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lib/interval_tree: skip the check before go to the right subtree

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The interval_tree_subtree_search() holds the loop invariant:

    start <= node->ITSUBTREE

Let's say we have a following tree:

         node
         /  \
      left  right

So we know node->ITSUBTREE is contributed by one of the following:

  * left->ITSUBTREE
  * ITLAST(node)
  * right->ITSUBTREE

When we come to the right node, we are sure the first two don't
contribute to node->ITSUBTREE and it must be the right node does the
job.

So skip the check before go to the right subtree.

Link: https://lkml.kernel.org/r/20250310074938.26756-7-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michel Lespinasse <michel@lespinasse.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Wei Yang 2025-03-10 07:49:37 +00:00 • committed by Andrew Morton
parent ccaf3efcee
commit 1981128578
1 changed files with 2 additions and 6 deletions
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8
include/linux/interval_tree_generic.h
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@ -104,12 +104,8 @@ ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
if (ITSTART(node) <= last) { /* Cond1 */ \
if (start <= ITLAST(node)) /* Cond2 */ \
return node; /* node is leftmost match */ \
if (node->ITRB.rb_right) { \
node = rb_entry(node->ITRB.rb_right, \
ITSTRUCT, ITRB); \
if (start <= node->ITSUBTREE) \
continue; \
} \
node = rb_entry(node->ITRB.rb_right, ITSTRUCT, ITRB); \
continue; \
} \
return NULL; /* No match */ \
} \