[v3] selftests/bpf: Add ring_buffer__consume_n test.

Commit Message

Andrea Righi April 25, 2024, 2:06 p.m. UTC

Add a testcase for the ring_buffer__consume_n() API.

The test produces multiple samples in a ring buffer, using a
sys_getpid() fentry prog, and consumes them from user-space in batches,
rather than consuming all of them greedily, like ring_buffer__consume()
does.

Link: https://lore.kernel.org/lkml/CAEf4BzaR4zqUpDmj44KNLdpJ=[e-mail]
Signed-off-by: Andrea Righi <[e-mail]>
---
 tools/testing/selftests/bpf/Makefile          |  2 +-
 .../selftests/bpf/prog_tests/ringbuf.c        | 64 +++++++++++++++++++
 .../selftests/bpf/progs/test_ringbuf_n.c      | 47 ++++++++++++++
 3 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_n.c

ChangeLog v2 -> v3:
 - move skel_n inside ringbuf_n_subtest()

ChangeLog v1 -> v2:
 - replace CHECK() with ASSERT_EQ()
 - fix skel -> skel_n
 - drop unused "seq" field from struct sample

Comments

Jiri Olsa April 25, 2024, 5:15 p.m. UTC | #1

On Thu, Apr 25, 2024 at 04:06:27PM +0200, Andrea Righi wrote:
> Add a testcase for the ring_buffer__consume_n() API.
> 
> The test produces multiple samples in a ring buffer, using a
> sys_getpid() fentry prog, and consumes them from user-space in batches,
> rather than consuming all of them greedily, like ring_buffer__consume()
> does.
> 
> Link: https://lore.kernel.org/lkml/CAEf4BzaR4zqUpDmj44KNLdpJ=[e-mail]
> Signed-off-by: Andrea Righi <[e-mail]>

