Re: 2.6.12-rc1-mm3

[Dmitry Torokhov <dtor_core@ameritech.net>]

On Monday 28 March 2005 06:02, Russell King wrote:
> Looks like something in the input layer went bang.  The code in
> serport_ldisc_write_wakeup is:
> 
>    0:   8b 80 a8 09 00 00       mov    0x9a8(%eax),%eax
>    6:   8b 40 14                mov    0x14(%eax),%eax
>    9:   8b 50 70                mov    0x70(%eax),%edx <====
>    c:   85 d2                   test   %edx,%edx
>    e:   74 09                   je     0x19
> 
> and the marked line exploded on you.  The above instructions correspond
> with:
> 
> 0:      struct serport *sp = (struct serport *) tty->disc_data;
> 6:      serio_drv_write_wakeup(sp->serio);
> 9:      if (serio->drv
> 
> So, "serio" was this strange 0xf3a6cdf8 value.  But why?  One for the
> input people I think.

Reuben, could you please try the patch below? Thanks!

Russell, could you please tell me if ldisc->write_wakeup (tty_wakwup) and
ldisc->read are allowed to be called from an IRQ context? IOW I wonder if
I can use spil_lock_bh instead of spil_lock_irqsave to protect serport
flags.

-- 
Dmitry

 serport.c |   98 +++++++++++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 68 insertions(+), 30 deletions(-)

Index: dtor/drivers/input/serio/serport.c
===================================================================
--- dtor.orig/drivers/input/serio/serport.c
+++ dtor/drivers/input/serio/serport.c
@@ -27,11 +27,15 @@ MODULE_LICENSE("GPL");
 MODULE_ALIAS_LDISC(N_MOUSE);
 
 #define SERPORT_BUSY	1
+#define SERPORT_ACTIVE	2
+#define SERPORT_DEAD	3
 
 struct serport {
 	struct tty_struct *tty;
 	wait_queue_head_t wait;
 	struct serio *serio;
+	struct serio_device_id id;
+	spinlock_t lock;
 	unsigned long flags;
 };
 
@@ -45,11 +49,29 @@ static int serport_serio_write(struct se
 	return -(serport->tty->driver->write(serport->tty, &data, 1) != 1);
 }
 
+static int serport_serio_open(struct serio *serio)
+{
+	struct serport *serport = serio->port_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&serport->lock, flags);
+	set_bit(SERPORT_ACTIVE, &serport->flags);
+	spin_unlock_irqrestore(&serport->lock, flags);
+
+	return 0;
+}
+
+
 static void serport_serio_close(struct serio *serio)
 {
 	struct serport *serport = serio->port_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&serport->lock, flags);
+	clear_bit(SERPORT_ACTIVE, &serport->flags);
+	set_bit(SERPORT_DEAD, &serport->flags);
+	spin_unlock_irqrestore(&serport->lock, flags);
 
-	serport->serio->id.type = 0;
 	wake_up_interruptible(&serport->wait);
 }
 
@@ -61,36 +83,21 @@ static void serport_serio_close(struct s
 static int serport_ldisc_open(struct tty_struct *tty)
 {
 	struct serport *serport;
-	struct serio *serio;
-	char name[64];
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	serport = kmalloc(sizeof(struct serport), GFP_KERNEL);
-	serio = kmalloc(sizeof(struct serio), GFP_KERNEL);
-	if (unlikely(!serport || !serio)) {
-		kfree(serport);
-		kfree(serio);
+	serport = kcalloc(1, sizeof(struct serport), GFP_KERNEL);
+	if (!serport)
 		return -ENOMEM;
-	}
 
