Previously, bpf_num_possible_cpus() had a bug when calculating a
number of possible CPUs in the case of sparse CPU allocations, as
it was considering only the first range or element of
/sys/devices/system/cpu/possible.
E.g. in the case of "0,2-3" (CPU 1 is not available), the function
returned 1 instead of 3.
This patch fixes the function by making it parse all CPU ranges and
elements.
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
unsigned int start, end, possible_cpus = 0;
char buff[128];
FILE *fp;
unsigned int start, end, possible_cpus = 0;
char buff[128];
FILE *fp;
fp = fopen(fcpu, "r");
if (!fp) {
fp = fopen(fcpu, "r");
if (!fp) {
- while (fgets(buff, sizeof(buff), fp)) {
- n = sscanf(buff, "%u-%u", &start, &end);
- if (n == 0) {
- printf("Failed to retrieve # possible CPUs!\n");
- exit(1);
- } else if (n == 1) {
- end = start;
+ if (!fgets(buff, sizeof(buff), fp)) {
+ printf("Failed to read %s!\n", fcpu);
+ exit(1);
+ }
+
+ len = strlen(buff);
+ for (i = 0; i <= len; i++) {
+ if (buff[i] == ',' || buff[i] == '\0') {
+ buff[i] = '\0';
+ n = sscanf(&buff[j], "%u-%u", &start, &end);
+ if (n <= 0) {
+ printf("Failed to retrieve # possible CPUs!\n");
+ exit(1);
+ } else if (n == 1) {
+ end = start;
+ }
+ possible_cpus += end - start + 1;
+ j = i + 1;
- possible_cpus = start == 0 ? end + 1 : 0;
- break;
fclose(fp);
return possible_cpus;
fclose(fp);
return possible_cpus;