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

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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: 1d233886dd ("xdp: Use bulking for non-map XDP_REDIRECT and consolidate code paths")
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200218130334.29889-1-toke@redhat.com
This commit is contained in:
Toke Høiland-Jørgensen 2020-02-18 14:03:34 +01:00 committed by Daniel Borkmann
parent e20d3a055a
commit f25975f42f
2 changed files with 14 additions and 18 deletions
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16
include/uapi/linux/bpf.h
View File

@ -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

16
tools/include/uapi/linux/bpf.h
View File

@ -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