Commit 846de437 authored Apr 29, 2020 by Konstantin Khlebnikov Committed by Arnaldo Carvalho de Melo May 05, 2020

perf tools: Fix reading new topology attribute "core_cpus"



Check if access("devices/system/cpu/cpu%d/topology/core_cpus", F_OK)
fails, which will happen unless the current directory is "/sys".

Simply try to read this file first.

Fixes: 0ccdb840 ("perf tools: Apply new CPU topology sysfs attributes")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/158817718710.747528.11009278875028211991.stgit@buzz


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 4599d292

tools/perf/util/smt.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -24,13 +24,13 @@ int smt_on(void)

		snprintf(fn, sizeof fn,
		"devices/system/cpu/cpu%d/topology/core_cpus", cpu);
		if (access(fn, F_OK) == -1) {
		if (sysfs__read_str(fn, &str, &strlen) < 0) {
		snprintf(fn, sizeof fn,
		"devices/system/cpu/cpu%d/topology/thread_siblings",
		cpu);
		}
		if (sysfs__read_str(fn, &str, &strlen) < 0)
		continue;
		}
		/* Entry is hex, but does not have 0x, so need custom parser */
		siblings = strtoull(str, NULL, 16);
		free(str);

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