From: Zhen Lei <[email protected]> Checking the IOVA bounds separately before deciding which direction to continue the search (if necessary) results in redundantly comparing both pfns twice each. GCC can already determine that the final comparison op is redundant and optimise it down to 3 in total, but we can go one further with a little tweak of the ordering (which makes the intent of the code that much cleaner as a bonus).
Signed-off-by: Zhen Lei <[email protected]> Tested-by: Ard Biesheuvel <[email protected]> Tested-by: Zhen Lei <[email protected]> [rm: rewrote commit message to clarify] Signed-off-by: Robin Murphy <[email protected]> --- v3: No change drivers/iommu/iova.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 246f14c83944..8f7552dc4e04 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -289,15 +289,12 @@ private_find_iova(struct iova_domain *iovad, unsigned long pfn) while (node) { struct iova *iova = rb_entry(node, struct iova, node); - /* If pfn falls within iova's range, return iova */ - if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) { - return iova; - } - if (pfn < iova->pfn_lo) node = node->rb_left; - else if (pfn > iova->pfn_lo) + else if (pfn > iova->pfn_hi) node = node->rb_right; + else + return iova; /* pfn falls within iova's range */ } return NULL; -- 2.13.4.dirty
