[IA64] Fix registered interrupt check

Fix the problem that interrupts are not initialized correctly at PCI
hotplug or driver reloading time.

By vector domain change, the iosapic_rte_info structure was changed to
be on the iosapic_intr_info[irq].rtes list even after the interrupts
are unregistered. So iosapic_intr_info[irq].rtes list must not be
checked to see if there are registered interrupts (RTEs) on the
irq. We must check iosapic_intr_info[irq].count counter instead.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/iosapic.c

@@ -142,7 +142,7 @@ struct iosapic_rte_info {
 static struct iosapic_intr_info {
 	struct list_head rtes;		/* RTEs using this vector (empty =>
 					 * not an IOSAPIC interrupt) */
-	int		count;		/* # of RTEs that shares this vector */
+	int		count;		/* # of registered RTEs */
 	u32		low32;		/* current value of low word of
 					 * Redirection table entry */
 	unsigned int	dest;		/* destination CPU physical ID */
@@ -313,7 +313,7 @@ mask_irq (unsigned int irq)
 	int rte_index;
 	struct iosapic_rte_info *rte;
 
-	if (list_empty(&iosapic_intr_info[irq].rtes))
+	if (!iosapic_intr_info[irq].count)
 		return;			/* not an IOSAPIC interrupt! */
 
 	/* set only the mask bit */
@@ -331,7 +331,7 @@ unmask_irq (unsigned int irq)
 	int rte_index;
 	struct iosapic_rte_info *rte;
 
-	if (list_empty(&iosapic_intr_info[irq].rtes))
+	if (!iosapic_intr_info[irq].count)
 		return;			/* not an IOSAPIC interrupt! */
 
 	low32 = iosapic_intr_info[irq].low32 &= ~IOSAPIC_MASK;
@@ -363,7 +363,7 @@ iosapic_set_affinity (unsigned int irq, cpumask_t mask)
 
 	dest = cpu_physical_id(first_cpu(mask));
 
-	if (list_empty(&iosapic_intr_info[irq].rtes))
+	if (!iosapic_intr_info[irq].count)
 		return;			/* not an IOSAPIC interrupt */
 
 	set_irq_affinity_info(irq, dest, redir);
@@ -542,7 +542,7 @@ iosapic_reassign_vector (int irq)
 {
 	int new_irq;
 
-	if (!list_empty(&iosapic_intr_info[irq].rtes)) {
+	if (iosapic_intr_info[irq].count) {
 		new_irq = create_irq();
 		if (new_irq < 0)
 			panic("%s: out of interrupt vectors!\n", __FUNCTION__);
@@ -677,7 +677,7 @@ get_target_cpu (unsigned int gsi, int irq)
 	 * In case of vector shared by multiple RTEs, all RTEs that
 	 * share the vector need to use the same destination CPU.
 	 */
-	if (!list_empty(&iosapic_intr_info[irq].rtes))
+	if (iosapic_intr_info[irq].count)
 		return iosapic_intr_info[irq].dest;
 
 	/*