[tip:perf/core] perf header: Allow header->data_offset to be predetermined

[tip-bot for Adrian Hunter]

Commit-ID:  d645c442e68d24e64c46845bc8bb5d5a0a70b249
Gitweb:     http://git.kernel.org/tip/d645c442e68d24e64c46845bc8bb5d5a0a70b249
Author:     Adrian Hunter <adrian.hunter@xxxxxxxxx>
AuthorDate: Wed, 11 Dec 2013 14:36:28 +0200
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 13 Dec 2013 10:30:20 -0300

perf header: Allow header->data_offset to be predetermined

It will be necessary to predetermine header->data_offset to allow space
for attributes that are added later.  Consequently, do not change
header->data_offset if it is non-zero.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1386765443-26966-17-git-send-email-alexander.shishkin@xxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/header.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 0bb830f..61c5421 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2327,7 +2327,8 @@ int perf_session__write_header(struct perf_session *session,
 		}
 	}
 
-	header->data_offset = lseek(fd, 0, SEEK_CUR);
+	if (!header->data_offset)
+		header->data_offset = lseek(fd, 0, SEEK_CUR);
 	header->feat_offset = header->data_offset + header->data_size;
 
 	if (at_exit) {
--
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