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From:   Zong Li <zong@andestech.com>
To:     <rostedt@goodmis.org>, <mingo@redhat.com>, <dsahern@gmail.com>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     <zongbox@gmail.com>, <greentime@andestech.com>,
        Zong Li <zong@andestech.com>
Subject: [PATCH] net: Change the layout of structure trace_event_raw_fib_table_lookup
Date:   Mon, 13 Aug 2018 10:26:52 +0800
Message-ID: <1534127212-13186-1-git-send-email-zong@andestech.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

There is an unalignment access about the structure
'trace_event_raw_fib_table_lookup'.

In include/trace/events/fib.h, there is a memory operation which casting
the 'src' data member to a pointer, and then store a value to this
pointer point to.

p32 = (__be32 *) __entry->src;
*p32 = flp->saddr;

The offset of 'src' in structure trace_event_raw_fib_table_lookup is not
four bytes alignment. On some architectures, they don't permit the
unalignment access, it need to pay the price to handle this situation in
exception handler.

Adjust the layout of structure to avoid this case.

Signed-off-by: Zong Li <zong@andestech.com>
---
 include/trace/events/fib.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/trace/events/fib.h b/include/trace/events/fib.h
index 9763cddd0594..6271bab63bfb 100644
--- a/include/trace/events/fib.h
+++ b/include/trace/events/fib.h
@@ -22,6 +22,7 @@ TRACE_EVENT(fib_table_lookup,
 		__field(	int,	err		)
 		__field(	int,	oif		)
 		__field(	int,	iif		)
+		__field(	u8,	proto		)
 		__field(	__u8,	tos		)
 		__field(	__u8,	scope		)
 		__field(	__u8,	flags		)
@@ -31,7 +32,6 @@ TRACE_EVENT(fib_table_lookup,
 		__array(	__u8,	saddr,	4	)
 		__field(	u16,	sport		)
 		__field(	u16,	dport		)
-		__field(	u8,	proto		)
 		__dynamic_array(char,  name,   IFNAMSIZ )
 	),
 
-- 
2.16.1