Acked-by: Jiri Olsa <[e-mail]>

jirka

> ---
>  tools/testing/selftests/bpf/Makefile          |  2 +-
>  .../selftests/bpf/prog_tests/ringbuf.c        | 64 +++++++++++++++++++
>  .../selftests/bpf/progs/test_ringbuf_n.c      | 47 ++++++++++++++
>  3 files changed, 112 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> 
> ChangeLog v2 -> v3:
>  - move skel_n inside ringbuf_n_subtest()
> 
> ChangeLog v1 -> v2:
>  - replace CHECK() with ASSERT_EQ()
>  - fix skel -> skel_n
>  - drop unused "seq" field from struct sample
> 
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index edc73f8f5aef..6332277edeca 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -455,7 +455,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
>  LSKELS := fentry_test.c fexit_test.c fexit_sleep.c atomics.c 		\
>  	trace_printk.c trace_vprintk.c map_ptr_kern.c 			\
>  	core_kern.c core_kern_overflow.c test_ringbuf.c			\
> -	test_ringbuf_map_key.c
> +	test_ringbuf_n.c test_ringbuf_map_key.c
>  
>  # Generate both light skeleton and libbpf skeleton for these
>  LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
> diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> index 48c5695b7abf..2f064d6952f0 100644
> --- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> @@ -13,6 +13,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/ring_buffer.h>
>  #include "test_ringbuf.lskel.h"
> +#include "test_ringbuf_n.lskel.h"
>  #include "test_ringbuf_map_key.lskel.h"
>  
>  #define EDONE 7777
> @@ -326,6 +327,67 @@ static void ringbuf_subtest(void)
>  	test_ringbuf_lskel__destroy(skel);
>  }
>  
> +/*
> + * Test ring_buffer__consume_n() by producing N_TOT_SAMPLES samples in the ring
> + * buffer, via getpid(), and consuming them in chunks of N_SAMPLES.
> + */
> +#define N_TOT_SAMPLES	32
> +#define N_SAMPLES	4
> +
> +/* Sample value to verify the callback validity */
> +#define SAMPLE_VALUE	42L
> +
> +static int process_n_sample(void *ctx, void *data, size_t len)
> +{
> +	struct sample *s = data;
> +
> +	ASSERT_EQ(s->value, SAMPLE_VALUE, "sample_value");
> +
> +	return 0;
> +}
> +
> +static void ringbuf_n_subtest(void)
> +{
> +	struct test_ringbuf_n_lskel *skel_n;
> +	int err, i;
> +
> +	skel_n = test_ringbuf_n_lskel__open();
> +	if (!ASSERT_OK_PTR(skel_n, "test_ringbuf_n_lskel__open"))
> +		return;
> +
> +	skel_n->maps.ringbuf.max_entries = getpagesize();
> +	skel_n->bss->pid = getpid();
> +
> +	err = test_ringbuf_n_lskel__load(skel_n);
> +	if (!ASSERT_OK(err, "test_ringbuf_n_lskel__load"))
> +		goto cleanup;
> +
> +	ringbuf = ring_buffer__new(skel_n->maps.ringbuf.map_fd,
> +				   process_n_sample, NULL, NULL);
> +	if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
> +		goto cleanup;
> +
> +	err = test_ringbuf_n_lskel__attach(skel_n);
> +	if (!ASSERT_OK(err, "test_ringbuf_n_lskel__attach"))
> +		goto cleanup_ringbuf;
> +
> +	/* Produce N_TOT_SAMPLES samples in the ring buffer by calling getpid() */
> +	skel_n->bss->value = SAMPLE_VALUE;
> +	for (i = 0; i < N_TOT_SAMPLES; i++)
> +		syscall(__NR_getpgid);
> +
> +	/* Consume all samples from the ring buffer in batches of N_SAMPLES */
> +	for (i = 0; i < N_TOT_SAMPLES; i += err) {
> +		err = ring_buffer__consume_n(ringbuf, N_SAMPLES);
> +		ASSERT_EQ(err, N_SAMPLES, "rb_consume");
> +	}
> +
> +cleanup_ringbuf:
> +	ring_buffer__free(ringbuf);
> +cleanup:
> +	test_ringbuf_n_lskel__destroy(skel_n);
> +}
> +
>  static int process_map_key_sample(void *ctx, void *data, size_t len)
>  {
>  	struct sample *s;
> @@ -384,6 +446,8 @@ void test_ringbuf(void)
>  {
>  	if (test__start_subtest("ringbuf"))
>  		ringbuf_subtest();
> +	if (test__start_subtest("ringbuf_n"))
> +		ringbuf_n_subtest();
>  	if (test__start_subtest("ringbuf_map_key"))
>  		ringbuf_map_key_subtest();
>  }
> diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_n.c b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> new file mode 100644
> index 000000000000..8669eb42dbe0
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2024 Andrea Righi <[e-mail]>
> +
> +#include <linux/bpf.h>
> +#include <sched.h>
> +#include <unistd.h>
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_misc.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +#define TASK_COMM_LEN 16
> +
> +struct sample {
> +	int pid;
> +	long value;
> +	char comm[16];
> +};
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_RINGBUF);
> +} ringbuf SEC(".maps");
> +
> +int pid = 0;
> +long value = 0;
> +
> +SEC("fentry/" SYS_PREFIX "sys_getpgid")
> +int test_ringbuf_n(void *ctx)
> +{
> +	int cur_pid = bpf_get_current_pid_tgid() >> 32;
> +	struct sample *sample;
> +
> +	if (cur_pid != pid)
> +		return 0;
> +
> +	sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
> +	if (!sample)
> +		return 0;
> +
> +	sample->pid = pid;
> +	sample->value = value;
> +	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
> +
> +	bpf_ringbuf_submit(sample, 0);
> +
> +	return 0;
> +}
> -- 
> 2.43.0
>

Andrii Nakryiko April 25, 2024, 6:47 p.m. UTC | #2

On Thu, Apr 25, 2024 at 7:06 AM Andrea Righi <[e-mail]> wrote:
>
> Add a testcase for the ring_buffer__consume_n() API.
>
> The test produces multiple samples in a ring buffer, using a
> sys_getpid() fentry prog, and consumes them from user-space in batches,
> rather than consuming all of them greedily, like ring_buffer__consume()
> does.
>
> Link: https://lore.kernel.org/lkml/CAEf4BzaR4zqUpDmj44KNLdpJ=[e-mail]
> Signed-off-by: Andrea Righi <[e-mail]>
> ---
>  tools/testing/selftests/bpf/Makefile          |  2 +-
>  .../selftests/bpf/prog_tests/ringbuf.c        | 64 +++++++++++++++++++
>  .../selftests/bpf/progs/test_ringbuf_n.c      | 47 ++++++++++++++
>  3 files changed, 112 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_n.c
>
> ChangeLog v2 -> v3:
>  - move skel_n inside ringbuf_n_subtest()
>
> ChangeLog v1 -> v2:
>  - replace CHECK() with ASSERT_EQ()
>  - fix skel -> skel_n
>  - drop unused "seq" field from struct sample
>

[...]

