[PATCH] i2c-elektor: get rid of cli/sti

this patch get rid of cli()/sti(). while correcting this I found
that when a process wakes by an interrupt, pcf_pending doesn't
come back to 0 and next caller will return imediately. also,
there are other drivers with the exact same problem. if you
don't have any comments on this, I'll do the same for other
drivers.


[I2C] i2c-elektor: getting rid of cli()/sti() usage
Signed-off-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/i2c/busses/i2c-elektor.c

@@ -59,6 +59,7 @@ static int mmapped;
 
 static wait_queue_head_t pcf_wait;
 static int pcf_pending;
+static spinlock_t lock;
 
 /* ----- local functions ----------------------------------------------	*/
 
@@ -111,14 +112,24 @@ static int pcf_isa_getclock(void *data)
 static void pcf_isa_waitforpin(void) {
 
 	int timeout = 2;
+	long flags;
 
 	if (irq > 0) {
-		cli();
+		spin_lock_irqsave(&lock, flags);
 		if (pcf_pending == 0) {
-			interruptible_sleep_on_timeout(&pcf_wait, timeout*HZ );
-		} else
+			spin_unlock_irqrestore(&lock, flags);
+			if (interruptible_sleep_on_timeout(&pcf_wait,
+								timeout*HZ)) {
+				spin_lock_irqsave(&lock, flags);
+				if (pcf_pending == 1) {
+					pcf_pending = 0;
+				}
+				spin_unlock_irqrestore(&lock, flags);
+			}
+		} else {
 			pcf_pending = 0;
-		sti();
+			spin_unlock_irqrestore(&lock, flags);
+		}
 	} else {
 		udelay(100);
 	}
@@ -126,7 +137,9 @@ static void pcf_isa_waitforpin(void) {
 
 
 static irqreturn_t pcf_isa_handler(int this_irq, void *dev_id, struct pt_regs *regs) {
+	spin_lock(&lock);
 	pcf_pending = 1;
+	spin_unlock(&lock);
 	wake_up_interruptible(&pcf_wait);
 	return IRQ_HANDLED;
 }
@@ -134,6 +147,7 @@ static irqreturn_t pcf_isa_handler(int this_irq, void *dev_id, struct pt_regs *r
 
 static int pcf_isa_init(void)
 {
+	spin_lock_init(&lock);
 	if (!mmapped) {
 		if (!request_region(base, 2, "i2c (isa bus adapter)")) {
 			printk(KERN_ERR