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Commit ed4dea6e authored by Yinghai Lu's avatar Yinghai Lu Committed by Thomas Gleixner
Browse files

genirq: Use IRQ_BITMAP_BITS as search size in irq_alloc_descs() 



The runtime expansion of nr_irqs does not take into account that
bitmap_find_next_zero_area() returns "start" + size in case the search
for an matching zero area fails. That results in a start value which
can be completely off and is not covered by the following
expand_nr_irqs() and possibly outside of the absolute limit. But we
use it without further checking.

Use IRQ_BITMAP_BITS as the limit for the bitmap search and expand
nr_irqs when the start bit is beyond nr_irqs. So start is always
pointing to the correct area in the bitmap. nr_irqs is just the limit
for irq enumerations, not the real limit for the irq space.

[ tglx: Let irq_expand_nr_irqs() take the new upper end so we do not
  	expand nr_irqs more than necessary. Made changelog readable ]

Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
LKML-Reference: <4D6014F9.8040605@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent a61d8258

kernel/irq/irqdesc.c

+8 −7
Original line number Diff line number Diff line
@@ -207,11 +207,11 @@ struct irq_desc * __ref irq_to_desc_alloc_node(unsigned int irq, int node) 
	return NULL;

}



static int irq_expand_nr_irqs(unsigned int cnt)

static int irq_expand_nr_irqs(unsigned int nr)

{

	if (nr_irqs + cnt > IRQ_BITMAP_BITS)

	if (nr > IRQ_BITMAP_BITS)

		return -ENOMEM;

	nr_irqs += cnt;

	nr_irqs = nr;

	return 0;

}
@@ -298,7 +298,7 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node) 
	return start;

}



static int irq_expand_nr_irqs(unsigned int cnt)

static int irq_expand_nr_irqs(unsigned int nr)

{

	return -ENOMEM;

}
@@ -346,13 +346,14 @@ irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node) 


	mutex_lock(&sparse_irq_lock);



	start = bitmap_find_next_zero_area(allocated_irqs, nr_irqs, from, cnt, 0);

	start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,

					   from, cnt, 0);

	ret = -EEXIST;

	if (irq >=0 && start != irq)

		goto err;



	if (start >= nr_irqs) {

		ret = irq_expand_nr_irqs(cnt);

	if (start + cnt > nr_irqs) {

		ret = irq_expand_nr_irqs(start + cnt);

		if (ret)

			goto err;

	}