-	memset(serport, 0, sizeof(struct serport));
-	serport->serio = serio;
-	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 	serport->tty = tty;
-	tty->disc_data = serport;
-
-	memset(serio, 0, sizeof(struct serio));
-	strlcpy(serio->name, "Serial port", sizeof(serio->name));
-	snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
-	serio->id.type = SERIO_RS232;
-	serio->write = serport_serio_write;
-	serio->close = serport_serio_close;
-	serio->port_data = serport;
-
+	spin_lock_init(&serport->lock);
 	init_waitqueue_head(&serport->wait);
 
+	tty->disc_data = serport;
+	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+
 	return 0;
 }
 
@@ -100,7 +107,8 @@ static int serport_ldisc_open(struct tty
 
 static void serport_ldisc_close(struct tty_struct *tty)
 {
-	struct serport *serport = (struct serport*) tty->disc_data;
+	struct serport *serport = (struct serport *) tty->disc_data;
+
 	kfree(serport);
 }
 
@@ -116,9 +124,19 @@ static void serport_ldisc_close(struct t
 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
 {
 	struct serport *serport = (struct serport*) tty->disc_data;
+	unsigned long flags;
 	int i;
+
+	spin_lock_irqsave(&serport->lock, flags);
+
+	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
+		goto out;
+
 	for (i = 0; i < count; i++)
 		serio_interrupt(serport->serio, cp[i], 0, NULL);
+
+out:
+	spin_unlock_irqrestore(&serport->lock, flags);
 }
 
 /*
@@ -141,16 +159,33 @@ static int serport_ldisc_room(struct tty
 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
 {
 	struct serport *serport = (struct serport*) tty->disc_data;
+	struct serio *serio;
 	char name[64];
 
 	if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
 		return -EBUSY;
 
+	serport->serio = serio = kcalloc(1, sizeof(struct serio), GFP_KERNEL);
+	if (!serio)
+		return -ENOMEM;
+
+	strlcpy(serio->name, "Serial port", sizeof(serio->name));
+	snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
+	serio->id = serport->id;
+	serio->id.type = SERIO_RS232;
+	serio->write = serport_serio_write;
+	serio->open = serport_serio_open;
+	serio->close = serport_serio_close;
+	serio->port_data = serport;
+
 	serio_register_port(serport->serio);
 	printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name));
-	wait_event_interruptible(serport->wait, !serport->serio->id.type);
+
+	wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
 	serio_unregister_port(serport->serio);
+	serport->serio = NULL;
 
+	clear_bit(SERPORT_DEAD, &serport->flags);
 	clear_bit(SERPORT_BUSY, &serport->flags);
 
 	return 0;
@@ -163,16 +198,15 @@ static ssize_t serport_ldisc_read(struct
 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
 {
 	struct serport *serport = (struct serport*) tty->disc_data;
-	struct serio *serio = serport->serio;
 	unsigned long type;
 
 	if (cmd == SPIOCSTYPE) {
 		if (get_user(type, (unsigned long __user *) arg))
 			return -EFAULT;
 
-		serio->id.proto	= type & 0x000000ff;
-		serio->id.id	= (type & 0x0000ff00) >> 8;
-		serio->id.extra	= (type & 0x00ff0000) >> 16;
+		serport->id.proto = type & 0x000000ff;
+		serport->id.id	  = (type & 0x0000ff00) >> 8;
+		serport->id.extra = (type & 0x00ff0000) >> 16;
 
 		return 0;
 	}
@@ -182,9 +216,13 @@ static int serport_ldisc_ioctl(struct tt
 
 static void serport_ldisc_write_wakeup(struct tty_struct * tty)
 {
-	struct serport *sp = (struct serport *) tty->disc_data;
+	struct serport *serport = (struct serport *) tty->disc_data;
+	unsigned long flags;
 
-	serio_drv_write_wakeup(sp->serio);
+	spin_lock_irqsave(&serport->lock, flags);
+	if (test_bit(SERPORT_ACTIVE, &serport->flags))
+		serio_drv_write_wakeup(serport->serio);
+	spin_unlock_irqrestore(&serport->lock, flags);
 }
 
 /*