* [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper
@ 2021-12-10 14:16 Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 1/4] bpf: add bpf_strncmp helper Hou Tao
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: Hou Tao @ 2021-12-10 14:16 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Martin KaFai Lau, Yonghong Song, Daniel Borkmann,
Andrii Nakryiko, netdev, bpf, houtao1
Hi,
The motivation for introducing bpf_strncmp() helper comes from
two aspects:
(1) clang doesn't always replace strncmp() automatically
In tracing program, sometimes we need to using a home-made
strncmp() to check whether or not the file name is expected.
(2) the performance of home-made strncmp is not so good
As shown in the benchmark in patch #4, the performance of
bpf_strncmp() helper is 18% or 33% better than home-made strncmp()
under x86-64 or arm64 when the compared string length is 64. When
the string length grows to 4095, the performance win will be
179% or 600% under x86-64 or arm64.
Any comments are welcome.
Regards,
Tao
Change Log:
v2:
* rebased on bpf-next
* drop patch "selftests/bpf: factor out common helpers for benchmarks"
(suggested by Andrii)
* remove unnecessary inline functions and add comments for programs which
will be rejected by verifier in patch 4 (suggested by Andrii)
* rename variables used in will-fail programs to clarify the purposes.
v1: https://lore.kernel.org/bpf/20211130142215.1237217-1-houtao1@huawei.com
* change API to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
* add benchmark refactor and benchmark between bpf_strncmp() and strncmp()
RFC: https://lore.kernel.org/bpf/20211106132822.1396621-1-houtao1@huawei.com/
Hou Tao (4):
bpf: add bpf_strncmp helper
selftests/bpf: fix checkpatch error on empty function parameter
selftests/bpf: add benchmark for bpf_strncmp() helper
selftests/bpf: add test cases for bpf_strncmp()
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 11 ++
kernel/bpf/helpers.c | 16 ++
tools/include/uapi/linux/bpf.h | 11 ++
tools/testing/selftests/bpf/Makefile | 4 +-
tools/testing/selftests/bpf/bench.c | 8 +-
tools/testing/selftests/bpf/bench.h | 9 +-
.../selftests/bpf/benchs/bench_count.c | 2 +-
.../selftests/bpf/benchs/bench_rename.c | 16 +-
.../selftests/bpf/benchs/bench_ringbufs.c | 14 +-
.../selftests/bpf/benchs/bench_strncmp.c | 161 +++++++++++++++++
.../selftests/bpf/benchs/bench_trigger.c | 24 +--
.../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++
.../selftests/bpf/prog_tests/test_strncmp.c | 167 ++++++++++++++++++
.../selftests/bpf/progs/strncmp_bench.c | 50 ++++++
.../selftests/bpf/progs/strncmp_test.c | 54 ++++++
16 files changed, 526 insertions(+), 34 deletions(-)
create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c
create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
create mode 100644 tools/testing/selftests/bpf/prog_tests/test_strncmp.c
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_test.c
--
2.29.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH bpf-next v2 1/4] bpf: add bpf_strncmp helper
2021-12-10 14:16 [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Hou Tao
@ 2021-12-10 14:16 ` Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 2/4] selftests/bpf: fix checkpatch error on empty function parameter Hou Tao
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Hou Tao @ 2021-12-10 14:16 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Martin KaFai Lau, Yonghong Song, Daniel Borkmann,
Andrii Nakryiko, netdev, bpf, houtao1
The helper compares two strings: one string is a null-terminated
read-only string, and another string has const max storage size
but doesn't need to be null-terminated. It can be used to compare
file name in tracing or LSM program.
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 11 +++++++++++
kernel/bpf/helpers.c | 16 ++++++++++++++++
tools/include/uapi/linux/bpf.h | 11 +++++++++++
4 files changed, 39 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8bbf08fbab66..6b7c533ba249 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2173,6 +2173,7 @@ extern const struct bpf_func_proto bpf_sk_getsockopt_proto;
extern const struct bpf_func_proto bpf_kallsyms_lookup_name_proto;
extern const struct bpf_func_proto bpf_find_vma_proto;
extern const struct bpf_func_proto bpf_loop_proto;
+extern const struct bpf_func_proto bpf_strncmp_proto;
const struct bpf_func_proto *tracing_prog_func_proto(
enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c26871263f1f..2820c77e4846 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4983,6 +4983,16 @@ union bpf_attr {
* Return
* The number of loops performed, **-EINVAL** for invalid **flags**,
* **-E2BIG** if **nr_loops** exceeds the maximum number of loops.
+ *
+ * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
+ * Description
+ * Do strncmp() between **s1** and **s2**. **s1** doesn't need
+ * to be null-terminated and **s1_sz** is the maximum storage
+ * size of **s1**. **s2** must be a read-only string.
