Re: [PATCH v2] kunit: fix failure to build without printk

Joe Perches
2019-08-30T20:47:02Z

On Fri, 2019-08-30 at 11:38 -0700, Brendan Higgins wrote:
> On Thu, Aug 29, 2019 at 09:44:58PM -0700, Joe Perches wrote:
> > On Thu, 2019-08-29 at 11:01 -0600, shuah wrote:
> > > On 8/28/19 3:49 AM, Sergey Senozhatsky wrote:
> > > > On (08/28/19 02:31), Brendan Higgins wrote:
> > > > [..]
> > > > > Previously KUnit assumed that printk would always be present, which is
> > > > > not a valid assumption to make. Fix that by removing call to
> > > > > vprintk_emit, and calling printk directly.
> > > > >
> > > > > Reported-by: Randy Dunlap <rdunlap@infradead.org>
> > > > > Link: https://lore.kernel.org/linux-kselftest/0352fae9-564f-4a97-715a-fabe016259df@kernel.org/T/#t
> > > > > Cc: Stephen Rothwell <sfr@canb.auug.org.au>
> > > > > Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
> > > > > Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
> > > >
> > > > [..]
> > > >
> > > > > -static void kunit_vprintk(const struct kunit *test,
> > > > > - const char *level,
> > > > > - struct va_format *vaf)
> > > > > -{
> > > > > - kunit_printk_emit(level[1] - '0', "\t# %s: %pV", test->name, vaf);
> > > > > -}
> > > >
> > > > This patch looks good to me. I like the removal of recursive
> > > > vsprintf() (%pV).
> > > >
> > > > -ss
> > > >
> > >
> > > Hi Sergey,
> > >
> > > What are the guidelines for using printk(). I recall some discussion
> > > about not using printk(). I am seeing the following from checkpatch
> > > script:
> > >
> > >
> > > WARNING: Prefer [subsystem eg: netdev]_level([subsystem]dev, ... then
> > > dev_level(dev, ... then pr_level(... to printk(KERN_LEVEL ...
> > > #105: FILE: include/kunit/test.h:343:
> > > + printk(KERN_LEVEL "\t# %s: " fmt, (test)->name, ##__VA_ARGS__)
> > >
> > >
> > > Is there supposed to be pr_level() - I can find dev_level()
> > >
> > > cc'ing Joe Perches for his feedback on this message recommending
> > > pr_level() which isn't in 5.3.
> >
> > I don't care for pr_level or KERN_LEVEL in a printk.
>
> I don't think I follow, how does your version fix this?
>
> > I think this is somewhat overly complicated.
> >
> > I think I'd write it like:
> > ---
> > include/kunit/test.h | 11 ++++-----
> > kunit/test.c | 69 ++++++++++++++++------------------------------------
> > 2 files changed, 26 insertions(+), 54 deletions(-)
> >
> > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > index 8b7eb03d4971..aa4abf0a22a5 100644
> > --- a/include/kunit/test.h
> > +++ b/include/kunit/test.h
> > @@ -339,9 +339,8 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
> >
> > void kunit_cleanup(struct kunit *test);
> >
> > -void __printf(3, 4) kunit_printk(const char *level,
> > - const struct kunit *test,
> > - const char *fmt, ...);
> > +__printf(2, 3)
> > +void kunit_printk(const struct kunit *test, const char *fmt, ...);
> >
> > /**
> > * kunit_info() - Prints an INFO level message associated with @test.
> > @@ -353,7 +352,7 @@ void __printf(3, 4) kunit_printk(const char *level,
> > * Takes a variable number of format parameters just like printk().
> > */
> > #define kunit_info(test, fmt, ...) \
> > - kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> > + kunit_printk(test, KERN_INFO fmt, ##__VA_ARGS__)
> >
> > /**
> > * kunit_warn() - Prints a WARN level message associated with @test.
> > @@ -364,7 +363,7 @@ void __printf(3, 4) kunit_printk(const char *level,
> > * Prints a warning level message.
> > */
> > #define kunit_warn(test, fmt, ...) \
> > - kunit_printk(KERN_WARNING, test, fmt, ##__VA_ARGS__)
> > + kunit_printk(test, KERN_WARNING fmt, ##__VA_ARGS__)
> >
> > /**
> > * kunit_err() - Prints an ERROR level message associated with @test.
> > @@ -375,7 +374,7 @@ void __printf(3, 4) kunit_printk(const char *level,
> > * Prints an error level message.
> > */
> > #define kunit_err(test, fmt, ...) \
> > - kunit_printk(KERN_ERR, test, fmt, ##__VA_ARGS__)
> > + kunit_printk(test, KERN_ERR fmt, ##__VA_ARGS__)
> >
> > /**
> > * KUNIT_SUCCEED() - A no-op expectation. Only exists for code clarity.
> > diff --git a/kunit/test.c b/kunit/test.c
> > index b2ca9b94c353..ddb9bffb5a5d 100644
> > --- a/kunit/test.c
> > +++ b/kunit/test.c
> > @@ -16,40 +16,6 @@ static void kunit_set_failure(struct kunit *test)
