selftests/bpf: Add ring_buffer__consume_n test.

Commit Message

Andrea Righi April 20, 2024, 3:59 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        | 65 +++++++++++++++++++
 .../selftests/bpf/progs/test_ringbuf_n.c      | 52 +++++++++++++++
 3 files changed, 118 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_n.c

Comments

Jiri Olsa April 21, 2024, 8:11 p.m. UTC | #1

On Sat, Apr 20, 2024 at 05:59:04PM +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.
> 

SNIP

> diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> index 48c5695b7abf..7e085bfce9b5 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
> @@ -60,6 +61,7 @@ static int process_sample(void *ctx, void *data, size_t len)
>  }
>  
>  static struct test_ringbuf_map_key_lskel *skel_map_key;
> +static struct test_ringbuf_n_lskel *skel_n;

seems like there's no need for this to be static variable

>  static struct test_ringbuf_lskel *skel;
>  static struct ring_buffer *ringbuf;
>  
> @@ -326,6 +328,67 @@ 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;
> +
> +	CHECK(s->value != SAMPLE_VALUE,
> +	      "sample_value", "exp %ld, got %ld\n", SAMPLE_VALUE, s->value);

I think we should use ASSERT macros instead in the new code

> +
> +	return 0;
> +}
> +
> +static void ringbuf_n_subtest(void)
> +{
> +	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->bss->value = SAMPLE_VALUE;

skel_n ?

> +	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");
> +	}
> +

SNIP

> 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..b98b5bb20699
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> @@ -0,0 +1,52 @@
> +// 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;
> +	int seq;

seq does not seem to be checked, is it needed?

jirka

> +	long value;
> +	char comm[16];
> +};
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_RINGBUF);
> +} ringbuf SEC(".maps");
> +
> +int pid = 0;
> +long value = 0;
> +
> +/* inner state */
> +long seq = 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->seq = seq++;
> +	sample->value = value;
> +	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
> +
> +	bpf_ringbuf_submit(sample, 0);
> +
> +	return 0;
> +}
> -- 
> 2.43.0
> 
>

Andrea Righi April 25, 2024, 6:19 a.m. UTC | #2

On Sun, Apr 21, 2024 at 10:11:33PM +0200, Jiri Olsa wrote:
...
> >  static struct test_ringbuf_map_key_lskel *skel_map_key;
> > +static struct test_ringbuf_n_lskel *skel_n;
> 
> seems like there's no need for this to be static variable

Can you elaborate more? I think we want these pointers to be static to
limit the scope to this file, no?

> 
> >  static struct test_ringbuf_lskel *skel;
> >  static struct ring_buffer *ringbuf;
> >  
> > @@ -326,6 +328,67 @@ 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;
> > +
> > +	CHECK(s->value != SAMPLE_VALUE,
> > +	      "sample_value", "exp %ld, got %ld\n", SAMPLE_VALUE, s->value);
> 
> I think we should use ASSERT macros instead in the new code

Good catch, I'll change this to an ASSERT_EQ().

> 
> > +
> > +	return 0;
> > +}
> > +
> > +static void ringbuf_n_subtest(void)
> > +{
> > +	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->bss->value = SAMPLE_VALUE;
> 
> skel_n ?

Absolutely... I'm suprised that it works actually, I guess pure luck
(unluck) to reuse the old pointer and have value mapped to the same
location. Anyway, I'll fix this.

> 
> > +	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");
> > +	}
> > +
> 
> SNIP
> 
> > 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..b98b5bb20699
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> > @@ -0,0 +1,52 @@
> > +// 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;
> > +	int seq;
> 
> seq does not seem to be checked, is it needed?

seq is not used at all, I can definitely drop it.

Thanks for the review! I'll send a v2.

