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Subject[PATCH v2 1/3] perf tool: fix reading new topology attribute "core_cpus"
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Check access("devices/system/cpu/cpu%d/topology/core_cpus", F_OK) fails,
unless current directory is "/sys". Simply try read this file first.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 0ccdb8407a46 ("perf tools: Apply new CPU topology sysfs attributes")
---
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 3b791ef2cd50..8481842e9edb 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);
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