* [PATCH v3 bpf-next 1/2] bpf: add a new API libbpf_num_possible_cpus()
2019-06-06 19:39 [PATCH v3 bpf-next 0/2] bpf: Add a new API libbpf_num_possible_cpus() Hechao Li
@ 2019-06-06 19:39 ` Hechao Li
2019-06-06 22:10 ` Andrii Nakryiko
2019-06-06 19:39 ` [PATCH v3 bpf-next 2/2] bpf: use libbpf_num_possible_cpus in bpftool and selftests Hechao Li
2019-06-06 20:26 ` [PATCH v3 bpf-next 0/2] bpf: Add a new API libbpf_num_possible_cpus() Song Liu
2 siblings, 1 reply; 5+ messages in thread
From: Hechao Li @ 2019-06-06 19:39 UTC (permalink / raw)
To: bpf; +Cc: netdev, daniel, kernel-team, Hechao Li
Adding a new API libbpf_num_possible_cpus() that helps user with
per-CPU map operations.
Signed-off-by: Hechao Li <hechaol@fb.com>
---
tools/lib/bpf/libbpf.c | 57 ++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 16 +++++++++++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 74 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ba89d9727137..06497c8a3372 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3827,3 +3827,60 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
desc->array_offset, addr);
}
}
+
+int libbpf_num_possible_cpus(void)
+{
+ static const char *fcpu = "/sys/devices/system/cpu/possible";
+ int len = 0, n = 0, il = 0, ir = 0;
+ unsigned int start = 0, end = 0;
+ static int cpus;
+ char buf[128];
+ int error = 0;
+ int fd = -1;
+
+ if (cpus > 0)
+ return cpus;
+
+ fd = open(fcpu, O_RDONLY);
+ if (fd < 0) {
+ error = errno;
+ pr_warning("Failed to open file %s: %s\n",
+ fcpu, strerror(error));
+ return -error;
+ }
+ len = read(fd, buf, sizeof(buf));
+ close(fd);
+ if (len <= 0) {
+ error = errno;
+ pr_warning("Failed to read # of possible cpus from %s: %s\n",
+ fcpu, strerror(error));
+ return -error;
+ }
+ if (len == sizeof(buf)) {
+ pr_warning("File %s size overflow\n", fcpu);
+ return -EOVERFLOW;
+ }
+ buf[len] = '\0';
+
+ for (ir = 0, cpus = 0; ir <= len; ir++) {
+ /* Each sub string separated by ',' has format \d+-\d+ or \d+ */
+ if (buf[ir] == ',' || buf[ir] == '\0') {
+ buf[ir] = '\0';
+ n = sscanf(&buf[il], "%u-%u", &start, &end);
+ if (n <= 0) {
+ pr_warning("Failed to get # CPUs from %s\n",
+ &buf[il]);
+ return -EINVAL;
+ } else if (n == 1) {
+ end = start;
+ }
+ cpus += end - start + 1;
+ il = ir + 1;
+ }
+ }
+ if (cpus <= 0) {
+ pr_warning("Invalid #CPUs %d from %s\n", cpus, fcpu);
+ return -EINVAL;
+ }
+ return cpus;
+}
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 1af0d48178c8..f5e82eb2e5d4 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -454,6 +454,22 @@ bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear);
LIBBPF_API void
bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear);
+/*
+ * A helper function to get the number of possible CPUs before looking up
+ * per-CPU maps. Negative errno is returned on failure.
+ *
+ * Example usage:
+ *
+ * int ncpus = libbpf_num_possible_cpus();
+ * if (ncpus <= 0) {
+ * // error handling
+ * }
+ * long values[ncpus];
+ * bpf_map_lookup_elem(per_cpu_map_fd, key, values);
+ *
+ */
+LIBBPF_API int libbpf_num_possible_cpus(void);
+
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 46dcda89df21..2c6d835620d2 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -172,4 +172,5 @@ LIBBPF_0.0.4 {
btf_dump__new;
btf__parse_elf;
bpf_object__load_xattr;
+ libbpf_num_possible_cpus;
} LIBBPF_0.0.3;
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v3 bpf-next 1/2] bpf: add a new API libbpf_num_possible_cpus()
2019-06-06 19:39 ` [PATCH v3 bpf-next 1/2] bpf: add " Hechao Li
@ 2019-06-06 22:10 ` Andrii Nakryiko
0 siblings, 0 replies; 5+ messages in thread
From: Andrii Nakryiko @ 2019-06-06 22:10 UTC (permalink / raw)
To: Hechao Li; +Cc: bpf, Networking, Daniel Borkmann, Kernel Team
On Thu, Jun 6, 2019 at 1:17 PM Hechao Li <hechaol@fb.com> wrote:
>
> Adding a new API libbpf_num_possible_cpus() that helps user with
> per-CPU map operations.
