perf tools: Handle TOPOLOGY headers with no CPU

[ Upstream commit 1497e804d1a6e2bd9107ddf64b0310449f4673eb ]

This patch fixes an issue in cpumap.c when used with the TOPOLOGY
header. In some configurations, some NUMA nodes may have no CPU (empty
cpulist). Yet a cpumap map must be created otherwise perf abort with an
error. This patch handles this case by creating a dummy map.

  Before:

  $ perf record -o - -e cycles noploop 2 | perf script -i -
  0x6e8 [0x6c]: failed to process type: 80

  After:

  $ perf record -o - -e cycles noploop 2 | perf script -i -
  noploop for 2 seconds

Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1547885559-1657-1-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 2c0b522..a625cb1 100644 (file)
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -129,7 +129,12 @@ struct cpu_map *cpu_map__new(const char *cpu_list)
        if (!cpu_list)
                return cpu_map__read_all_cpu_map();
 
-       if (!isdigit(*cpu_list))
+       /*
+        * must handle the case of empty cpumap to cover
+        * TOPOLOGY header for NUMA nodes with no CPU
+        * ( e.g., because of CPU hotplug)
+        */
+       if (!isdigit(*cpu_list) && *cpu_list != '\0')
                goto out;
 
        while (isdigit(*cpu_list)) {
@@ -176,8 +181,10 @@ struct cpu_map *cpu_map__new(const char *cpu_list)
 
        if (nr_cpus > 0)
                cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
-       else
+       else if (*cpu_list != '\0')
                cpus = cpu_map__default_new();
+       else
+               cpus = cpu_map__dummy_new();
 invalid:
        free(tmp_cpus);
 out: