diff mbox series

[RFC,bpf-next,v1,5/8] selftests/bpf: no need to track next_match_pos in struct test_loader

Message ID 20240629094733.3863850-6-eddyz87@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series no_caller_saved_registers attribute for helper calls | expand

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Commit Message

Eduard Zingerman June 29, 2024, 9:47 a.m. UTC 
The call stack for validate_case() function looks as follows:
- test_loader__run_subtests()
  - process_subtest()
    - run_subtest()
      - prepare_case(), which does 'tester->next_match_pos = 0';
      - validate_case(), which increments tester->next_match_pos.

Hence, each subtest is run with next_match_pos freshly set to zero.
Meaning that there is no need to persist this variable in the
struct test_loader, use local variable instead.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 tools/testing/selftests/bpf/test_loader.c | 17 ++++++++---------
 tools/testing/selftests/bpf/test_progs.h  |  1 -
 2 files changed, 8 insertions(+), 10 deletions(-)

Comments

Andrii Nakryiko July 2, 2024, 12:41 a.m. UTC | #1 
On Sat, Jun 29, 2024 at 2:48 AM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> The call stack for validate_case() function looks as follows:
> - test_loader__run_subtests()
>   - process_subtest()
>     - run_subtest()
>       - prepare_case(), which does 'tester->next_match_pos = 0';
>       - validate_case(), which increments tester->next_match_pos.
>
> Hence, each subtest is run with next_match_pos freshly set to zero.
> Meaning that there is no need to persist this variable in the
> struct test_loader, use local variable instead.
>
> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
> ---
>  tools/testing/selftests/bpf/test_loader.c | 17 ++++++++---------
>  tools/testing/selftests/bpf/test_progs.h  |  1 -
>  2 files changed, 8 insertions(+), 10 deletions(-)
>

Nice cleanup:

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c
> index f14e10b0de96..ac9d3e81abdb 100644
> --- a/tools/testing/selftests/bpf/test_loader.c
> +++ b/tools/testing/selftests/bpf/test_loader.c
> @@ -434,7 +434,6 @@ static void prepare_case(struct test_loader *tester,
>         bpf_program__set_flags(prog, prog_flags | spec->prog_flags);
>
>         tester->log_buf[0] = '\0';
> -       tester->next_match_pos = 0;
>  }
>
>  static void emit_verifier_log(const char *log_buf, bool force)
> @@ -450,23 +449,23 @@ static void validate_case(struct test_loader *tester,
>                           struct bpf_program *prog,
>                           int load_err)
>  {
> -       int i, j, err;
> -       char *match;
>         regmatch_t reg_match[1];
> +       const char *match;
> +       const char *log = tester->log_buf;
> +       int i, j, err;
>
>         for (i = 0; i < subspec->expect_msg_cnt; i++) {
>                 struct expect_msg *msg = &subspec->expect_msgs[i];
>
>                 if (msg->substr) {
> -                       match = strstr(tester->log_buf + tester->next_match_pos, msg->substr);
> +                       match = strstr(log, msg->substr);
>                         if (match)
> -                               tester->next_match_pos = match - tester->log_buf + strlen(msg->substr);
> +                               log += strlen(msg->substr);
>                 } else {
> -                       err = regexec(&msg->regex,
> -                                     tester->log_buf + tester->next_match_pos, 1, reg_match, 0);
> +                       err = regexec(&msg->regex, log, 1, reg_match, 0);
>                         if (err == 0) {
> -                               match = tester->log_buf + tester->next_match_pos + reg_match[0].rm_so;
> -                               tester->next_match_pos += reg_match[0].rm_eo;
> +                               match = log + reg_match[0].rm_so;
> +                               log += reg_match[0].rm_eo;

invert and simplify:

log += reg_match[0].rm_eo;
match = log;

?

>                         } else {
>                                 match = NULL;
>                         }

how about we move this to the beginning of iteration (before `if
(msg->substr)`) and so we'll assume the match is NULL on regexec
failing?


> diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
> index 0ba5a20b19ba..8e997de596db 100644
> --- a/tools/testing/selftests/bpf/test_progs.h
> +++ b/tools/testing/selftests/bpf/test_progs.h
> @@ -438,7 +438,6 @@ typedef int (*pre_execution_cb)(struct bpf_object *obj);
>  struct test_loader {
>         char *log_buf;
>         size_t log_buf_sz;
> -       size_t next_match_pos;
>         pre_execution_cb pre_execution_cb;
>
>         struct bpf_object *obj;
> --
> 2.45.2
>
Eduard Zingerman July 2, 2024, 9:05 p.m. UTC | #2 
On Mon, 2024-07-01 at 17:41 -0700, Andrii Nakryiko wrote:

[...]

> >  static void emit_verifier_log(const char *log_buf, bool force)
> > @@ -450,23 +449,23 @@ static void validate_case(struct test_loader *tester,
> >                           struct bpf_program *prog,
> >                           int load_err)
> >  {
> > -       int i, j, err;
> > -       char *match;
> >         regmatch_t reg_match[1];
> > +       const char *match;
> > +       const char *log = tester->log_buf;
> > +       int i, j, err;
> > 
> >         for (i = 0; i < subspec->expect_msg_cnt; i++) {
> >                 struct expect_msg *msg = &subspec->expect_msgs[i];
> > 
> >                 if (msg->substr) {
> > -                       match = strstr(tester->log_buf + tester->next_match_pos, msg->substr);
> > +                       match = strstr(log, msg->substr);
> >                         if (match)
> > -                               tester->next_match_pos = match - tester->log_buf + strlen(msg->substr);
> > +                               log += strlen(msg->substr);
> >                 } else {
> > -                       err = regexec(&msg->regex,
> > -                                     tester->log_buf + tester->next_match_pos, 1, reg_match, 0);
> > +                       err = regexec(&msg->regex, log, 1, reg_match, 0);
> >                         if (err == 0) {
> > -                               match = tester->log_buf + tester->next_match_pos + reg_match[0].rm_so;
> > -                               tester->next_match_pos += reg_match[0].rm_eo;
> > +                               match = log + reg_match[0].rm_so;
> > +                               log += reg_match[0].rm_eo;
> 
> invert and simplify:
> 
> log += reg_match[0].rm_eo;
> match = log;
> 
> ?

