[tip:perf/core] perf trace: Fix syscall enter formatting bug

[tip:perf/core] perf trace: Fix syscall enter formatting bug

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  6ebad5c101de0d43dafc9aff88bad45819f10470
Gitweb:     http://git.kernel.org/tip/6ebad5c101de0d43dafc9aff88bad45819f10470
Author:     Arnaldo Carvalho de Melo <acme@redhat.com>
AuthorDate: Wed, 25 Mar 2015 18:01:15 -0300
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 26 Mar 2015 10:52:29 -0300

perf trace: Fix syscall enter formatting bug

 commit e596663ebb28a068f5cca57f83285b7b293a2c83
 Author: Arnaldo Carvalho de Melo <acme@redhat.com>
 Date:   Fri Feb 13 13:22:21 2015 -0300

    perf trace: Handle multiple threads better wrt syscalls being intermixed

Introduced a bug where it considered the number of bytes output directly
to the output file when formatting the syscall entry buffer that is
stored to be finally printed at syscall exit, ending up leaving garbage
at the start of syscalls that appeared while another syscall was being
processed, in another thread. Fix it.

Example of garbage in the output before this patch:

 4280.102 (  0.000 ms): lsmd/763  ... [continued]: select()) = 0 Timeout
 4280.107 (275.250 ms): tuned/852 select(tvp: 0x7f41f7ffde50        ) ...
 4280.109 (  0.002 ms): lsmd/763 Xl��                                ) = -10
 4639.197 (  0.000 ms): systemd-journa/542  ... [continued]: epoll_wait()) = 1
 4639.202 (359.088 ms): lsmd/763 select(n: 6, inp: 0x7ffff21daad0, tvp: 0x7ffff21daac0) ...
 4639.207 (  0.005 ms): systemd-journa/542 Hn��                      ) = 106
 4639.221 (  0.002 ms): systemd-journa/542 uname(name: 0x7ffdbaed8e00) = 0
 4639.271 (  0.008 ms): systemd-journa/542 ftruncate(fd: 11</run/log/journal/60cd52417cf440a4a80107518bbd3c20/system.journal>, length: 50331648) = 0

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-9ckfe8mvsedgkg6y80gz1ul8@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 001c6ae..bcc98ce 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1735,7 +1735,7 @@ static int trace__sys_enter(struct trace *trace, struct perf_evsel *evsel,
 	}
 
 	if (!trace->summary_only)
-		printed += trace__printf_interrupted_entry(trace, sample);
+		trace__printf_interrupted_entry(trace, sample);
 
 	ttrace->entry_time = sample->time;
 	msg = ttrace->entry_str;