+ * Return
+ * An integer less than, equal to, or greater than zero
+ * if the first **s1_sz** bytes of **s1** is found to be
+ * less than, to match, or be greater than **s2**.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5167,6 +5177,7 @@ union bpf_attr {
FN(kallsyms_lookup_name), \
FN(find_vma), \
FN(loop), \
+ FN(strncmp), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 52188004a9c3..2b035c03624f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -565,6 +565,20 @@ const struct bpf_func_proto bpf_strtoul_proto = {
};
#endif
+BPF_CALL_3(bpf_strncmp, const char *, s1, u32, s1_sz, const char *, s2)
+{
+ return strncmp(s1, s2, s1_sz);
+}
+
+const struct bpf_func_proto bpf_strncmp_proto = {
+ .func = bpf_strncmp,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_MEM,
+ .arg2_type = ARG_CONST_SIZE,
+ .arg3_type = ARG_PTR_TO_CONST_STR,
+};
+
BPF_CALL_4(bpf_get_ns_current_pid_tgid, u64, dev, u64, ino,
struct bpf_pidns_info *, nsdata, u32, size)
{
@@ -1380,6 +1394,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_for_each_map_elem_proto;
case BPF_FUNC_loop:
return &bpf_loop_proto;
+ case BPF_FUNC_strncmp:
+ return &bpf_strncmp_proto;
default:
break;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c26871263f1f..2820c77e4846 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4983,6 +4983,16 @@ union bpf_attr {
* Return
* The number of loops performed, **-EINVAL** for invalid **flags**,
* **-E2BIG** if **nr_loops** exceeds the maximum number of loops.
+ *
+ * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
+ * Description
+ * Do strncmp() between **s1** and **s2**. **s1** doesn't need
+ * to be null-terminated and **s1_sz** is the maximum storage
+ * size of **s1**. **s2** must be a read-only string.
+ * Return
+ * An integer less than, equal to, or greater than zero
+ * if the first **s1_sz** bytes of **s1** is found to be
+ * less than, to match, or be greater than **s2**.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5167,6 +5177,7 @@ union bpf_attr {
FN(kallsyms_lookup_name), \
FN(find_vma), \
FN(loop), \
+ FN(strncmp), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH bpf-next v2 2/4] selftests/bpf: fix checkpatch error on empty function parameter
2021-12-10 14:16 [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 1/4] bpf: add bpf_strncmp helper Hou Tao
@ 2021-12-10 14:16 ` Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 3/4] selftests/bpf: add benchmark for bpf_strncmp() helper Hou Tao
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Hou Tao @ 2021-12-10 14:16 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Martin KaFai Lau, Yonghong Song, Daniel Borkmann,
Andrii Nakryiko, netdev, bpf, houtao1
Fix checkpatch error: "ERROR: Bad function definition - void foo()
should probably be void foo(void)". Most replacements are done by
the following command:
sed -i 's#\([a-z]\)()$#\1(void)#g' testing/selftests/bpf/benchs/*.c
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
tools/testing/selftests/bpf/bench.c | 2 +-
tools/testing/selftests/bpf/bench.h | 9 +++----
.../selftests/bpf/benchs/bench_count.c | 2 +-
.../selftests/bpf/benchs/bench_rename.c | 16 ++++++-------
.../selftests/bpf/benchs/bench_ringbufs.c | 14 +++++------
.../selftests/bpf/benchs/bench_trigger.c | 24 +++++++++----------
6 files changed, 34 insertions(+), 33 deletions(-)
diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c
index 3d6082b97a56..ffe5752f3324 100644
--- a/tools/testing/selftests/bpf/bench.c
+++ b/tools/testing/selftests/bpf/bench.c
@@ -39,7 +39,7 @@ static int bump_memlock_rlimit(void)
return setrlimit(RLIMIT_MEMLOCK, &rlim_new);
}
-void setup_libbpf()
+void setup_libbpf(void)
{
int err;
diff --git a/tools/testing/selftests/bpf/bench.h b/tools/testing/selftests/bpf/bench.h
index 50785503756b..fb3e213df3dc 100644
--- a/tools/testing/selftests/bpf/bench.h
+++ b/tools/testing/selftests/bpf/bench.h
@@ -38,8 +38,8 @@ struct bench_res {
struct bench {
const char *name;
- void (*validate)();
- void (*setup)();
+ void (*validate)(void);
+ void (*setup)(void);
void *(*producer_thread)(void *ctx);
void *(*consumer_thread)(void *ctx);
void (*measure)(struct bench_res* res);
@@ -54,7 +54,7 @@ struct counter {
extern struct env env;
extern const struct bench *bench;
-void setup_libbpf();
+void setup_libbpf(void);
void hits_drops_report_progress(int iter, struct bench_res *res, long delta_ns);
void hits_drops_report_final(struct bench_res res[], int res_cnt);
