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Subject[tip:perf/core] perf symbols: Convert lseek + read to pread
Commit-ID:  c52686f9f888d23ca72f1309e86af8e91d075697
Gitweb: http://git.kernel.org/tip/c52686f9f888d23ca72f1309e86af8e91d075697
Author: Namhyung Kim <namhyung@kernel.org>
AuthorDate: Thu, 29 Jan 2015 17:02:01 -0300
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 29 Jan 2015 17:02:01 -0300

perf symbols: 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@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1422518843-25818-40-git-send-email-namhyung@kernel.org
[ Fixed it up when cherry picking it from the multi threaded patchkit ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/dso.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 45be944..c2f7d3b 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -532,12 +532,8 @@ dso_cache__read(struct dso *dso, u64 offset, u8 *data, ssize_t size)
break;

cache_offset = offset & DSO__DATA_CACHE_MASK;
- ret = -EINVAL;

- if (-1 == lseek(dso->data.fd, cache_offset, SEEK_SET))
- break;
-
- 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)
break;


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