From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
Date: Tue, 18 Feb 2020 14:03:34 +0100
Subject: bpf, uapi: Remove text about bpf_redirect_map() giving higher
performance
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Patch-mainline: v5.6-rc3
Git-commit: f25975f42f2f8f2a01303054d6a70c7ceb1fcf54
References: bsc#1177028
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: 1d233886dd90 ("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
Acked-by: Gary Lin <glin@suse.com>
---
include/uapi/linux/bpf.h | 16 +++++++---------
tools/include/uapi/linux/bpf.h | 16 +++++++---------
2 files changed, 14 insertions(+), 18 deletions(-)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1040,9 +1040,9 @@ 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
@@ -1606,13 +1606,11 @@ 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
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1018,9 +1018,9 @@ 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
@@ -1584,13 +1584,11 @@ 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