void false_hits_report_progress(int iter, struct bench_res *res, long delta_ns);
@@ -62,7 +62,8 @@ void false_hits_report_final(struct bench_res res[], int res_cnt);
void ops_report_progress(int iter, struct bench_res *res, long delta_ns);
void ops_report_final(struct bench_res res[], int res_cnt);
-static inline __u64 get_time_ns() {
+static inline __u64 get_time_ns(void)
+{
struct timespec t;
clock_gettime(CLOCK_MONOTONIC, &t);
diff --git a/tools/testing/selftests/bpf/benchs/bench_count.c b/tools/testing/selftests/bpf/benchs/bench_count.c
index befba7a82643..078972ce208e 100644
--- a/tools/testing/selftests/bpf/benchs/bench_count.c
+++ b/tools/testing/selftests/bpf/benchs/bench_count.c
@@ -36,7 +36,7 @@ static struct count_local_ctx {
struct counter *hits;
} count_local_ctx;
-static void count_local_setup()
+static void count_local_setup(void)
{
struct count_local_ctx *ctx = &count_local_ctx;
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c
index c7ec114eca56..3c203b6d6a6e 100644
--- a/tools/testing/selftests/bpf/benchs/bench_rename.c
+++ b/tools/testing/selftests/bpf/benchs/bench_rename.c
@@ -11,7 +11,7 @@ static struct ctx {
int fd;
} ctx;
-static void validate()
+static void validate(void)
{
if (env.producer_cnt != 1) {
fprintf(stderr, "benchmark doesn't support multi-producer!\n");
@@ -43,7 +43,7 @@ static void measure(struct bench_res *res)
res->hits = atomic_swap(&ctx.hits.value, 0);
}
-static void setup_ctx()
+static void setup_ctx(void)
{
setup_libbpf();
@@ -71,36 +71,36 @@ static void attach_bpf(struct bpf_program *prog)
}
}
-static void setup_base()
+static void setup_base(void)
{
setup_ctx();
}
-static void setup_kprobe()
+static void setup_kprobe(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.prog1);
}
-static void setup_kretprobe()
+static void setup_kretprobe(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.prog2);
}
-static void setup_rawtp()
+static void setup_rawtp(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.prog3);
}
-static void setup_fentry()
+static void setup_fentry(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.prog4);
}
-static void setup_fexit()
+static void setup_fexit(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.prog5);
diff --git a/tools/testing/selftests/bpf/benchs/bench_ringbufs.c b/tools/testing/selftests/bpf/benchs/bench_ringbufs.c
index 52d4a2f91dbd..da8593b3494a 100644
--- a/tools/testing/selftests/bpf/benchs/bench_ringbufs.c
+++ b/tools/testing/selftests/bpf/benchs/bench_ringbufs.c
@@ -88,12 +88,12 @@ const struct argp bench_ringbufs_argp = {
static struct counter buf_hits;
-static inline void bufs_trigger_batch()
+static inline void bufs_trigger_batch(void)
{
(void)syscall(__NR_getpgid);
}
-static void bufs_validate()
+static void bufs_validate(void)
{
if (env.consumer_cnt != 1) {
fprintf(stderr, "rb-libbpf benchmark doesn't support multi-consumer!\n");
@@ -132,7 +132,7 @@ static void ringbuf_libbpf_measure(struct bench_res *res)
res->drops = atomic_swap(&ctx->skel->bss->dropped, 0);
}
-static struct ringbuf_bench *ringbuf_setup_skeleton()
+static struct ringbuf_bench *ringbuf_setup_skeleton(void)
{
struct ringbuf_bench *skel;
@@ -167,7 +167,7 @@ static int buf_process_sample(void *ctx, void *data, size_t len)
return 0;
}
-static void ringbuf_libbpf_setup()
+static void ringbuf_libbpf_setup(void)
{
struct ringbuf_libbpf_ctx *ctx = &ringbuf_libbpf_ctx;
struct bpf_link *link;
@@ -223,7 +223,7 @@ static void ringbuf_custom_measure(struct bench_res *res)
res->drops = atomic_swap(&ctx->skel->bss->dropped, 0);
}
-static void ringbuf_custom_setup()
+static void ringbuf_custom_setup(void)
{
struct ringbuf_custom_ctx *ctx = &ringbuf_custom_ctx;
const size_t page_size = getpagesize();
@@ -352,7 +352,7 @@ static void perfbuf_measure(struct bench_res *res)
res->drops = atomic_swap(&ctx->skel->bss->dropped, 0);
}
-static struct perfbuf_bench *perfbuf_setup_skeleton()
+static struct perfbuf_bench *perfbuf_setup_skeleton(void)
{
struct perfbuf_bench *skel;
@@ -390,7 +390,7 @@ perfbuf_process_sample_raw(void *input_ctx, int cpu,
return LIBBPF_PERF_EVENT_CONT;
}
-static void perfbuf_libbpf_setup()
+static void perfbuf_libbpf_setup(void)
{
struct perfbuf_libbpf_ctx *ctx = &perfbuf_libbpf_ctx;
struct perf_event_attr attr;
diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c
index 049a5ad56f65..7f957c55a3ca 100644
--- a/tools/testing/selftests/bpf/benchs/bench_trigger.c
+++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c
@@ -11,7 +11,7 @@ static struct trigger_ctx {
