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Sender: Jan Blunck <jblunck@gmail.com>
From: Jan Blunck <jblunck@infradead.org>
To: dev@dpdk.org
Cc: shreyansh.jain@nxp.com, david.marchand@6wind.com,
Jan Viktorin <viktorin@rehivetech.com>
Date: Mon, 21 Nov 2016 17:55:15 +0100
Message-Id: <1479747322-5774-1-git-send-email-jblunck@infradead.org>
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Subject: [dpdk-dev] [PATCH v2 1/8] eal: define container_of macro
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This macro is based on Jan Viktorin's original patch but also checks the
type of the passed pointer against the type of the member.
Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
[jblunck@infradead.org: add type checking and __extension__]
Signed-off-by: Jan Blunck <jblunck@infradead.org>
---
lib/librte_eal/common/include/rte_common.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
index db5ac91..8dda3e2 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -331,6 +331,26 @@ rte_bsf32(uint32_t v)
#define offsetof(TYPE, MEMBER) __builtin_offsetof (TYPE, MEMBER)
#endif
+/**
+ * Return pointer to the wrapping struct instance.
+ *
+ * Example:
+ *
+ * struct wrapper {
+ * ...
+ * struct child c;
+ * ...
+ * };
+ *
+ * struct child *x = obtain(...);
+ * struct wrapper *w = container_of(x, struct wrapper, c);
+ */
+#ifndef container_of
+#define container_of(ptr, type, member) __extension__ ({ \
+ typeof(((type *)0)->member) *_ptr = (ptr); \
+ (type *)(((char *)_ptr) - offsetof(type, member)); })
+#endif
+
#define _RTE_STR(x) #x
/** Take a macro value and get a string version of it */
#define RTE_STR(x) _RTE_STR(x)
--
2.7.4