> > WRITE_ONCE(test->success, false);
> > }
> >
> > -static int kunit_vprintk_emit(int level, const char *fmt, va_list args)
> > -{
> > - return vprintk_emit(0, level, NULL, 0, fmt, args);
> > -}
> > -
> > -static int kunit_printk_emit(int level, const char *fmt, ...)
> > -{
> > - va_list args;
> > - int ret;
> > -
> > - va_start(args, fmt);
> > - ret = kunit_vprintk_emit(level, fmt, args);
> > - va_end(args);
> > -
> > - return ret;
> > -}
> > -
> > -static void kunit_vprintk(const struct kunit *test,
> > - const char *level,
> > - struct va_format *vaf)
> > -{
> > - kunit_printk_emit(level[1] - '0', "\t# %s: %pV", test->name, vaf);
> > -}
> > -
> > -static void kunit_print_tap_version(void)
> > -{
> > - static bool kunit_has_printed_tap_version;
> > -
> > - if (!kunit_has_printed_tap_version) {
> > - kunit_printk_emit(LOGLEVEL_INFO, "TAP version 14\n");
> > - kunit_has_printed_tap_version = true;
> > - }
> > -}
> > -
> > static size_t kunit_test_cases_len(struct kunit_case *test_cases)
> > {
> > struct kunit_case *test_case;
> > @@ -63,11 +29,9 @@ static size_t kunit_test_cases_len(struct kunit_case *test_cases)
> >
> > static void kunit_print_subtest_start(struct kunit_suite *suite)
> > {
> > - kunit_print_tap_version();
> > - kunit_printk_emit(LOGLEVEL_INFO, "\t# Subtest: %s\n", suite->name);
> > - kunit_printk_emit(LOGLEVEL_INFO,
> > - "\t1..%zd\n",
> > - kunit_test_cases_len(suite->test_cases));
> > + pr_info_once("TAP version 14\n");
> > + pr_info("\t# Subtest: %s\n", suite->name);
> > + pr_info("\t1..%zd\n", kunit_test_cases_len(suite->test_cases));
> > }
> >
> > static void kunit_print_ok_not_ok(bool should_indent,
> > @@ -87,9 +51,8 @@ static void kunit_print_ok_not_ok(bool should_indent,
> > else
> > ok_not_ok = "not ok";
> >
> > - kunit_printk_emit(LOGLEVEL_INFO,
> > - "%s%s %zd - %s\n",
> > - indent, ok_not_ok, test_number, description);
> > + pr_info("%s%s %zd - %s\n",
> > + indent, ok_not_ok, test_number, description);
> > }
> >
> > static bool kunit_suite_has_succeeded(struct kunit_suite *suite)
> > @@ -133,11 +96,11 @@ static void kunit_print_string_stream(struct kunit *test,
> > kunit_err(test,
> > "Could not allocate buffer, dumping stream:\n");
> > list_for_each_entry(fragment, &stream->fragments, node) {
> > - kunit_err(test, fragment->fragment);
> > + kunit_err(test, "%s", fragment->fragment);
> > }
> > kunit_err(test, "\n");
> > } else {
> > - kunit_err(test, buf);
> > + kunit_err(test, "%s", buf);
> > kunit_kfree(test, buf);
> > }
> > }
> > @@ -505,19 +468,29 @@ void kunit_cleanup(struct kunit *test)
> > }
> > }
> >
> > -void kunit_printk(const char *level,
> > - const struct kunit *test,
> > - const char *fmt, ...)
> > +void kunit_printk(const struct kunit *test, const char *fmt, ...)
> > {
> > + char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
> > struct va_format vaf;
> > va_list args;
> > + int kern_level;
> >
> > va_start(args, fmt);
> >
> > + while ((kern_level = printk_get_level(fmt)) != 0) {
> > + size_t size = printk_skip_level(fmt) - fmt;
> > +
> > + if (kern_level >= '0' && kern_level <= '7') {
> > + memcpy(lvl, fmt, size);
> > + lvl[size] = '\0';
> > + }
> > + fmt += size;
> > + }
> > +
> > vaf.fmt = fmt;
> > vaf.va = &args;
> >
> > - kunit_vprintk(test, level, &vaf);
> > + printk("%s\t# %s %pV\n", lvl, test->name, &vaf);
> >
> > va_end(args);
> > }
>
> How is this simpler?
>
> If we are okay with dynamically adding the KERN_<LEVEL> and %pV (and I
> don't think that Sergey is),

Sergey may well be in the minority overall as %pV
is now very frequently
used throughout the kernel.

$ git grep "%pV" | wc -l
241

then wouldn't it be easier to pass in the
> kernel level as a separate parameter and then strip off all printk
> headers like this:

Depends on whether or not you care for overall
object size. Consolidated formats with the
embedded KERN_<LEVEL> like suggested are smaller
overall object size.

This style is also already used in the kernel.

> I don't know. I am clearly not an expert on this topic, but I don't see
> the merit of the while loop you added above or dropping the level param.

The while use is only to avoid misuses with consecutive
KERN_<LEVEL> formats, which had happened in the past.