static struct counter base_hits;
-static void trigger_validate()
+static void trigger_validate(void)
{
if (env.consumer_cnt != 1) {
fprintf(stderr, "benchmark doesn't support multi-consumer!\n");
@@ -45,7 +45,7 @@ static void trigger_measure(struct bench_res *res)
res->hits = atomic_swap(&ctx.skel->bss->hits, 0);
}
-static void setup_ctx()
+static void setup_ctx(void)
{
setup_libbpf();
@@ -67,37 +67,37 @@ static void attach_bpf(struct bpf_program *prog)
}
}
-static void trigger_tp_setup()
+static void trigger_tp_setup(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.bench_trigger_tp);
}
-static void trigger_rawtp_setup()
+static void trigger_rawtp_setup(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.bench_trigger_raw_tp);
}
-static void trigger_kprobe_setup()
+static void trigger_kprobe_setup(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.bench_trigger_kprobe);
}
-static void trigger_fentry_setup()
+static void trigger_fentry_setup(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.bench_trigger_fentry);
}
-static void trigger_fentry_sleep_setup()
+static void trigger_fentry_sleep_setup(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.bench_trigger_fentry_sleep);
}
-static void trigger_fmodret_setup()
+static void trigger_fmodret_setup(void)
{
setup_ctx();
attach_bpf(ctx.skel->progs.bench_trigger_fmodret);
@@ -183,22 +183,22 @@ static void usetup(bool use_retprobe, bool use_nop)
ctx.skel->links.bench_trigger_uprobe = link;
}
-static void uprobe_setup_with_nop()
+static void uprobe_setup_with_nop(void)
{
usetup(false, true);
}
-static void uretprobe_setup_with_nop()
+static void uretprobe_setup_with_nop(void)
{
usetup(true, true);
}
-static void uprobe_setup_without_nop()
+static void uprobe_setup_without_nop(void)
{
usetup(false, false);
}
-static void uretprobe_setup_without_nop()
+static void uretprobe_setup_without_nop(void)
{
usetup(true, false);
}
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH bpf-next v2 3/4] selftests/bpf: add benchmark for bpf_strncmp() helper
2021-12-10 14:16 [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 1/4] bpf: add bpf_strncmp helper Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 2/4] selftests/bpf: fix checkpatch error on empty function parameter Hou Tao
@ 2021-12-10 14:16 ` Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 4/4] selftests/bpf: add test cases for bpf_strncmp() Hou Tao
2021-12-12 1:50 ` [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Alexei Starovoitov
4 siblings, 0 replies; 6+ messages in thread
From: Hou Tao @ 2021-12-10 14:16 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Martin KaFai Lau, Yonghong Song, Daniel Borkmann,
Andrii Nakryiko, netdev, bpf, houtao1
Add benchmark to compare the performance between home-made strncmp()
in bpf program and bpf_strncmp() helper. In summary, the performance
win of bpf_strncmp() under x86-64 is greater than 18% when the compared
string length is greater than 64, and is 179% when the length is 4095.
Under arm64 the performance win is even bigger: 33% when the length
is greater than 64 and 600% when the length is 4095.
The following is the details:
no-helper-X: use home-made strncmp() to compare X-sized string
helper-Y: use bpf_strncmp() to compare Y-sized string
Under x86-64:
no-helper-1 3.504 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-1 3.347 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-8 3.357 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-8 3.307 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-32 3.064 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-32 3.253 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-64 2.563 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-64 3.040 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-128 1.975 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-128 2.641 ± 0.000M/s (drops 0.000 ± 0.000M/s)
no-helper-512 0.759 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-512 1.574 ± 0.000M/s (drops 0.000 ± 0.000M/s)
no-helper-2048 0.329 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s)
no-helper-4095 0.117 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-4095 0.327 ± 0.000M/s (drops 0.000 ± 0.000M/s)
Under arm64:
no-helper-1 2.806 ± 0.004M/s (drops 0.000 ± 0.000M/s)
helper-1 2.819 ± 0.002M/s (drops 0.000 ± 0.000M/s)
no-helper-8 2.797 ± 0.109M/s (drops 0.000 ± 0.000M/s)
helper-8 2.786 ± 0.025M/s (drops 0.000 ± 0.000M/s)
no-helper-32 2.399 ± 0.011M/s (drops 0.000 ± 0.000M/s)
