Commit f25975f4 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Daniel Borkmann
Browse files

bpf, uapi: Remove text about bpf_redirect_map() giving higher performance 



The performance of bpf_redirect() is now roughly the same as that of
bpf_redirect_map(). However, David Ahern pointed out that the header file
has not been updated to reflect this, and still says that a significant
performance increase is possible when using bpf_redirect_map(). Remove this
text from the bpf_redirect_map() description, and reword the description in
bpf_redirect() slightly. Also fix the 'Return' section of the
bpf_redirect_map() documentation.

Fixes: 1d233886 ("xdp: Use bulking for non-map XDP_REDIRECT and consolidate code paths")
Reported-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200218130334.29889-1-toke@redhat.com
parent e20d3a05

include/uapi/linux/bpf.h

+7 −9
Original line number Diff line number Diff line
@@ -1045,9 +1045,9 @@ union bpf_attr { 
 * 		supports redirection to the egress interface, and accepts no

 * 		flag at all.

 *

 * 		The same effect can be attained with the more generic

 * 		**bpf_redirect_map**\ (), which requires specific maps to be

 * 		used but offers better performance.

 * 		The same effect can also be attained with the more generic

 * 		**bpf_redirect_map**\ (), which uses a BPF map to store the

 * 		redirect target instead of providing it directly to the helper.

 * 	Return

 * 		For XDP, the helper returns **XDP_REDIRECT** on success or

 * 		**XDP_ABORTED** on error. For other program types, the values
@@ -1611,13 +1611,11 @@ union bpf_attr { 
 * 		the caller. Any higher bits in the *flags* argument must be

 * 		unset.

 *

 * 		When used to redirect packets to net devices, this helper

 * 		provides a high performance increase over **bpf_redirect**\ ().

 * 		This is due to various implementation details of the underlying

 * 		mechanisms, one of which is the fact that **bpf_redirect_map**\

 * 		() tries to send packet as a "bulk" to the device.

 * 		See also bpf_redirect(), which only supports redirecting to an

 * 		ifindex, but doesn't require a map to do so.

 * 	Return

 * 		**XDP_REDIRECT** on success, or **XDP_ABORTED** on error.

 * 		**XDP_REDIRECT** on success, or the value of the two lower bits

 * 		of the **flags* argument on error.

 *

 * int bpf_sk_redirect_map(struct sk_buff *skb, struct bpf_map *map, u32 key, u64 flags)

 * 	Description

tools/include/uapi/linux/bpf.h

+7 −9
Original line number Diff line number Diff line
@@ -1045,9 +1045,9 @@ union bpf_attr { 
 * 		supports redirection to the egress interface, and accepts no

 * 		flag at all.

 *

 * 		The same effect can be attained with the more generic

 * 		**bpf_redirect_map**\ (), which requires specific maps to be

 * 		used but offers better performance.

 * 		The same effect can also be attained with the more generic

 * 		**bpf_redirect_map**\ (), which uses a BPF map to store the

 * 		redirect target instead of providing it directly to the helper.

 * 	Return

 * 		For XDP, the helper returns **XDP_REDIRECT** on success or

 * 		**XDP_ABORTED** on error. For other program types, the values
@@ -1611,13 +1611,11 @@ union bpf_attr { 
 * 		the caller. Any higher bits in the *flags* argument must be

 * 		unset.

 *

 * 		When used to redirect packets to net devices, this helper

 * 		provides a high performance increase over **bpf_redirect**\ ().

 * 		This is due to various implementation details of the underlying

 * 		mechanisms, one of which is the fact that **bpf_redirect_map**\

 * 		() tries to send packet as a "bulk" to the device.

 * 		See also bpf_redirect(), which only supports redirecting to an

 * 		ifindex, but doesn't require a map to do so.

 * 	Return

 * 		**XDP_REDIRECT** on success, or **XDP_ABORTED** on error.

 * 		**XDP_REDIRECT** on success, or the value of the two lower bits

 * 		of the **flags* argument on error.

 *

 * int bpf_sk_redirect_map(struct sk_buff *skb, struct bpf_map *map, u32 key, u64 flags)

 * 	Description

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