flags &= ~ASYNC_INITIALIZED;
+        port->flags &= ~ASYNC_INITIALIZED;
         spin_unlock_irqrestore(&epca_lock, flags);
 }
 
 static void pc_hangup(struct tty_struct *tty)
 {
         struct channel *ch;
+        struct tty_port *port;
+
         /*
          * verifyChannel returns the channel from the tty struct if it is
          * valid. This serves as a sanity check.
@@ -531,18 +536,19 @@ static void pc_hangup(struct tty_struct *tty)
         ch = verifyChannel(tty);
         if (ch != NULL) {
                 unsigned long flags;
+                port = &ch->port;
 
                 pc_flush_buffer(tty);
                 tty_ldisc_flush(tty);
-                shutdown(ch);
-
-                spin_lock_irqsave(&epca_lock, flags);
-                ch->port.tty   = NULL;
-                ch->event = 0;
-                ch->port.count = 0;
-                ch->port.flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED);
-                spin_unlock_irqrestore(&epca_lock, flags);
-                wake_up_interruptible(&ch->port.open_wait);
+                shutdown(ch, tty);
+
+                spin_lock_irqsave(&port->lock, flags);
+                port->tty = NULL;
+                ch->event = 0;  /* FIXME: review locking of ch->event */
+                port->count = 0;
+                port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED);
+                spin_unlock_irqrestore(&port->lock, flags);
+                wake_up_interruptible(&port->open_wait);
         }
 }
 
@@ -792,9 +798,10 @@ static int block_til_ready(struct tty_struct *tty,
         DECLARE_WAITQUEUE(wait, current);
         int retval, do_clocal = 0;
         unsigned long flags;
+        struct tty_port *port = &ch->port;
 
         if (tty_hung_up_p(filp)) {
-                if (ch->port.flags & ASYNC_HUP_NOTIFY)
+                if (port->flags & ASYNC_HUP_NOTIFY)
                         retval = -EAGAIN;
                 else
                         retval = -ERESTARTSYS;
@@ -805,10 +812,10 @@ static int block_til_ready(struct tty_struct *tty,
          * If the device is in the middle of being closed, then block until
          * it's done, and then try again.
          */
-        if (ch->port.flags & ASYNC_CLOSING) {
-                interruptible_sleep_on(&ch->port.close_wait);
+        if (port->flags & ASYNC_CLOSING) {
+                interruptible_sleep_on(&port->close_wait);
 
-                if (ch->port.flags & ASYNC_HUP_NOTIFY)
+                if (port->flags & ASYNC_HUP_NOTIFY)
                         return -EAGAIN;
                 else
                         return -ERESTARTSYS;
@@ -819,7 +826,7 @@ static int block_til_ready(struct tty_struct *tty,
                  * If non-blocking mode is set, then make the check up front
                  * and then exit.
                  */
-                ch->port.flags |= ASYNC_NORMAL_ACTIVE;
+                port->flags |= ASYNC_NORMAL_ACTIVE;
                 return 0;
         }
         if (tty->termios->c_cflag & CLOCAL)
@@ -827,31 +834,31 @@ static int block_til_ready(struct tty_struct *tty,
         /* Block waiting for the carrier detect and the line to become free */
 
         retval = 0;
-        add_wait_queue(&ch->port.open_wait, &wait);
+        add_wait_queue(&port->open_wait, &wait);
 
