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bpf, selftests: fix handling of sparse CPU allocations

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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>
This commit is contained in:
Martynas Pumputis 2019-01-31 10:19:33 +01:00 committed by Daniel Borkmann
parent 9d90436ece
commit 1bb54c4071
1 changed files with 21 additions and 11 deletions
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32
tools/testing/selftests/bpf/bpf_util.h
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@ -13,7 +13,7 @@ static inline unsigned int bpf_num_possible_cpus(void)
unsigned int start, end, possible_cpus = 0; unsigned int start, end, possible_cpus = 0;
char buff[128]; char buff[128];
FILE *fp; FILE *fp;
int n; int len, n, i, j = 0;
fp = fopen(fcpu, "r"); fp = fopen(fcpu, "r");
if (!fp) { if (!fp) {
@ -21,17 +21,27 @@ static inline unsigned int bpf_num_possible_cpus(void)
exit(1); exit(1);
} }
while (fgets(buff, sizeof(buff), fp)) { if (!fgets(buff, sizeof(buff), fp)) {
n = sscanf(buff, "%u-%u", &start, &end); printf("Failed to read %s!\n", fcpu);
if (n == 0) { exit(1);
printf("Failed to retrieve # possible CPUs!\n");
exit(1);
} else if (n == 1) {
end = start;
}
possible_cpus = start == 0 ? end + 1 : 0;
break;
} }
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;
}
}
fclose(fp); fclose(fp);
return possible_cpus; return possible_cpus;