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From: Shreyansh Jain <shreyansh.jain@nxp.com>
Subject: [PATCH v10 01/25] eal: define container macro
Date: Fri, 16 Sep 2016 09:59:36 +0530
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 <1474000200-16705-1-git-send-email-shreyansh.jain@nxp.com>
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Cc: <viktorin@rehivetech.com>, David Marchand <david.marchand@6wind.com>,
 <hemant.agrawal@nxp.com>, Thomas Monjalon <thomas.monjalon@6wind.com>,
 Shreyansh Jain <shreyansh.jain@nxp.com>
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From: Jan Viktorin <viktorin@rehivetech.com>

Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
---
 lib/librte_eal/common/include/rte_common.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
index db5ac91..7f9e4dd 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -331,6 +331,27 @@ 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);
+ *
+ * Some implementation already have this defined, thus, conditional
+ * declaration.
+ */
+#ifndef container_of
+#define container_of(p, type, member) \
+	((type *) (((char *) (p)) - 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