On 02/19/2011 04:15 AM, tip-bot for Thomas Gleixner wrote:
> Commit-ID: e7bcecb7b1d29b9ad5af939149a945658620ca8f
> Gitweb: http://git.kernel.org/tip/e7bcecb7b1d29b9ad5af939149a945658620ca8f
> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> AuthorDate: Wed, 16 Feb 2011 17:12:57 +0100
> Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> CommitDate: Sat, 19 Feb 2011 12:58:06 +0100
>
> genirq: Make nr_irqs runtime expandable
>
> We face more and more the requirement to expand nr_irqs at
> runtime. The reason are irq expanders which can not be detected in the
> early boot stage. So we speculate nr_irqs to have enough room. Further
> Xen needs extra irq numbers and we really want to avoid adding more
> "detection" code into the early boot. There is no real good reason why
> we need to limit nr_irqs at early boot.
>
> Allow the allocation code to expand nr_irqs. We have already 8k extra
> number space in the allocation bitmap, so lets use it.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
> kernel/irq/irqdesc.c | 22 +++++++++++++++++++---
> 1 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index a250d3a..6f6644f 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -206,6 +206,14 @@ 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)
> +{
> + if (nr_irqs + cnt > IRQ_BITMAP_BITS)
> + return -ENOMEM;
> + nr_irqs += cnt;
> + return 0;
> +}
> +
> int __init early_irq_init(void)
> {
> int i, initcnt, node = first_online_node;
> @@ -287,6 +295,12 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node)
> {
> return start;
> }
> +
> +static int irq_expand_nr_irqs(unsigned int cnt)
> +{
> + return -ENOMEM;
> +}
> +
> #endif /* !CONFIG_SPARSE_IRQ */
>
> /* Dynamic interrupt handling */
> @@ -335,9 +349,11 @@ irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node)
> if (irq >=0 && start != irq)
> goto err;
>
> - ret = -ENOMEM;
> - if (start >= nr_irqs)
> - goto err;
> + if (start >= nr_irqs) {
> + ret = irq_expand_nr_irqs(cnt);
> + if (ret)
> + goto err;
> + }
may need following patch.
[PATCH] genirq: use IRQ_BITMAP_BITS as search size
instead of nr_irqs.
Otherwise bitmap_find_next_area could exit with larger start and in extreme
case we could fail to get wrong irqs return.
For example:
IRQ_BITMAP_BITS=10240
nr_irqs=8192
cnt=2048
and bit 0 to bit 8190 are set already.
before patch start from bit_find_next_area() will be 8191+2048.
later irq_expand_nr_irqs will set nr_irqs 10240.
finally irq_alloc_descs will return [8191+2048, 8191+2048+2047] happily..
with this patch, will get correct [8191, 8191+2047]
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
kernel/irq/irqdesc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
Index: linux-2.6/kernel/irq/irqdesc.c
===================================================================
--- linux-2.6.orig/kernel/irq/irqdesc.c
+++ linux-2.6/kernel/irq/irqdesc.c
@@ -346,12 +346,13 @@ irq_alloc_descs(int irq, unsigned int fr
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) {
+ if (start + cnt > nr_irqs) {
ret = irq_expand_nr_irqs(cnt);
if (ret)
goto err;
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|