> +       /* Produce N_TOT_SAMPLES samples in the ring buffer by calling getpid() */
> +       skel_n->bss->value = SAMPLE_VALUE;
> +       for (i = 0; i < N_TOT_SAMPLES; i++)
> +               syscall(__NR_getpgid);
> +
> +       /* Consume all samples from the ring buffer in batches of N_SAMPLES */
> +       for (i = 0; i < N_TOT_SAMPLES; i += err) {
> +               err = ring_buffer__consume_n(ringbuf, N_SAMPLES);
> +               ASSERT_EQ(err, N_SAMPLES, "rb_consume");

if something goes wrong and err is < 0, we might end up with a very
long loop. I changed this to:

if (!ASSERT_EQ(...))
    goto cleanup_ringbuf;

to avoid this problem

> +       }
> +
> +cleanup_ringbuf:
> +       ring_buffer__free(ringbuf);
> +cleanup:
> +       test_ringbuf_n_lskel__destroy(skel_n);
> +}
> +

[...]

Andrea Righi April 25, 2024, 8:12 p.m. UTC | #3

On Thu, Apr 25, 2024 at 11:47:07AM -0700, Andrii Nakryiko wrote:
> On Thu, Apr 25, 2024 at 7:06 AM Andrea Righi <[e-mail]> wrote:
> >
> > Add a testcase for the ring_buffer__consume_n() API.
> >
> > The test produces multiple samples in a ring buffer, using a
> > sys_getpid() fentry prog, and consumes them from user-space in batches,
> > rather than consuming all of them greedily, like ring_buffer__consume()
> > does.
> >
> > Link: https://lore.kernel.org/lkml/CAEf4BzaR4zqUpDmj44KNLdpJ=[e-mail]
> > Signed-off-by: Andrea Righi <[e-mail]>
> > ---
> >  tools/testing/selftests/bpf/Makefile          |  2 +-
> >  .../selftests/bpf/prog_tests/ringbuf.c        | 64 +++++++++++++++++++
> >  .../selftests/bpf/progs/test_ringbuf_n.c      | 47 ++++++++++++++
> >  3 files changed, 112 insertions(+), 1 deletion(-)
> >  create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> >
> > ChangeLog v2 -> v3:
> >  - move skel_n inside ringbuf_n_subtest()
> >
> > ChangeLog v1 -> v2:
> >  - replace CHECK() with ASSERT_EQ()
> >  - fix skel -> skel_n
> >  - drop unused "seq" field from struct sample
> >
> 
> [...]
> 
> > +       /* Produce N_TOT_SAMPLES samples in the ring buffer by calling getpid() */
> > +       skel_n->bss->value = SAMPLE_VALUE;
> > +       for (i = 0; i < N_TOT_SAMPLES; i++)
> > +               syscall(__NR_getpgid);
> > +
> > +       /* Consume all samples from the ring buffer in batches of N_SAMPLES */
> > +       for (i = 0; i < N_TOT_SAMPLES; i += err) {
> > +               err = ring_buffer__consume_n(ringbuf, N_SAMPLES);
> > +               ASSERT_EQ(err, N_SAMPLES, "rb_consume");
> 
> if something goes wrong and err is < 0, we might end up with a very
> long loop. I changed this to:
> 
> if (!ASSERT_EQ(...))
>     goto cleanup_ringbuf;
> 
> to avoid this problem

Looks good, tested, just in case, and it works a expected.

Thanks!
-Andrea

> 
> > +       }
> > +
> > +cleanup_ringbuf:
> > +       ring_buffer__free(ringbuf);
> > +cleanup:
> > +       test_ringbuf_n_lskel__destroy(skel_n);
> > +}
> > +
> 
> [...]

