diff options
| author | Zhen Lei <[email protected]> | 2017-09-21 16:52:42 +0100 |
|---|---|---|
| committer | Joerg Roedel <[email protected]> | 2017-09-27 17:09:56 +0200 |
| commit | 2070f940a6d5148cf2df0d0087ff0a64d9f15237 (patch) | |
| tree | 33eaa069e7e259009034651a3241ee8318ee55b9 | |
| parent | e19b205be43d11bff638cad4487008c48d21c103 (diff) | |
iommu/iova: Optimise rbtree searching
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]>
Tested-by: Nate Watterson <[email protected]>
[rm: rewrote commit message to clarify]
Signed-off-by: Robin Murphy <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>
| -rw-r--r-- | drivers/iommu/iova.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 33edfa794ae9..f129ff4f5c89 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -342,15 +342,12 @@ 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; |