Commit 94984bfe authored by Eric Dumazet's avatar Eric Dumazet Committed by Andrew Morton
Browse files

rbtree: inline rb_last() 

This is a very small function, inlining it saves cpu cycles in TCP by
reducing register pressure and removing call/ret overhead.

It also reduces vmlinux text size by 122 bytes on a typical x86_64 build.

Before:

size vmlinux
   text    data     bss     dec     hex filename
34811781        22177365        5685248 62674394        3bc55da vmlinux

After:

size vmlinux
   text	   data	    bss	    dec	    hex	filename
34811659	22177365	5685248	62674272	3bc5560	vmlinux

[ojeda@kernel.org: fix rust build]
  Link: https://lkml.kernel.org/r/20251120085518.1463498-1-ojeda@kernel.org
Link: https://lkml.kernel.org/r/20251114140646.3817319-3-edumazet@google.com


Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
Reviewed-by: default avatarKuan-Wei Chiu <visitorckw@gmail.com>
Cc: Jakub Kacinski <kuba@kernel.org>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Stehen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c2d2dad2

include/linux/rbtree.h

+15 −1
Original line number Diff line number Diff line
@@ -58,7 +58,21 @@ static inline struct rb_node *rb_first(const struct rb_root *root) 
		n = n->rb_left;

	return n;

}

extern struct rb_node *rb_last(const struct rb_root *);



/*

 * This function returns the last node (in sort order) of the tree.

 */

static inline struct rb_node *rb_last(const struct rb_root *root)

{

	struct rb_node	*n;



	n = root->rb_node;

	if (!n)

		return NULL;

	while (n->rb_right)

		n = n->rb_right;

	return n;

}



/* Postorder iteration - always visit the parent after its children */

extern struct rb_node *rb_first_postorder(const struct rb_root *);

lib/rbtree.c

+0 −13
Original line number Diff line number Diff line
@@ -460,19 +460,6 @@ void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, 
}

EXPORT_SYMBOL(__rb_insert_augmented);



struct rb_node *rb_last(const struct rb_root *root)

{

	struct rb_node	*n;



	n = root->rb_node;

	if (!n)

		return NULL;

	while (n->rb_right)

		n = n->rb_right;

	return n;

}

EXPORT_SYMBOL(rb_last);



struct rb_node *rb_next(const struct rb_node *node)

{

	struct rb_node *parent;

rust/helpers/rbtree.c

+5 −0
Original line number Diff line number Diff line
@@ -12,3 +12,8 @@ struct rb_node *rust_helper_rb_first(const struct rb_root *root) 
{

	return rb_first(root);

}



struct rb_node *rust_helper_rb_last(const struct rb_root *root)

{

	return rb_last(root);

}