From 846de4371fdfddfa49481e3d04884539870dc127 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Wed, 29 Apr 2020 19:19:47 +0300 Subject: [PATCH] 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: 0ccdb8407a46 ("perf tools: Apply new CPU topology sysfs attributes") Signed-off-by: Konstantin Khlebnikov Cc: Andi Kleen Cc: Dmitry Monakhov Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/158817718710.747528.11009278875028211991.stgit@buzz Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/smt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c index 3b791ef..8481842 100644 --- a/tools/perf/util/smt.c +++ b/tools/perf/util/smt.c @@ -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; } - 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); -- 2.7.4