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[bpf-next,v4,17/21] tools/libpf: add offsetof/container_of macro in bpf_helpers.h

Message ID 20200509175919.2477104-1-yhs@fb.com
State Superseded
Headers show
Series bpf: implement bpf iterator for kernel data | expand

Commit Message

Yonghong Song May 9, 2020, 5:59 p.m. UTC 
These two helpers will be used later in bpf_iter bpf program
bpf_iter_netlink.c. Put them in bpf_helpers.h since they could
be useful in other cases.

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/lib/bpf/bpf_helpers.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
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Patch

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index da00b87aa199..f67dce2af802 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -36,6 +36,20 @@ 
 #define __weak __attribute__((weak))
 #endif
 
+/*
+ * Helper macro to manipulate data structures
+ */
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER)  ((size_t)&((TYPE *)0)->MEMBER)
+#endif
+#ifndef container_of
+#define container_of(ptr, type, member)				\
+	({							\
+		void *__mptr = (void *)(ptr);			\
+		((type *)(__mptr - offsetof(type, member)));	\
+	})
+#endif
+
 /*
  * Helper structure used by eBPF C program
  * to describe BPF map attributes to libbpf loader