On Thu, Jun 06, 2019 at 09:58:37AM -0700, Hechao Li wrote:
> Use the newly added bpf_num_possible_cpus() in bpftool and selftests
> and remove duplicate implementations.
>
> Signed-off-by: Hechao Li <hech...@fb.com>
> ---
> tools/bpf/bpftool/common.c | 53 +++-----------------------
> tools/testing/selftests/bpf/bpf_util.h | 37 +++---------------
> 2 files changed, 10 insertions(+), 80 deletions(-)
>
> diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
> index f7261fad45c1..0b1c56758cd9 100644
> --- a/tools/bpf/bpftool/common.c
> +++ b/tools/bpf/bpftool/common.c
> @@ -21,6 +21,7 @@
> #include <sys/vfs.h>
>
> #include <bpf.h>
> +#include <libbpf.h> /* libbpf_num_possible_cpus */
>
> #include "main.h"
>
> @@ -439,57 +440,13 @@ unsigned int get_page_size(void)
>
> unsigned int get_possible_cpus(void)
> {
> - static unsigned int result;
> - char buf[128];
> - long int n;
> - char *ptr;
> - int fd;
> -
> - if (result)
> - return result;
> -
> - fd = open("/sys/devices/system/cpu/possible", O_RDONLY);
> - if (fd < 0) {
> - p_err("can't open sysfs possible cpus");
> - exit(-1);
> - }
> -
> - n = read(fd, buf, sizeof(buf));
> - if (n < 2) {
> - p_err("can't read sysfs possible cpus");
> - exit(-1);
> - }
> - close(fd);
> + int cpus = libbpf_num_possible_cpus();
>
> - if (n == sizeof(buf)) {
> - p_err("read sysfs possible cpus overflow");
> + if (cpus <= 0) {
> + p_err("can't get # of possible cpus");
> exit(-1);
> }
> -
> - ptr = buf;
> - n = 0;
> - while (*ptr && *ptr != '\n') {
> - unsigned int a, b;
> -
> - if (sscanf(ptr, "%u-%u", &a, &b) == 2) {
> - n += b - a + 1;
> -
> - ptr = strchr(ptr, '-') + 1;
> - } else if (sscanf(ptr, "%u", &a) == 1) {
> - n++;
> - } else {
> - assert(0);
> - }
> -
> - while (isdigit(*ptr))
> - ptr++;
> - if (*ptr == ',')
> - ptr++;
> - }
> -
> - result = n;
> -
> - return result;
> + return cpus;
> }
>
> static char *
> diff --git a/tools/testing/selftests/bpf/bpf_util.h
> b/tools/testing/selftests/bpf/bpf_util.h
> index a29206ebbd13..9ad9c7595f93 100644
> --- a/tools/testing/selftests/bpf/bpf_util.h
> +++ b/tools/testing/selftests/bpf/bpf_util.h
> @@ -6,44 +6,17 @@
> #include <stdlib.h>
> #include <string.h>
> #include <errno.h>
> +#include <libbpf.h>
>
> 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 len, n, i, j = 0;
> + int possible_cpus = libbpf_num_possible_cpus();
>
> - fp = fopen(fcpu, "r");
> - if (!fp) {
> - printf("Failed to open %s: '%s'!\n", fcpu, strerror(errno));
> + if (possible_cpus <= 0) {
hmmm... so it seems that possible_cpus could be 0?
or libbpf_num_possible_cpus() should never return 0?
> + printf("Failed to get # of possible cpus: '%s'!\n",
> + strerror(-possible_cpus));
strerror(0) does not seem right.
> exit(1);
> }
> -
> - 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;
> - }
> - }
> -
> - fclose(fp);
> -
> return possible_cpus;
> }
>
> --
> 2.17.1
>
