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-rw-r--r--tools/lib/bpf/libbpf.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6718d0b90130..2e84fa5b8479 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4995,13 +4995,15 @@ int libbpf_num_possible_cpus(void)
static const char *fcpu = "/sys/devices/system/cpu/possible";
int len = 0, n = 0, il = 0, ir = 0;
unsigned int start = 0, end = 0;
+ int tmp_cpus = 0;
static int cpus;
char buf[128];
int error = 0;
int fd = -1;
- if (cpus > 0)
- return cpus;
+ tmp_cpus = READ_ONCE(cpus);
+ if (tmp_cpus > 0)
+ return tmp_cpus;
fd = open(fcpu, O_RDONLY);
if (fd < 0) {
@@ -5024,7 +5026,7 @@ int libbpf_num_possible_cpus(void)
}
buf[len] = '\0';
- for (ir = 0, cpus = 0; ir <= len; ir++) {
+ for (ir = 0, tmp_cpus = 0; ir <= len; ir++) {
/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
if (buf[ir] == ',' || buf[ir] == '\0') {
buf[ir] = '\0';
@@ -5036,13 +5038,15 @@ int libbpf_num_possible_cpus(void)
} else if (n == 1) {
end = start;
}
- cpus += end - start + 1;
+ tmp_cpus += end - start + 1;
il = ir + 1;
}
}
- if (cpus <= 0) {
- pr_warning("Invalid #CPUs %d from %s\n", cpus, fcpu);
+ if (tmp_cpus <= 0) {
+ pr_warning("Invalid #CPUs %d from %s\n", tmp_cpus, fcpu);
return -EINVAL;
}
- return cpus;
+
+ WRITE_ONCE(cpus, tmp_cpus);
+ return tmp_cpus;
}