irqdomain: Fix driver re-inserting failures when IRQs not being freed

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GNIE

------------------------------------------------------------------------

Since commit 4615fbc3 ("genirq/irqdomain: Don't try to free an
interrupt that has no mapping"), we have found failures when
re-inserting some specific drivers:

[root@localhost ~]# rmmod hisi_sas_v3_hw
[root@localhost ~]# modprobe hisi_sas_v3_hw
[ 1295.622525] hisi_sas_v3_hw: probe of 0000:30:04.0 failed with error -2

A relevant discussion can be found at:
https://lore.kernel.org/lkml/3d3d0155e66429968cb4f6b4feeae4b3@kernel.org/

This is because IRQs from a low-level domain are not freed together,
leaving some leaked. Thus, the next driver insertion fails to allocate
the same number of IRQs.

Free a contiguous group of IRQs in one go to fix this issue.

Fixes: 4615fbc3 ("genirq/irqdomain: Don't try to free an interrupt
that has no mapping")
Signed-off-by: NJie Zhan <zhanjie9@hisilicon.com>
Reviewed-by: NLiao Chang <liaochang1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/irq/irqdomain.c

@@ -1374,13 +1374,24 @@ static void irq_domain_free_irqs_hierarchy(struct irq_domain *domain,
 					   unsigned int nr_irqs)
 {
 	unsigned int i;
+	int n;
 
 	if (!domain->ops->free)
 		return;
 
 	for (i = 0; i < nr_irqs; i++) {
-		if (irq_domain_get_irq_data(domain, irq_base + i))
-			domain->ops->free(domain, irq_base + i, 1);
+		/* Find the largest possible span of IRQs to free in one go */
+		for (n = 0;
+			((i + n) < nr_irqs) &&
+			 (irq_domain_get_irq_data(domain, irq_base + i + n));
+			n++)
+			;
+
+		if (!n)
+			continue;
+
+		domain->ops->free(domain, irq_base + i, n);
+		i += n;
 	}
 }