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

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Message-Id: <1542937130-4860-3-git-send-email-john.fastabend@gmail.com>
Date:   Thu, 22 Nov 2018 17:38:49 -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 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            | 13 ++++++++++++-
 tools/testing/selftests/bpf/bpf_helpers.h |  2 ++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c1554aa..95cf7a5 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -2268,6 +2268,16 @@ 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 result in ENOMEM errors under certain situations where
+ * 		a 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 do to start byte not being valid part of msg
+ * 		payload and/or pop value being to large.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2360,7 +2370,8 @@ 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