>
> Signed-off-by: Hechao Li <hechaol@fb.com>
> ---
> tools/lib/bpf/libbpf.c | 57 ++++++++++++++++++++++++++++++++++++++++
> tools/lib/bpf/libbpf.h | 16 +++++++++++
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 74 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index ba89d9727137..06497c8a3372 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -3827,3 +3827,60 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
> desc->array_offset, addr);
> }
> }
> +
> +int libbpf_num_possible_cpus(void)
> +{
> + static const char *fcpu = "/sys/devices/system/cpu/possible";
> + int len = 0, n = 0, il = 0, ir = 0;
> + unsigned int start = 0, end = 0;
> + static int cpus;
> + char buf[128];
> + int error = 0;
> + int fd = -1;
> +
> + if (cpus > 0)
> + return cpus;
> +
> + fd = open(fcpu, O_RDONLY);
> + if (fd < 0) {
> + error = errno;
> + pr_warning("Failed to open file %s: %s\n",
> + fcpu, strerror(error));
> + return -error;
> + }
> + len = read(fd, buf, sizeof(buf));
> + close(fd);
> + if (len <= 0) {
> + error = errno;
As Martin mentioned, you should handle len == 0 case separately, as
errno will be wrong in that case (read doesn't change errno in that
case). So something like:
error = len ? errno : EINVAL;
> + pr_warning("Failed to read # of possible cpus from %s: %s\n",
> + fcpu, strerror(error));
> + return -error;
> + }
> + if (len == sizeof(buf)) {
> + pr_warning("File %s size overflow\n", fcpu);
> + return -EOVERFLOW;
> + }
> + buf[len] = '\0';
> +
> + for (ir = 0, cpus = 0; ir <= len; ir++) {
> + /* Each sub string separated by ',' has format \d+-\d+ or \d+ */
> + if (buf[ir] == ',' || buf[ir] == '\0') {
> + buf[ir] = '\0';
> + n = sscanf(&buf[il], "%u-%u", &start, &end);
> + if (n <= 0) {
> + pr_warning("Failed to get # CPUs from %s\n",
> + &buf[il]);
> + return -EINVAL;
> + } else if (n == 1) {
> + end = start;
> + }
> + cpus += end - start + 1;
> + il = ir + 1;
> + }
> + }
> + if (cpus <= 0) {
> + pr_warning("Invalid #CPUs %d from %s\n", cpus, fcpu);
> + return -EINVAL;
> + }
> + return cpus;
> +}
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 1af0d48178c8..f5e82eb2e5d4 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -454,6 +454,22 @@ bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear);
> LIBBPF_API void
> bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear);
>
> +/*
> + * A helper function to get the number of possible CPUs before looking up
> + * per-CPU maps. Negative errno is returned on failure.
> + *
> + * Example usage:
> + *
> + * int ncpus = libbpf_num_possible_cpus();
> + * if (ncpus <= 0) {
> + * // error handling
> + * }
> + * long values[ncpus];
> + * bpf_map_lookup_elem(per_cpu_map_fd, key, values);
> + *
> + */
> +LIBBPF_API int libbpf_num_possible_cpus(void);
> +
> #ifdef __cplusplus
> } /* extern "C" */
> #endif
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 46dcda89df21..2c6d835620d2 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -172,4 +172,5 @@ LIBBPF_0.0.4 {
> btf_dump__new;
> btf__parse_elf;
> bpf_object__load_xattr;
> + libbpf_num_possible_cpus;
> } LIBBPF_0.0.3;
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v3 bpf-next 2/2] bpf: use libbpf_num_possible_cpus in bpftool and selftests
2019-06-06 19:39 [PATCH v3 bpf-next 0/2] bpf: Add a new API libbpf_num_possible_cpus() Hechao Li
2019-06-06 19:39 ` [PATCH v3 bpf-next 1/2] bpf: add " Hechao Li
@ 2019-06-06 19:39 ` Hechao Li
2019-06-06 20:26 ` [PATCH v3 bpf-next 0/2] bpf: Add a new API libbpf_num_possible_cpus() Song Liu
2 siblings, 0 replies; 5+ messages in thread
From: Hechao Li @ 2019-06-06 19:39 UTC (permalink / raw)
To: bpf; +Cc: netdev, daniel, kernel-team, Hechao Li
Use the newly added bpf_num_possible_cpus() in bpftool and selftests
and remove duplicate implementations.
Signed-off-by: Hechao Li <hechaol@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..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_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;
}
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v3 bpf-next 0/2] bpf: Add a new API libbpf_num_possible_cpus()
2019-06-06 19:39 [PATCH v3 bpf-next 0/2] bpf: Add a new API libbpf_num_possible_cpus() Hechao Li
2019-06-06 19:39 ` [PATCH v3 bpf-next 1/2] bpf: add " Hechao Li
2019-06-06 19:39 ` [PATCH v3 bpf-next 2/2] bpf: use libbpf_num_possible_cpus in bpftool and selftests Hechao Li
@ 2019-06-06 20:26 ` Song Liu
2 siblings, 0 replies; 5+ messages in thread
From: Song Liu @ 2019-06-06 20:26 UTC (permalink / raw)
To: Hechao Li; +Cc: bpf, netdev, daniel, Kernel Team
> On Jun 6, 2019, at 12:39 PM, Hechao Li <hechaol@fb.com> wrote:
>
> Getting number of possible CPUs is commonly used for per-CPU BPF maps
> and perf_event_maps. Add a new API libbpf_num_possible_cpus() that
> helps user with per-CPU related operations and remove duplicate
> implementations in bpftool and selftests.
>
> Hechao Li (2):
> bpf: add a new API libbpf_num_possible_cpus()
> bpf: use libbpf_num_possible_cpus in bpftool and selftests
For the series:
Acked-by: Song Liu <songliubraving@fb.com>
Thanks for the patch!
>
> tools/bpf/bpftool/common.c | 53 +++---------------------
> tools/lib/bpf/libbpf.c | 57 ++++++++++++++++++++++++++
> tools/lib/bpf/libbpf.h | 16 ++++++++
> tools/lib/bpf/libbpf.map | 1 +
> tools/testing/selftests/bpf/bpf_util.h | 37 +++--------------
> 5 files changed, 84 insertions(+), 80 deletions(-)
>
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 5+ messages in thread