[tip:perfcounters/urgent] perf util: Fix do_read() to fail on EOF instead of busy-looping

[tip-bot for Pierre Habouzit <pierre.habouzit@intersec.com>]

Commit-ID:  47efff9a9b958f1c459a4c669168be0de474a9e3
Gitweb:     http://git.kernel.org/tip/47efff9a9b958f1c459a4c669168be0de474a9e3
Author:     Pierre Habouzit <pierre.habouzit@intersec.com>
AuthorDate: Fri, 7 Aug 2009 14:16:00 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 7 Aug 2009 17:08:17 +0200

perf util: Fix do_read() to fail on EOF instead of busy-looping

While toying with perf, I've noticed that perf record can
easily enter a busy loop when doing something as silly as:

    $ perf record -A ls

Yeah, do_read here really wants to read a known size, not being
able to should die(), not busy-loop ;)

That was the cause for the bug.

Signed-off-by: Pierre Habouzit <pierre.habouzit@intersec.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1249647361-11582-2-git-send-email-pierre.habouzit@intersec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 tools/perf/util/header.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 95a44bc..b92a457 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -185,6 +185,8 @@ static void do_read(int fd, void *buf, size_t size)
 
 		if (ret < 0)
 			die("failed to read");
+		if (ret == 0)
+			die("failed to read: missing data");
 
 		size -= ret;
 		buf += ret;