The 'match' is at 'log + rm_so' (start offset).
The 'log'   is at 'log + rm_eo' (end offset).

The brilliance of standard library naming.

> 
> >                         } else {
> >                                 match = NULL;
> >                         }
> 
> how about we move this to the beginning of iteration (before `if
> (msg->substr)`) and so we'll assume the match is NULL on regexec
> failing?

Ok, but this would require explicit match re-initialization to NULL at
each iteration.

[...]
Andrii Nakryiko July 2, 2024, 9:18 p.m. UTC | #3 
On Tue, Jul 2, 2024 at 2:05 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> On Mon, 2024-07-01 at 17:41 -0700, Andrii Nakryiko wrote:
>
> [...]
>
> > >  static void emit_verifier_log(const char *log_buf, bool force)
> > > @@ -450,23 +449,23 @@ static void validate_case(struct test_loader *tester,
> > >                           struct bpf_program *prog,
> > >                           int load_err)
> > >  {
> > > -       int i, j, err;
> > > -       char *match;
> > >         regmatch_t reg_match[1];
> > > +       const char *match;
> > > +       const char *log = tester->log_buf;
> > > +       int i, j, err;
> > >
> > >         for (i = 0; i < subspec->expect_msg_cnt; i++) {
> > >                 struct expect_msg *msg = &subspec->expect_msgs[i];
> > >
> > >                 if (msg->substr) {
> > > -                       match = strstr(tester->log_buf + tester->next_match_pos, msg->substr);
> > > +                       match = strstr(log, msg->substr);
> > >                         if (match)
> > > -                               tester->next_match_pos = match - tester->log_buf + strlen(msg->substr);
> > > +                               log += strlen(msg->substr);
> > >                 } else {
> > > -                       err = regexec(&msg->regex,
> > > -                                     tester->log_buf + tester->next_match_pos, 1, reg_match, 0);
> > > +                       err = regexec(&msg->regex, log, 1, reg_match, 0);
> > >                         if (err == 0) {
> > > -                               match = tester->log_buf + tester->next_match_pos + reg_match[0].rm_so;
> > > -                               tester->next_match_pos += reg_match[0].rm_eo;
> > > +                               match = log + reg_match[0].rm_so;
> > > +                               log += reg_match[0].rm_eo;
> >
> > invert and simplify:
> >
> > log += reg_match[0].rm_eo;
> > match = log;
> >
> > ?
>
> The 'match' is at 'log + rm_so' (start offset).
> The 'log'   is at 'log + rm_eo' (end offset).
>

oh... yeah... never mind... */me retreats*

> The brilliance of standard library naming.
>
> >
> > >                         } else {
> > >                                 match = NULL;
> > >                         }
> >
> > how about we move this to the beginning of iteration (before `if
> > (msg->substr)`) and so we'll assume the match is NULL on regexec
> > failing?
>
> Ok, but this would require explicit match re-initialization to NULL at
> each iteration.

yes, which also makes it clear that we don't carry over match in
between iterations (we can move `const char *match` inside the for
loop to make it even clearer)

>
> [...]
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c
index f14e10b0de96..ac9d3e81abdb 100644
--- a/tools/testing/selftests/bpf/test_loader.c
+++ b/tools/testing/selftests/bpf/test_loader.c
@@ -434,7 +434,6 @@  static void prepare_case(struct test_loader *tester,
 	bpf_program__set_flags(prog, prog_flags | spec->prog_flags);
 
 	tester->log_buf[0] = '\0';
-	tester->next_match_pos = 0;
 }
 
 static void emit_verifier_log(const char *log_buf, bool force)
@@ -450,23 +449,23 @@  static void validate_case(struct test_loader *tester,
 			  struct bpf_program *prog,
 			  int load_err)
 {
-	int i, j, err;
-	char *match;
 	regmatch_t reg_match[1];
+	const char *match;
+	const char *log = tester->log_buf;
+	int i, j, err;
 
 	for (i = 0; i < subspec->expect_msg_cnt; i++) {
 		struct expect_msg *msg = &subspec->expect_msgs[i];
 
 		if (msg->substr) {
-			match = strstr(tester->log_buf + tester->next_match_pos, msg->substr);
+			match = strstr(log, msg->substr);
 			if (match)
-				tester->next_match_pos = match - tester->log_buf + strlen(msg->substr);
+				log += strlen(msg->substr);
 		} else {
-			err = regexec(&msg->regex,
-				      tester->log_buf + tester->next_match_pos, 1, reg_match, 0);
+			err = regexec(&msg->regex, log, 1, reg_match, 0);
 			if (err == 0) {
-				match = tester->log_buf + tester->next_match_pos + reg_match[0].rm_so;
-				tester->next_match_pos += reg_match[0].rm_eo;
+				match = log + reg_match[0].rm_so;
+				log += reg_match[0].rm_eo;
 			} else {
 				match = NULL;
 			}
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index 0ba5a20b19ba..8e997de596db 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -438,7 +438,6 @@  typedef int (*pre_execution_cb)(struct bpf_object *obj);
 struct test_loader {
 	char *log_buf;
 	size_t log_buf_sz;
-	size_t next_match_pos;
 	pre_execution_cb pre_execution_cb;
 
 	struct bpf_object *obj;