helper-32 2.703 ± 0.002M/s (drops 0.000 ± 0.000M/s)
no-helper-64 2.020 ± 0.015M/s (drops 0.000 ± 0.000M/s)
helper-64 2.702 ± 0.073M/s (drops 0.000 ± 0.000M/s)
no-helper-128 1.604 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-128 2.516 ± 0.002M/s (drops 0.000 ± 0.000M/s)
no-helper-512 0.699 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-512 2.106 ± 0.003M/s (drops 0.000 ± 0.000M/s)
no-helper-2048 0.215 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-2048 1.223 ± 0.003M/s (drops 0.000 ± 0.000M/s)
no-helper-4095 0.112 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-4095 0.796 ± 0.000M/s (drops 0.000 ± 0.000M/s)
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
tools/testing/selftests/bpf/Makefile | 4 +-
tools/testing/selftests/bpf/bench.c | 6 +
.../selftests/bpf/benchs/bench_strncmp.c | 161 ++++++++++++++++++
.../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++
.../selftests/bpf/progs/strncmp_bench.c | 50 ++++++
5 files changed, 232 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c
create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index e38626fe3f5d..67ebf6be86f1 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -537,6 +537,7 @@ $(OUTPUT)/bench_ringbufs.o: $(OUTPUT)/ringbuf_bench.skel.h \
$(OUTPUT)/perfbuf_bench.skel.h
$(OUTPUT)/bench_bloom_filter_map.o: $(OUTPUT)/bloom_filter_bench.skel.h
$(OUTPUT)/bench_bpf_loop.o: $(OUTPUT)/bpf_loop_bench.skel.h
+$(OUTPUT)/bench_strncmp.o: $(OUTPUT)/strncmp_bench.skel.h
$(OUTPUT)/bench.o: bench.h testing_helpers.h $(BPFOBJ)
$(OUTPUT)/bench: LDLIBS += -lm
$(OUTPUT)/bench: $(OUTPUT)/bench.o \
@@ -547,7 +548,8 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o \
$(OUTPUT)/bench_trigger.o \
$(OUTPUT)/bench_ringbufs.o \
$(OUTPUT)/bench_bloom_filter_map.o \
- $(OUTPUT)/bench_bpf_loop.o
+ $(OUTPUT)/bench_bpf_loop.o \
+ $(OUTPUT)/bench_strncmp.o
$(call msg,BINARY,,$@)
$(Q)$(CC) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@
diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c
index ffe5752f3324..bbb42e2cee0c 100644
--- a/tools/testing/selftests/bpf/bench.c
+++ b/tools/testing/selftests/bpf/bench.c
@@ -205,11 +205,13 @@ static const struct argp_option opts[] = {
extern struct argp bench_ringbufs_argp;
extern struct argp bench_bloom_map_argp;
extern struct argp bench_bpf_loop_argp;
+extern struct argp bench_strncmp_argp;
static const struct argp_child bench_parsers[] = {
{ &bench_ringbufs_argp, 0, "Ring buffers benchmark", 0 },
{ &bench_bloom_map_argp, 0, "Bloom filter map benchmark", 0 },
{ &bench_bpf_loop_argp, 0, "bpf_loop helper benchmark", 0 },
+ { &bench_strncmp_argp, 0, "bpf_strncmp helper benchmark", 0 },
{},
};
@@ -409,6 +411,8 @@ extern const struct bench bench_bloom_false_positive;
extern const struct bench bench_hashmap_without_bloom;
extern const struct bench bench_hashmap_with_bloom;
extern const struct bench bench_bpf_loop;
+extern const struct bench bench_strncmp_no_helper;
+extern const struct bench bench_strncmp_helper;
static const struct bench *benchs[] = {
&bench_count_global,
@@ -441,6 +445,8 @@ static const struct bench *benchs[] = {
&bench_hashmap_without_bloom,
&bench_hashmap_with_bloom,
&bench_bpf_loop,
+ &bench_strncmp_no_helper,
+ &bench_strncmp_helper,
};
static void setup_benchmark()
diff --git a/tools/testing/selftests/bpf/benchs/bench_strncmp.c b/tools/testing/selftests/bpf/benchs/bench_strncmp.c
new file mode 100644
index 000000000000..494b591c0289
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/bench_strncmp.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <argp.h>
+#include "bench.h"
+#include "strncmp_bench.skel.h"
+
+static struct strncmp_ctx {
+ struct strncmp_bench *skel;
+} ctx;
+
+static struct strncmp_args {
+ u32 cmp_str_len;
+} args = {
+ .cmp_str_len = 32,
+};
+
+enum {
+ ARG_CMP_STR_LEN = 5000,
+};
+
+static const struct argp_option opts[] = {
+ { "cmp-str-len", ARG_CMP_STR_LEN, "CMP_STR_LEN", 0,
+ "Set the length of compared string" },
+ {},
+};
+
+static error_t strncmp_parse_arg(int key, char *arg, struct argp_state *state)
+{
+ switch (key) {
+ case ARG_CMP_STR_LEN:
+ args.cmp_str_len = strtoul(arg, NULL, 10);
+ if (!args.cmp_str_len ||
+ args.cmp_str_len >= sizeof(ctx.skel->bss->str)) {
+ fprintf(stderr, "Invalid cmp str len (limit %zu)\n",
+ sizeof(ctx.skel->bss->str));
+ argp_usage(state);
+ }
+ break;
+ default:
+ return ARGP_ERR_UNKNOWN;
+ }
+
+ return 0;
+}
+
+const struct argp bench_strncmp_argp = {
+ .options = opts,
+ .parser = strncmp_parse_arg,
+};
+