-        spin_lock_irqsave(&epca_lock, flags);
+        spin_lock_irqsave(&port->lock, flags);
         /* We dec count so that pc_close will know when to free things */
         if (!tty_hung_up_p(filp))
-                ch->port.count--;
-        ch->port.blocked_open++;
+                port->count--;
+        port->blocked_open++;
         while (1) {
                 set_current_state(TASK_INTERRUPTIBLE);
                 if (tty_hung_up_p(filp) ||
-                                !(ch->port.flags & ASYNC_INITIALIZED)) {
-                        if (ch->port.flags & ASYNC_HUP_NOTIFY)
+                                !(port->flags & ASYNC_INITIALIZED)) {
+                        if (port->flags & ASYNC_HUP_NOTIFY)
                                 retval = -EAGAIN;
                         else
                                 retval = -ERESTARTSYS;
                         break;
                 }
-                if (!(ch->port.flags & ASYNC_CLOSING) &&
+                if (!(port->flags & ASYNC_CLOSING) &&
                           (do_clocal || (ch->imodem & ch->dcd)))
                         break;
                 if (signal_pending(current)) {
                         retval = -ERESTARTSYS;
                         break;
                 }
-                spin_unlock_irqrestore(&epca_lock, flags);
+                spin_unlock_irqrestore(&port->lock, flags);
                 /*
                  * Allow someone else to be scheduled. We will occasionally go
                  * through this loop until one of the above conditions change.
@@ -859,27 +866,28 @@ static int block_til_ready(struct tty_struct *tty,
                  * and prevent this loop from hogging the cpu.
                  */
                 schedule();
-                spin_lock_irqsave(&epca_lock, flags);
+                spin_lock_irqsave(&port->lock, flags);
         }
 
         __set_current_state(TASK_RUNNING);
-        remove_wait_queue(&ch->port.open_wait, &wait);
+        remove_wait_queue(&port->open_wait, &wait);
         if (!tty_hung_up_p(filp))
-                ch->port.count++;
-        ch->port.blocked_open--;
+                port->count++;
+        port->blocked_open--;
 
-        spin_unlock_irqrestore(&epca_lock, flags);
+        spin_unlock_irqrestore(&port->lock, flags);
 
         if (retval)
                 return retval;
 
-        ch->port.flags |= ASYNC_NORMAL_ACTIVE;
+        port->flags |= ASYNC_NORMAL_ACTIVE;
         return 0;
 }
 
 static int pc_open(struct tty_struct *tty, struct file *filp)
 {
         struct channel *ch;
+        struct tty_port *port;
         unsigned long flags;
         int line, retval, boardnum;
         struct board_chan __iomem *bc;
@@ -890,6 +898,7 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
                 return -ENODEV;
 
         ch = &digi_channels[line];
+        port = &ch->port;
         boardnum = ch->boardnum;
 
         /* Check status of board configured in system.  */
@@ -926,22 +935,24 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
                 return -ENODEV;
         }
 
-        spin_lock_irqsave(&epca_lock, flags);
+        spin_lock_irqsave(&port->lock, flags);
         /*
          * Every time a channel is opened, increment a counter. This is
          * necessary because we do not wish to flush and shutdown the channel
          * until the last app holding the channel open, closes it.
          */
-        ch->port.count++;
+        port->count++;
         /*
          * Set a kernel structures pointer to our local channel structure. This
          * way we can get to it when passed only a tty struct.
          */
         tty->driver_data = ch;
+        port->tty = tty;
         /*
          * If this is the first time the channel has been opened, initialize
          * the tty->termios struct otherwise let pc_close handle it.
          */
+        spin_lock(&epca_lock);
         globalwinon(ch);
         ch->statusflags = 0;
 
@@ -956,16 +967,16 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
         writew(head, &bc->rout);
 
         /* Set the channels associated tty structure */
-        ch->port.tty = tty;
 
         /*
          * The below routine generally sets up parity, baud, flow control
          * issues, etc.... It effect both control flags and input flags.
          */
         epcaparam(tty, ch);
-        ch->port.flags |= ASYNC_INITIALIZED;
         memoff(ch);
-        spin_unlock_irqrestore(&epca_lock, flags);
+        spin_unlock(&epca_lock);
+        port->flags |= ASYNC_INITIALIZED;
+        spin_unlock_irqrestore(&port->lock, flags);
 
         retval = block_til_ready(tty, filp, ch);
         if (retval)
@@ -974,13 +985,15 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
          * Set this again in case a hangup set it to zero while this open() was
          * waiting for the line...
          */
-        spin_lock_irqsave(&epca_lock, flags);
-        ch->port.tty = tty;
+        spin_lock_irqsave(&port->lock, flags);
+        port->tty = tty;
+        spin_lock(&epca_lock);
         globalwinon(ch);
         /* Enable Digi Data events */
         writeb(1, &bc->idata);
         memoff(ch);
-        spin_unlock_irqrestore(&epca_lock, flags);
+        spin_unlock(&epca_lock);
+        spin_unlock_irqrestore(&port->lock, flags);
         return 0;
 }