linux-kernel - [PATCH 34/37] perf tools: Convert lseek + read to pread

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Date:	Wed, 24 Dec 2014 16:15:30 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 34/37] perf tools: Convert lseek + read to pread

When dso_cache__read() is called, it reads data from the given offset
using lseek + normal read syscall.  It can be combined to a single
pread syscall.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/dso.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index d8ee1fd826e7..95c8d5a2b934 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -593,10 +593,7 @@ dso_cache__read(struct dso *dso, struct machine *machine,
 		}
 	}
 
-	if (-1 == lseek(dso->data.fd, cache_offset, SEEK_SET))
-		goto err_unlock;
-
-	ret = read(dso->data.fd, cache->data, DSO__DATA_CACHE_SIZE);
+	ret = pread(dso->data.fd, cache->data, DSO__DATA_CACHE_SIZE, cache_offset);
 	if (ret <= 0)
 		goto err_unlock;
 
-- 
2.1.3

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