Patch

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index edc73f8f5aef..6332277edeca 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -455,7 +455,7 @@  LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
 LSKELS := fentry_test.c fexit_test.c fexit_sleep.c atomics.c 		\
 	trace_printk.c trace_vprintk.c map_ptr_kern.c 			\
 	core_kern.c core_kern_overflow.c test_ringbuf.c			\
-	test_ringbuf_map_key.c
+	test_ringbuf_n.c test_ringbuf_map_key.c
 
 # Generate both light skeleton and libbpf skeleton for these
 LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
index 48c5695b7abf..2f064d6952f0 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
@@ -13,6 +13,7 @@ 
 #include <linux/perf_event.h>
 #include <linux/ring_buffer.h>
 #include "test_ringbuf.lskel.h"
+#include "test_ringbuf_n.lskel.h"
 #include "test_ringbuf_map_key.lskel.h"
 
 #define EDONE 7777
@@ -326,6 +327,67 @@  static void ringbuf_subtest(void)
 	test_ringbuf_lskel__destroy(skel);
 }
 
+/*
+ * Test ring_buffer__consume_n() by producing N_TOT_SAMPLES samples in the ring
+ * buffer, via getpid(), and consuming them in chunks of N_SAMPLES.
+ */
+#define N_TOT_SAMPLES	32
+#define N_SAMPLES	4
+
+/* Sample value to verify the callback validity */
+#define SAMPLE_VALUE	42L
+
+static int process_n_sample(void *ctx, void *data, size_t len)
+{
+	struct sample *s = data;
+
+	ASSERT_EQ(s->value, SAMPLE_VALUE, "sample_value");
+
+	return 0;
+}
+
+static void ringbuf_n_subtest(void)
+{
+	struct test_ringbuf_n_lskel *skel_n;
+	int err, i;
+
+	skel_n = test_ringbuf_n_lskel__open();
+	if (!ASSERT_OK_PTR(skel_n, "test_ringbuf_n_lskel__open"))
+		return;
+
+	skel_n->maps.ringbuf.max_entries = getpagesize();
+	skel_n->bss->pid = getpid();
+
+	err = test_ringbuf_n_lskel__load(skel_n);
+	if (!ASSERT_OK(err, "test_ringbuf_n_lskel__load"))
+		goto cleanup;
+
+	ringbuf = ring_buffer__new(skel_n->maps.ringbuf.map_fd,
+				   process_n_sample, NULL, NULL);
+	if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
+		goto cleanup;
+
+	err = test_ringbuf_n_lskel__attach(skel_n);
+	if (!ASSERT_OK(err, "test_ringbuf_n_lskel__attach"))
+		goto cleanup_ringbuf;
+
+	/* Produce N_TOT_SAMPLES samples in the ring buffer by calling getpid() */
+	skel_n->bss->value = SAMPLE_VALUE;
+	for (i = 0; i < N_TOT_SAMPLES; i++)
+		syscall(__NR_getpgid);
+
+	/* Consume all samples from the ring buffer in batches of N_SAMPLES */
+	for (i = 0; i < N_TOT_SAMPLES; i += err) {
+		err = ring_buffer__consume_n(ringbuf, N_SAMPLES);
+		ASSERT_EQ(err, N_SAMPLES, "rb_consume");
+	}
+
+cleanup_ringbuf:
+	ring_buffer__free(ringbuf);
+cleanup:
+	test_ringbuf_n_lskel__destroy(skel_n);
+}
+
 static int process_map_key_sample(void *ctx, void *data, size_t len)
 {
 	struct sample *s;
@@ -384,6 +446,8 @@  void test_ringbuf(void)
 {
 	if (test__start_subtest("ringbuf"))
 		ringbuf_subtest();
+	if (test__start_subtest("ringbuf_n"))
+		ringbuf_n_subtest();
 	if (test__start_subtest("ringbuf_map_key"))
 		ringbuf_map_key_subtest();
 }
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_n.c b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
new file mode 100644
index 000000000000..8669eb42dbe0
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
@@ -0,0 +1,47 @@ 
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2024 Andrea Righi <[e-mail]>
+
+#include <linux/bpf.h>
+#include <sched.h>
+#include <unistd.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+#define TASK_COMM_LEN 16
+
+struct sample {
+	int pid;
+	long value;
+	char comm[16];
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+int pid = 0;
+long value = 0;
+
+SEC("fentry/" SYS_PREFIX "sys_getpgid")
+int test_ringbuf_n(void *ctx)
+{
+	int cur_pid = bpf_get_current_pid_tgid() >> 32;
+	struct sample *sample;
+
+	if (cur_pid != pid)
+		return 0;
+
+	sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
+	if (!sample)
+		return 0;
+
+	sample->pid = pid;
+	sample->value = value;
+	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
+
+	bpf_ringbuf_submit(sample, 0);
+
+	return 0;
+}