+static void strncmp_validate(void)
+{
+ if (env.consumer_cnt != 1) {
+ fprintf(stderr, "strncmp benchmark doesn't support multi-consumer!\n");
+ exit(1);
+ }
+}
+
+static void strncmp_setup(void)
+{
+ int err;
+ char *target;
+ size_t i, sz;
+
+ sz = sizeof(ctx.skel->rodata->target);
+ if (!sz || sz < sizeof(ctx.skel->bss->str)) {
+ fprintf(stderr, "invalid string size (target %zu, src %zu)\n",
+ sz, sizeof(ctx.skel->bss->str));
+ exit(1);
+ }
+
+ setup_libbpf();
+
+ ctx.skel = strncmp_bench__open();
+ if (!ctx.skel) {
+ fprintf(stderr, "failed to open skeleton\n");
+ exit(1);
+ }
+
+ srandom(time(NULL));
+ target = ctx.skel->rodata->target;
+ for (i = 0; i < sz - 1; i++)
+ target[i] = '1' + random() % 9;
+ target[sz - 1] = '\0';
+
+ ctx.skel->rodata->cmp_str_len = args.cmp_str_len;
+
+ memcpy(ctx.skel->bss->str, target, args.cmp_str_len);
+ ctx.skel->bss->str[args.cmp_str_len] = '\0';
+ /* Make bss->str < rodata->target */
+ ctx.skel->bss->str[args.cmp_str_len - 1] -= 1;
+
+ err = strncmp_bench__load(ctx.skel);
+ if (err) {
+ fprintf(stderr, "failed to load skeleton\n");
+ strncmp_bench__destroy(ctx.skel);
+ exit(1);
+ }
+}
+
+static void strncmp_attach_prog(struct bpf_program *prog)
+{
+ struct bpf_link *link;
+
+ link = bpf_program__attach(prog);
+ if (!link) {
+ fprintf(stderr, "failed to attach program!\n");
+ exit(1);
+ }
+}
+
+static void strncmp_no_helper_setup(void)
+{
+ strncmp_setup();
+ strncmp_attach_prog(ctx.skel->progs.strncmp_no_helper);
+}
+
+static void strncmp_helper_setup(void)
+{
+ strncmp_setup();
+ strncmp_attach_prog(ctx.skel->progs.strncmp_helper);
+}
+
+static void *strncmp_producer(void *ctx)
+{
+ while (true)
+ (void)syscall(__NR_getpgid);
+ return NULL;
+}
+
+static void *strncmp_consumer(void *ctx)
+{
+ return NULL;
+}
+
+static void strncmp_measure(struct bench_res *res)
+{
+ res->hits = atomic_swap(&ctx.skel->bss->hits, 0);
+}
+
+const struct bench bench_strncmp_no_helper = {
+ .name = "strncmp-no-helper",
+ .validate = strncmp_validate,
+ .setup = strncmp_no_helper_setup,
+ .producer_thread = strncmp_producer,
+ .consumer_thread = strncmp_consumer,
+ .measure = strncmp_measure,
+ .report_progress = hits_drops_report_progress,
+ .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_strncmp_helper = {
+ .name = "strncmp-helper",
+ .validate = strncmp_validate,
+ .setup = strncmp_helper_setup,
+ .producer_thread = strncmp_producer,
+ .consumer_thread = strncmp_consumer,
+ .measure = strncmp_measure,
+ .report_progress = hits_drops_report_progress,
+ .report_final = hits_drops_report_final,
+};
diff --git a/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh b/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
new file mode 100755
index 000000000000..142697284b45
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source ./benchs/run_common.sh
+
+set -eufo pipefail
+
+for s in 1 8 64 512 2048 4095; do
+ for b in no-helper helper; do
+ summarize ${b}-${s} "$($RUN_BENCH --cmp-str-len=$s strncmp-${b})"
+ done
+done
diff --git a/tools/testing/selftests/bpf/progs/strncmp_bench.c b/tools/testing/selftests/bpf/progs/strncmp_bench.c
new file mode 100644
index 000000000000..18373a7df76e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/strncmp_bench.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <linux/types.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#define STRNCMP_STR_SZ 4096
+
+/* Will be updated by benchmark before program loading */
+const volatile unsigned int cmp_str_len = 1;
+const char target[STRNCMP_STR_SZ];
+
+long hits = 0;
+char str[STRNCMP_STR_SZ];
+
+char _license[] SEC("license") = "GPL";
+
+static __always_inline int local_strncmp(const char *s1, unsigned int sz,
+ const char *s2)
+{
+ int ret = 0;
+ unsigned int i;
+
+ for (i = 0; i < sz; i++) {
+ /* E.g. 0xff > 0x31 */
+ ret = (unsigned char)s1[i] - (unsigned char)s2[i];
+ if (ret || !s1[i])
+ break;
+ }
+
+ return ret;
+}
+
+SEC("tp/syscalls/sys_enter_getpgid")
+int strncmp_no_helper(void *ctx)
+{
+ if (local_strncmp(str, cmp_str_len + 1, target) < 0)
+ __sync_add_and_fetch(&hits, 1);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_getpgid")
+int strncmp_helper(void *ctx)
+{
+ if (bpf_strncmp(str, cmp_str_len + 1, target) < 0)
+ __sync_add_and_fetch(&hits, 1);
+ return 0;
+}
+
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH bpf-next v2 4/4] selftests/bpf: add test cases for bpf_strncmp()
2021-12-10 14:16 [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Hou Tao
` (2 preceding siblings ...)
