From 8d9cbd8f870e1aab00fb0f8a465887877a1d6f82 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 13 Jan 2015 19:13:23 +0530 Subject: [PATCH] perf evsel: Don't rely on malloc working for sz 0 When running perf on ARC (uClibc based userspace), ran into this issue ------------->8---------------- [ARCLinux]$ ./perf record ls bin etc perf sys debug init perf.data tmp [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (~24 samples) ] [ARCLinux]$ ./perf report incompatible file format (rerun with -v to learn more) ------------->8---------------- The problem happens in the following call stack when zalloc is called with size zero glibc default / uClibc with MALLOC_GLIBC_COMPAT are OK, but not if that config option is not enabled. cmd_report perf_session__new perf_session__open perf_session__read_header read_attr(fd, header, &f_attr) nr_ids = f_attr.ids.size / sizeof(u64); <-- 0 perf_evsel__alloc_id(vsel, 1, nr_ids) zalloc(ncpus * nthreads * sizeof(u64)) <-- 0 header.c: read_attr() (gdb) p *f_attr $17 = { attr = { type = 0, size = 96, config = 0, { sample_period = 4000, sample_freq = 4000 }, ... ids = { offset = 104, size = 0 <------ } } Signed-off-by: Vineet Gupta Suggested-by: Namhyung Kim Acked-by: Jiri Olsa Cc: Alexey Brodkin Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1421156604-30603-5-git-send-email-vgupta@synopsys.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evsel.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 1e90c8557ede..1d826d63bc20 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -797,6 +797,9 @@ int perf_evsel__enable(struct perf_evsel *evsel, int ncpus, int nthreads) int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads) { + if (ncpus == 0 || nthreads == 0) + return 0; + if (evsel->system_wide) nthreads = 1; -- 2.20.1