[v5,bpf-next,2/2] bpf: use libbpf_num_possible_cpus

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index f7261fad45c1..5215e0870bcb 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: %s", strerror(-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_endian.h b/tools/testing/selftests/bpf/bpf_endian.h
index b25595ea4a78..05f036df8a4c 100644
--- a/tools/testing/selftests/bpf/bpf_endian.h
+++ b/tools/testing/selftests/bpf/bpf_endian.h
@@ -2,6 +2,7 @@ 
 #ifndef __BPF_ENDIAN__
 #define __BPF_ENDIAN__
 
+#include <linux/stddef.h>
 #include <linux/swab.h>
 
 /* LLVM's BPF target selects the endianness of the CPU
diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h
index a29206ebbd13..6231eafd4a5a 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));
 		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;
 }
 
diff --git a/tools/testing/selftests/bpf/progs/sockmap_parse_prog.c b/tools/testing/selftests/bpf/progs/sockmap_parse_prog.c
index ed3e4a551c57..9390e0244259 100644
--- a/tools/testing/selftests/bpf/progs/sockmap_parse_prog.c
+++ b/tools/testing/selftests/bpf/progs/sockmap_parse_prog.c
@@ -1,6 +1,5 @@ 
 #include <linux/bpf.h>
 #include "bpf_helpers.h"
-#include "bpf_util.h"
 #include "bpf_endian.h"
 
 int _version SEC("version") = 1;
diff --git a/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c b/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c
index 65fbfdb6cd3a..e80484d98a1a 100644
--- a/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c
+++ b/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c
@@ -1,6 +1,6 @@ 
 #include <linux/bpf.h>
+
 #include "bpf_helpers.h"
-#include "bpf_util.h"
 #include "bpf_endian.h"
 
 int _version SEC("version") = 1;
diff --git a/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c b/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c
index bdc22be46f2e..d85c874ef25e 100644
--- a/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c
+++ b/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c
@@ -1,6 +1,5 @@ 
 #include <linux/bpf.h>
 #include "bpf_helpers.h"
-#include "bpf_util.h"
 #include "bpf_endian.h"
 
 int _version SEC("version") = 1;
diff --git a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
index a295cad805d7..5cbbff416998 100644
--- a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
+++ b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
@@ -8,7 +8,6 @@ 
 #include <linux/bpf.h>
 
 #include "bpf_helpers.h"
-#include "bpf_util.h"
 
 /* Max supported length of a string with unsigned long in base 10 (pow2 - 1). */
 #define MAX_ULONG_STR_LEN 0xF
@@ -16,6 +15,10 @@ 
 /* Max supported length of sysctl value string (pow2). */
 #define MAX_VALUE_STR_LEN 0x40
 
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
 static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
 {
 	char tcp_mem_name[] = "net/ipv4/tcp_mem";