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SubjectRe: [PATCH]iova-lockdep-false-alarm-fix.

> Subject: [PATCH]iova-lockdep-false-alarm-fix.

Nice English titles, please...

On Wed, 20 Feb 2008 16:35:28 -0800 mark gross <mgross@linux.intel.com> wrote:

> lockdep goes off on the iova copy_reserved_iova because it and a
> function it calls grabs locks in the from, and the to of the copy
> operation.
>
> This patch gives the reserved_ioval_list locks special lockdep classes.
>
>

Confused. Why not fix the ranking inconsistency instead?

Your changelog doesn't tell us why this isn't a real bug?

> Index: linux-2.6.24-mm1/drivers/pci/intel-iommu.c
> ===================================================================
> --- linux-2.6.24-mm1.orig/drivers/pci/intel-iommu.c 2008-02-20 15:52:23.000000000 -0800
> +++ linux-2.6.24-mm1/drivers/pci/intel-iommu.c 2008-02-20 16:08:27.000000000 -0800
> @@ -1127,6 +1127,8 @@
> }
>
> static struct iova_domain reserved_iova_list;
> +static struct lock_class_key reserved_alloc_key;
> +static struct lock_class_key reserved_rbtree_key;
>
> static void dmar_init_reserved_ranges(void)
> {
> @@ -1137,6 +1139,11 @@
>
> init_iova_domain(&reserved_iova_list, DMA_32BIT_PFN);
>
> + lockdep_set_class(&reserved_iova_list.iova_alloc_lock,
> + &reserved_alloc_key);
> + lockdep_set_class(&reserved_iova_list.iova_rbtree_lock,
> + &reserved_rbtree_key);
> +
> /* IOAPIC ranges shouldn't be accessed by DMA */
> iova = reserve_iova(&reserved_iova_list, IOVA_PFN(IOAPIC_RANGE_START),
> IOVA_PFN(IOAPIC_RANGE_END));


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