[PATCH 2/2] perf trace: Fix call-graph output

From: Ravi Bangoria
Date: Tue Jan 30 2018 - 00:29:37 EST


Recently, Arnaldo fixed global vs event specific --max-stack usage
with commit bd3dda9ab0fb ("perf trace: Allow overriding global
--max-stack per event"). This commit is having a regression when
we don't use --max-stack at all with perf trace. Ex,

$ ./perf trace record -g ls
$ ./perf trace -i perf.data
0.076 ( 0.002 ms): ls/9109 brk(
0.196 ( 0.008 ms): ls/9109 access(filename: 0x9f998b70, mode: R
0.209 ( 0.031 ms): ls/9109 open(filename: 0x9f998978, flags: CLOEXEC

This is missing call-traces.
After patch:

$ ./perf trace -i perf.data
0.076 ( 0.002 ms): ls/9109 brk(
do_syscall_trace_leave ([kernel.kallsyms])
[0] ([unknown])
syscall_exit_work ([kernel.kallsyms])
brk (/usr/lib64/ld-2.17.so)
_dl_sysdep_start (/usr/lib64/ld-2.17.so)
_dl_start_final (/usr/lib64/ld-2.17.so)
_dl_start (/usr/lib64/ld-2.17.so)
_start (/usr/lib64/ld-2.17.so)
0.196 ( 0.008 ms): ls/9109 access(filename: 0x9f998b70, mode: R
do_syscall_trace_leave ([kernel.kallsyms])
[0] ([unknown])

Fixes: bd3dda9ab0fb ("perf trace: Allow overriding global --max-stack per event")
Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxxxxxxx>
---
tools/perf/builtin-trace.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 17d11de..e90f5c3 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1661,9 +1661,12 @@ static int trace__resolve_callchain(struct trace *trace, struct perf_evsel *evse
struct callchain_cursor *cursor)
{
struct addr_location al;
+ int max_stack = evsel->attr.sample_max_stack ?
+ evsel->attr.sample_max_stack :
+ trace->max_stack;

if (machine__resolve(trace->host, &al, sample) < 0 ||
- thread__resolve_callchain(al.thread, cursor, evsel, sample, NULL, NULL, evsel->attr.sample_max_stack))
+ thread__resolve_callchain(al.thread, cursor, evsel, sample, NULL, NULL, max_stack))
return -1;

return 0;
--
1.8.3.1