2021-12-10 14:16 ` [PATCH bpf-next v2 3/4] selftests/bpf: add benchmark for bpf_strncmp() helper Hou Tao
@ 2021-12-10 14:16 ` Hou Tao
2021-12-12 1:50 ` [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Alexei Starovoitov
4 siblings, 0 replies; 6+ messages in thread
From: Hou Tao @ 2021-12-10 14:16 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Martin KaFai Lau, Yonghong Song, Daniel Borkmann,
Andrii Nakryiko, netdev, bpf, houtao1
Four test cases are added:
(1) ensure the return value is expected
(2) ensure no const string size is rejected
(3) ensure writable target is rejected
(4) ensure no null-terminated target is rejected
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
.../selftests/bpf/prog_tests/test_strncmp.c | 167 ++++++++++++++++++
.../selftests/bpf/progs/strncmp_test.c | 54 ++++++
2 files changed, 221 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/test_strncmp.c
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_test.c
diff --git a/tools/testing/selftests/bpf/prog_tests/test_strncmp.c b/tools/testing/selftests/bpf/prog_tests/test_strncmp.c
new file mode 100644
index 000000000000..b57a3009465f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_strncmp.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <test_progs.h>
+#include "strncmp_test.skel.h"
+
+static int trigger_strncmp(const struct strncmp_test *skel)
+{
+ int cmp;
+
+ usleep(1);
+
+ cmp = skel->bss->cmp_ret;
+ if (cmp > 0)
+ return 1;
+ if (cmp < 0)
+ return -1;
+ return 0;
+}
+
+/*
+ * Compare str and target after making str[i] != target[i].
+ * When exp is -1, make str[i] < target[i] and delta = -1.
+ */
+static void strncmp_full_str_cmp(struct strncmp_test *skel, const char *name,
+ int exp)
+{
+ size_t nr = sizeof(skel->bss->str);
+ char *str = skel->bss->str;
+ int delta = exp;
+ int got;
+ size_t i;
+
+ memcpy(str, skel->rodata->target, nr);
+ for (i = 0; i < nr - 1; i++) {
+ str[i] += delta;
+
+ got = trigger_strncmp(skel);
+ ASSERT_EQ(got, exp, name);
+
+ str[i] -= delta;
+ }
+}
+
+static void test_strncmp_ret(void)
+{
+ struct strncmp_test *skel;
+ struct bpf_program *prog;
+ int err, got;
+
+ skel = strncmp_test__open();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ bpf_object__for_each_program(prog, skel->obj)
+ bpf_program__set_autoload(prog, false);
+
+ bpf_program__set_autoload(skel->progs.do_strncmp, true);
+
+ err = strncmp_test__load(skel);
+ if (!ASSERT_EQ(err, 0, "strncmp_test load"))
+ goto out;
+
+ err = strncmp_test__attach(skel);
+ if (!ASSERT_EQ(err, 0, "strncmp_test attach"))
+ goto out;
+
+ skel->bss->target_pid = getpid();
+
+ /* Empty str */
+ skel->bss->str[0] = '\0';
+ got = trigger_strncmp(skel);
+ ASSERT_EQ(got, -1, "strncmp: empty str");
+
+ /* Same string */
+ memcpy(skel->bss->str, skel->rodata->target, sizeof(skel->bss->str));
+ got = trigger_strncmp(skel);
+ ASSERT_EQ(got, 0, "strncmp: same str");
+
+ /* Not-null-termainted string */
+ memcpy(skel->bss->str, skel->rodata->target, sizeof(skel->bss->str));
+ skel->bss->str[sizeof(skel->bss->str) - 1] = 'A';
+ got = trigger_strncmp(skel);
+ ASSERT_EQ(got, 1, "strncmp: not-null-term str");
+
+ strncmp_full_str_cmp(skel, "strncmp: less than", -1);
+ strncmp_full_str_cmp(skel, "strncmp: greater than", 1);
+out:
+ strncmp_test__destroy(skel);
+}
+
+static void test_strncmp_bad_not_const_str_size(void)
+{
+ struct strncmp_test *skel;
+ struct bpf_program *prog;
+ int err;
+
+ skel = strncmp_test__open();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ bpf_object__for_each_program(prog, skel->obj)
+ bpf_program__set_autoload(prog, false);
+
+ bpf_program__set_autoload(skel->progs.strncmp_bad_not_const_str_size,
+ true);
+
+ err = strncmp_test__load(skel);
+ ASSERT_ERR(err, "strncmp_test load bad_not_const_str_size");
+
+ strncmp_test__destroy(skel);
+}
+
+static void test_strncmp_bad_writable_target(void)
+{
+ struct strncmp_test *skel;
+ struct bpf_program *prog;
+ int err;
+
+ skel = strncmp_test__open();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ bpf_object__for_each_program(prog, skel->obj)
+ bpf_program__set_autoload(prog, false);
+
+ bpf_program__set_autoload(skel->progs.strncmp_bad_writable_target,
+ true);
+
+ err = strncmp_test__load(skel);
+ ASSERT_ERR(err, "strncmp_test load bad_writable_target");
+
+ strncmp_test__destroy(skel);
+}
+
+static void test_strncmp_bad_not_null_term_target(void)
+{
+ struct strncmp_test *skel;
+ struct bpf_program *prog;
+ int err;
+
+ skel = strncmp_test__open();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ bpf_object__for_each_program(prog, skel->obj)
