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Commit 1bb54c40 authored by Martynas Pumputis's avatar Martynas Pumputis Committed by Daniel Borkmann
Browse files

bpf, selftests: fix handling of sparse CPU allocations 



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: default avatarMartynas Pumputis <m@lambda.lt>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 9d90436e

tools/testing/selftests/bpf/bpf_util.h

+20 −10
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ static inline unsigned int bpf_num_possible_cpus(void) 
	unsigned int start, end, possible_cpus = 0;

	char buff[128];

	FILE *fp;

	int n;

	int len, n, i, j = 0;



	fp = fopen(fcpu, "r");

	if (!fp) {
@@ -21,17 +21,27 @@ static inline unsigned int bpf_num_possible_cpus(void) 
		exit(1);

	}



	while (fgets(buff, sizeof(buff), fp)) {

		n = sscanf(buff, "%u-%u", &start, &end);

		if (n == 0) {

	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 = start == 0 ? end + 1 : 0;

		break;

			possible_cpus += end - start + 1;

			j = i + 1;

		}

	}



	fclose(fp);



	return possible_cpus;