netdev - [PATCH bpf-next v2 2/3] bpf: add msg_pop

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Message-Id: <1543270579-1405-3-git-send-email-john.fastabend@gmail.com>
Date:   Mon, 26 Nov 2018 14:16:18 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     ast@...nel.org, daniel@...earbox.net
Cc:     john.fastabend@...il.com, netdev@...r.kernel.org
Subject: [PATCH bpf-next v2 2/3] bpf: add msg_pop_data helper to tools

Add the necessary header definitions to tools for new
msg_pop_data_helper.

Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
 tools/include/uapi/linux/bpf.h            | 16 +++++++++++++++-
 tools/testing/selftests/bpf/bpf_helpers.h |  2 ++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 23e2031..597afdb 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -2268,6 +2268,19 @@ union bpf_attr {
  *
  *	Return
  *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_msg_pop_data(struct sk_msg_buff *msg, u32 start, u32 pop, u64 flags)
+ *	 Description
+ *		Will remove *pop* bytes from a *msg* starting at byte *start*.
+ *		This may result in **ENOMEM** errors under certain situations if
+ *		an allocation and copy are required due to a full ring buffer.
+ *		However, the helper will try to avoid doing the allocation
+ *		if possible. Other errors can occur if input parameters are
+ *		invalid either due to *start* byte not being valid part of msg
+ *		payload and/or *pop* value being to large.
+ *
+ *	Return
+ *		0 on success, or a negative erro in case of failure.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2360,7 +2373,8 @@ union bpf_attr {
 	FN(map_push_elem),		\
 	FN(map_pop_elem),		\
 	FN(map_peek_elem),		\
-	FN(msg_push_data),
+	FN(msg_push_data),		\
+	FN(msg_pop_data),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 686e57c..7b69519 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -113,6 +113,8 @@ static int (*bpf_msg_pull_data)(void *ctx, int start, int end, int flags) =
 	(void *) BPF_FUNC_msg_pull_data;
 static int (*bpf_msg_push_data)(void *ctx, int start, int end, int flags) =
 	(void *) BPF_FUNC_msg_push_data;
+static int (*bpf_msg_pop_data)(void *ctx, int start, int cut, int flags) =
+	(void *) BPF_FUNC_msg_pop_data;
 static int (*bpf_bind)(void *ctx, void *addr, int addr_len) =
 	(void *) BPF_FUNC_bind;
 static int (*bpf_xdp_adjust_tail)(void *ctx, int offset) =
-- 
2.7.4