+ bpf_program__set_autoload(prog, false);
+
+ bpf_program__set_autoload(skel->progs.strncmp_bad_not_null_term_target,
+ true);
+
+ err = strncmp_test__load(skel);
+ ASSERT_ERR(err, "strncmp_test load bad_not_null_term_target");
+
+ strncmp_test__destroy(skel);
+}
+
+void test_test_strncmp(void)
+{
+ if (test__start_subtest("strncmp_ret"))
+ test_strncmp_ret();
+ if (test__start_subtest("strncmp_bad_not_const_str_size"))
+ test_strncmp_bad_not_const_str_size();
+ if (test__start_subtest("strncmp_bad_writable_target"))
+ test_strncmp_bad_writable_target();
+ if (test__start_subtest("strncmp_bad_not_null_term_target"))
+ test_strncmp_bad_not_null_term_target();
+}
diff --git a/tools/testing/selftests/bpf/progs/strncmp_test.c b/tools/testing/selftests/bpf/progs/strncmp_test.c
new file mode 100644
index 000000000000..900d930d48a8
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/strncmp_test.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <stdbool.h>
+#include <linux/types.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#define STRNCMP_STR_SZ 8
+
+const char target[STRNCMP_STR_SZ] = "EEEEEEE";
+char str[STRNCMP_STR_SZ];
+int cmp_ret = 0;
+int target_pid = 0;
+
+const char no_str_target[STRNCMP_STR_SZ] = "12345678";
+char writable_target[STRNCMP_STR_SZ];
+unsigned int no_const_str_size = STRNCMP_STR_SZ;
+
+char _license[] SEC("license") = "GPL";
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int do_strncmp(void *ctx)
+{
+ if ((bpf_get_current_pid_tgid() >> 32) != target_pid)
+ return 0;
+
+ cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, target);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int strncmp_bad_not_const_str_size(void *ctx)
+{
+ /* The value of string size is not const, so will fail */
+ cmp_ret = bpf_strncmp(str, no_const_str_size, target);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int strncmp_bad_writable_target(void *ctx)
+{
+ /* Compared target is not read-only, so will fail */
+ cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, writable_target);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int strncmp_bad_not_null_term_target(void *ctx)
+{
+ /* Compared target is not null-terminated, so will fail */
+ cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, no_str_target);
+ return 0;
+}
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper
2021-12-10 14:16 [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Hou Tao
` (3 preceding siblings ...)
2021-12-10 14:16 ` [PATCH bpf-next v2 4/4] selftests/bpf: add test cases for bpf_strncmp() Hou Tao
@ 2021-12-12 1:50 ` Alexei Starovoitov
4 siblings, 0 replies; 6+ messages in thread
From: Alexei Starovoitov @ 2021-12-12 1:50 UTC (permalink / raw)
To: Hou Tao
Cc: Alexei Starovoitov, Martin KaFai Lau, Yonghong Song,
Daniel Borkmann, Andrii Nakryiko, Network Development, bpf
On Fri, Dec 10, 2021 at 6:01 AM Hou Tao <houtao1@huawei.com> wrote:
>
> Hi,
>
> The motivation for introducing bpf_strncmp() helper comes from
> two aspects:
>
> (1) clang doesn't always replace strncmp() automatically
> In tracing program, sometimes we need to using a home-made
> strncmp() to check whether or not the file name is expected.
>
> (2) the performance of home-made strncmp is not so good
> As shown in the benchmark in patch #4, the performance of
> bpf_strncmp() helper is 18% or 33% better than home-made strncmp()
> under x86-64 or arm64 when the compared string length is 64. When
> the string length grows to 4095, the performance win will be
> 179% or 600% under x86-64 or arm64.
>
> Any comments are welcome.
> Regards,
> Tao
>
> Change Log:
> v2:
> * rebased on bpf-next
> * drop patch "selftests/bpf: factor out common helpers for benchmarks"
> (suggested by Andrii)
> * remove unnecessary inline functions and add comments for programs which
> will be rejected by verifier in patch 4 (suggested by Andrii)
> * rename variables used in will-fail programs to clarify the purposes.
Applied. Thanks
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2021-12-10 14:16 [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 1/4] bpf: add bpf_strncmp helper Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 2/4] selftests/bpf: fix checkpatch error on empty function parameter Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 3/4] selftests/bpf: add benchmark for bpf_strncmp() helper Hou Tao
2021-12-10 14:16 ` [PATCH bpf-next v2 4/4] selftests/bpf: add test cases for bpf_strncmp() Hou Tao
2021-12-12 1:50 ` [PATCH bpf-next v2 0/4] introduce bpf_strncmp() helper Alexei Starovoitov
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