-Andrea

Jiri Olsa April 25, 2024, 12:23 p.m. UTC | #3

On Thu, Apr 25, 2024 at 08:19:04AM +0200, Andrea Righi wrote:
> On Sun, Apr 21, 2024 at 10:11:33PM +0200, Jiri Olsa wrote:
> ...
> > >  static struct test_ringbuf_map_key_lskel *skel_map_key;
> > > +static struct test_ringbuf_n_lskel *skel_n;
> > 
> > seems like there's no need for this to be static variable
> 
> Can you elaborate more? I think we want these pointers to be static to
> limit the scope to this file, no?

I meant to move it directly inside ringbuf_n_subtest function,
I don't see reason why it's defined outside of that function

jirka

> 
> > 
> > >  static struct test_ringbuf_lskel *skel;
> > >  static struct ring_buffer *ringbuf;
> > >  
> > > @@ -326,6 +328,67 @@ 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;
> > > +
> > > +	CHECK(s->value != SAMPLE_VALUE,
> > > +	      "sample_value", "exp %ld, got %ld\n", SAMPLE_VALUE, s->value);
> > 
> > I think we should use ASSERT macros instead in the new code
> 
> Good catch, I'll change this to an ASSERT_EQ().
> 
> > 
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static void ringbuf_n_subtest(void)
> > > +{
> > > +	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->bss->value = SAMPLE_VALUE;
> > 
> > skel_n ?
> 
> Absolutely... I'm suprised that it works actually, I guess pure luck
> (unluck) to reuse the old pointer and have value mapped to the same
> location. Anyway, I'll fix this.
> 
> > 
> > > +	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");
> > > +	}
> > > +
> > 
> > SNIP
> > 
> > > 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..b98b5bb20699
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> > > @@ -0,0 +1,52 @@
> > > +// 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;
> > > +	int seq;
> > 
> > seq does not seem to be checked, is it needed?
> 
> seq is not used at all, I can definitely drop it.
> 
> Thanks for the review! I'll send a v2.
> 
> -Andrea

Andrea Righi April 25, 2024, 2:01 p.m. UTC | #4

On Thu, Apr 25, 2024 at 02:23:30PM +0200, Jiri Olsa wrote:
> On Thu, Apr 25, 2024 at 08:19:04AM +0200, Andrea Righi wrote:
> > On Sun, Apr 21, 2024 at 10:11:33PM +0200, Jiri Olsa wrote:
> > ...
> > > >  static struct test_ringbuf_map_key_lskel *skel_map_key;
> > > > +static struct test_ringbuf_n_lskel *skel_n;
> > > 
> > > seems like there's no need for this to be static variable
> > 
> > Can you elaborate more? I think we want these pointers to be static to
> > limit the scope to this file, no?
> 
> I meant to move it directly inside ringbuf_n_subtest function,
> I don't see reason why it's defined outside of that function

Oh I see! Yeah, that makes sense, I'll send a v3 soon.

Thanks,
-Andrea

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..7e085bfce9b5 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
@@ -60,6 +61,7 @@  static int process_sample(void *ctx, void *data, size_t len)
 }
 
 static struct test_ringbuf_map_key_lskel *skel_map_key;
+static struct test_ringbuf_n_lskel *skel_n;
 static struct test_ringbuf_lskel *skel;
 static struct ring_buffer *ringbuf;
 
@@ -326,6 +328,67 @@  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;
+
+	CHECK(s->value != SAMPLE_VALUE,
+	      "sample_value", "exp %ld, got %ld\n", SAMPLE_VALUE, s->value);
+
+	return 0;
+}
+
+static void ringbuf_n_subtest(void)
+{
+	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->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 +447,8 @@  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..b98b5bb20699
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
@@ -0,0 +1,52 @@ 
+// 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;
+	int seq;
+	long value;
+	char comm[16];
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+int pid = 0;
+long value = 0;
+
+/* inner state */
+long seq = 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->seq = seq++;
+	sample->value = value;
+	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
+
+	bpf_ringbuf_submit(sample, 0);
+
+	return 0;
+}