Song Liu <songliubraving@xxxxxx> wrote on Wed [2019-Jun-05 22:51:24 -0700]:
>
>
> > On Jun 5, 2019, at 4:15 PM, Hechao Li <hechaol@xxxxxx> wrote:
> >
> > Use the newly added bpf_num_possible_cpus() in bpftool and selftests
> > and remove duplicate implementations.
> >
> > Signed-off-by: Hechao Li <hechaol@xxxxxx>
> > ---
> > 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) {
> > + printf("Failed to get # of possible cpus: '%s'!\n",
> > + strerror(-possible_cpus));
>
> This is not correct. The -possible_cpus is not errno, so we cannot
> use it with strerror().
>
> I guess we can just go with
>
> printf("Failed to get # of possible cpus!\n");
>
> Thanks,
> Song
I think it works given that libbpf_num_possible_cpus() returns -errno
on error, doesn't it?
Thanks,
Hechao
>
> > 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
> >
>
