Commit c2d2dad2 authored by Eric Dumazet's avatar Eric Dumazet Committed by Andrew Morton
Browse files

rbtree: inline rb_first() 

Patch series "rbree: inline rb_first() and rb_last()".

Inline these two small helpers, heavily used in TCP and FQ packet scheduler,
and in many other places.

This reduces kernel text size, and brings an 1.5 % improvement on network
TCP stress test.


This patch (of 2):

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

It also reduces vmlinux text size by 744 bytes on a typical x86_64 build.

Before:

size vmlinux
   text	   data	    bss	    dec	    hex	filename
34812525	22177365	5685248	62675138	3bc58c2	vmlinux

After:

size vmlinux
   text	   data	    bss	    dec	    hex	filename
34811781	22177365	5685248	62674394	3bc55da	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/20251114140646.3817319-1-edumazet@google.com
Link: https://lkml.kernel.org/r/20251114140646.3817319-2-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 bc947af6

include/linux/rbtree.h

+15 −1
Original line number Diff line number Diff line
@@ -43,7 +43,21 @@ extern void rb_erase(struct rb_node *, struct rb_root *); 
/* Find logical next and previous nodes in a tree */

extern struct rb_node *rb_next(const struct rb_node *);

extern struct rb_node *rb_prev(const struct rb_node *);

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



/*

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

 */

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

{

	struct rb_node	*n;



	n = root->rb_node;

	if (!n)

		return NULL;

	while (n->rb_left)

		n = n->rb_left;

	return n;

}

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



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

lib/rbtree.c

+0 −16
Original line number Diff line number Diff line
@@ -460,22 +460,6 @@ void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, 
}

EXPORT_SYMBOL(__rb_insert_augmented);



/*

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

 */

struct rb_node *rb_first(const struct rb_root *root)

{

	struct rb_node	*n;



	n = root->rb_node;

	if (!n)

		return NULL;

	while (n->rb_left)

		n = n->rb_left;

	return n;

}

EXPORT_SYMBOL(rb_first);



struct rb_node *rb_last(const struct rb_root *root)

{

	struct rb_node	*n;

rust/helpers/rbtree.c

+5 −0
Original line number Diff line number Diff line
@@ -7,3 +7,8 @@ void rust_helper_rb_link_node(struct rb_node *node, struct rb_node *parent, 
{

	rb_link_node(node, parent, rb_link);

}



struct rb_node *rust_helper_rb_first(const struct rb_root *root)

{

	return rb_first(root);

}