* [PATCH v2 bpf] bpf: selftests: handle sparse CPU allocations
@ 2019-01-31 9:19 Martynas Pumputis
2019-01-31 16:48 ` Y Song
2019-01-31 22:26 ` Daniel Borkmann
0 siblings, 2 replies; 3+ messages in thread
From: Martynas Pumputis @ 2019-01-31 9:19 UTC (permalink / raw)
To: netdev; +Cc: ys114321, ast, daniel, m
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>
---
Testing of the patch: https://gist.github.com/brb/5369b5cfd08babb80cf2c4081dc19762
---
tools/testing/selftests/bpf/bpf_util.h | 31 +++++++++++++++++---------
1 file changed, 21 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h
index 315a44fa32af..442c3ab2d688 100644
--- a/tools/testing/selftests/bpf/bpf_util.h
+++ b/tools/testing/selftests/bpf/bpf_util.h
@@ -9,11 +9,12 @@
static inline unsigned int bpf_num_possible_cpus(void)
{
+
static const char *fcpu = "/sys/devices/system/cpu/possible";
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 +22,27 @@ 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) {
- 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;
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2 bpf] bpf: selftests: handle sparse CPU allocations
2019-01-31 9:19 [PATCH v2 bpf] bpf: selftests: handle sparse CPU allocations Martynas Pumputis
@ 2019-01-31 16:48 ` Y Song
2019-01-31 22:26 ` Daniel Borkmann
1 sibling, 0 replies; 3+ messages in thread
From: Y Song @ 2019-01-31 16:48 UTC (permalink / raw)
To: Martynas Pumputis; +Cc: netdev, Alexei Starovoitov, Daniel Borkmann
On Thu, Jan 31, 2019 at 1:18 AM Martynas Pumputis <m@lambda.lt> wrote:
>
> 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>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 bpf] bpf: selftests: handle sparse CPU allocations
2019-01-31 9:19 [PATCH v2 bpf] bpf: selftests: handle sparse CPU allocations Martynas Pumputis
2019-01-31 16:48 ` Y Song
@ 2019-01-31 22:26 ` Daniel Borkmann
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Borkmann @ 2019-01-31 22:26 UTC (permalink / raw)
To: Martynas Pumputis, netdev; +Cc: ys114321, ast
On 01/31/2019 10:19 AM, Martynas Pumputis wrote:
> 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>
>
> ---
> Testing of the patch: https://gist.github.com/brb/5369b5cfd08babb80cf2c4081dc19762
> ---
> tools/testing/selftests/bpf/bpf_util.h | 31 +++++++++++++++++---------
> 1 file changed, 21 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h
> index 315a44fa32af..442c3ab2d688 100644
> --- a/tools/testing/selftests/bpf/bpf_util.h
> +++ b/tools/testing/selftests/bpf/bpf_util.h
> @@ -9,11 +9,12 @@
>
> static inline unsigned int bpf_num_possible_cpus(void)
> {
> +
> static const char *fcpu = "/sys/devices/system/cpu/possible";
Applied and removed above whitespace while at it, thanks!
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-01-31 22:26 UTC | newest]
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2019-01-31 9:19 [PATCH v2 bpf] bpf: selftests: handle sparse CPU allocations Martynas Pumputis
2019-01-31 16:48 ` Y Song
2019-01-31 22:26 ` Daniel Borkmann
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