Re: [PATCH v2 bpf-next 2/2] bpf: use libbpf_num_possible_cpus in bpftool and selftests

On Jun 6, 2019, at 9:58 AM, Hechao Li [off-list ref] wrote:

Use the newly added bpf_num_possible_cpus() in bpftool and selftests
and remove duplicate implementations.

Signed-off-by: Hechao Li <redacted>
---
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));