Some KUnit functions use variable arguments to implement a printf-like
format string. Use the __printf() attribute to let the compiler warn if
invalid format strings are passed in.
If the kernel is build with W=1, it complained about the lack of these
specifiers, e.g.:
../lib/kunit/test.c:72:2: warning: function ‘kunit_log_append’ might be a candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
Signed-off-by: David Gow <[email protected]>
---
include/kunit/test.h | 2 +-
lib/kunit/string-stream.h | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/kunit/test.h b/include/kunit/test.h
index 49601c4b98b8..af2e386b867c 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -610,7 +610,7 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
void kunit_cleanup(struct kunit *test);
-void kunit_log_append(char *log, const char *fmt, ...);
+void __printf(2, 3) kunit_log_append(char *log, const char *fmt, ...);
/*
* printk and log to per-test or per-suite log buffer. Logging only done
diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
index fe98a00b75a9..5e94b623454f 100644
--- a/lib/kunit/string-stream.h
+++ b/lib/kunit/string-stream.h
@@ -35,9 +35,9 @@ struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp);
int __printf(2, 3) string_stream_add(struct string_stream *stream,
const char *fmt, ...);
-int string_stream_vadd(struct string_stream *stream,
- const char *fmt,
- va_list args);
+int __printf(2, 0) string_stream_vadd(struct string_stream *stream,
+ const char *fmt,
+ va_list args);
char *string_stream_get_string(struct string_stream *stream);
--
2.31.1.751.gd2f1c929bd-goog
On Fri, May 14, 2021 at 4:25 AM Daniel Latypov <[email protected]> wrote:
>
> On Thu, May 13, 2021 at 1:03 PM 'David Gow' via KUnit Development
> <[email protected]> wrote:
> >
> > Some KUnit functions use variable arguments to implement a printf-like
> > format string. Use the __printf() attribute to let the compiler warn if
> > invalid format strings are passed in.
> >
> > If the kernel is build with W=1, it complained about the lack of these
> > specifiers, e.g.:
> > ../lib/kunit/test.c:72:2: warning: function ‘kunit_log_append’ might be a candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
> >
> > Signed-off-by: David Gow <[email protected]>
>
> Reviewed-by: Daniel Latypov <[email protected]>
>
> As noted below, these additions don't really do anything.
> Unfortunately, they just make compiler warnings noisier in the case of
> kunit_log_append().
>
> But if this silences a W=1 warning, then we should probably add them in.
> I guess it also serves as documentation that we're using the same
> standard format specifiers and not something custom, which is nice.
>
Yeah: I did this to get rid of the W=1 warnings. I don't know if
there's a way of doing this which would be less verbose: I do think
that the format checking is worthwhile in general, even if we're
hitting a few nasty cases where things are nested in macros.
> > ---
> > include/kunit/test.h | 2 +-
> > lib/kunit/string-stream.h | 6 +++---
> > 2 files changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > index 49601c4b98b8..af2e386b867c 100644
> > --- a/include/kunit/test.h
> > +++ b/include/kunit/test.h
> > @@ -610,7 +610,7 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
> >
> > void kunit_cleanup(struct kunit *test);
> >
> > -void kunit_log_append(char *log, const char *fmt, ...);
> > +void __printf(2, 3) kunit_log_append(char *log, const char *fmt, ...);
>
> Before this patch:
> ../lib/kunit/kunit-example-test.c: In function ‘example_simple_test’:
> ../include/linux/kern_levels.h:5:18: warning: format ‘%s’ expects
> argument of type ‘char *’, but argument 3 has type ‘int’ [-Wformat=]
> 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */
> | ^~~~~~
> ../include/kunit/test.h:622:10: note: in definition of macro ‘kunit_log’
> 622 | printk(lvl fmt, ##__VA_ARGS__); \
> | ^~~
> ../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
> 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> | ^~~~~~~~~~~~
> ../include/linux/kern_levels.h:14:19: note: in expansion of macro ‘KERN_SOH’
> 14 | #define KERN_INFO KERN_SOH "6" /* informational */
> | ^~~~~~~~
> ../include/kunit/test.h:641:15: note: in expansion of macro ‘KERN_INFO’
> 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> | ^~~~~~~~~
> ../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
> 23 | kunit_info(test, "invalid: %s", 42);
>
> After this patch, it gets noisier:
> In file included from ../lib/kunit/kunit-example-test.c:9:
> ../lib/kunit/kunit-example-test.c: In function ‘example_simple_test’:
> ../include/linux/kern_levels.h:5:18: warning: format ‘%s’ expects
> argument of type ‘char *’, but argument 3 has type ‘int’ [-Wformat=]
> 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */
> | ^~~~~~
> ../include/kunit/test.h:622:10: note: in definition of macro ‘kunit_log’
> 622 | printk(lvl fmt, ##__VA_ARGS__); \
> | ^~~
> ../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
> 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> | ^~~~~~~~~~~~
> ../include/linux/kern_levels.h:14:19: note: in expansion of macro ‘KERN_SOH’
> 14 | #define KERN_INFO KERN_SOH "6" /* informational */
> | ^~~~~~~~
> ../include/kunit/test.h:641:15: note: in expansion of macro ‘KERN_INFO’
> 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> | ^~~~~~~~~
> ../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
> 23 | kunit_info(test, "invalid: %s", 42);
> | ^~~~~~~~~~
> ../include/kunit/test.h:105:31: warning: format ‘%s’ expects argument
> of type ‘char *’, but argument 4 has type ‘int’ [-Wformat=]
> 105 | #define KUNIT_SUBTEST_INDENT " "
> | ^~~~~~
> ../include/kunit/test.h:623:42: note: in definition of macro ‘kunit_log’
> 623 | kunit_log_append((test_or_suite)->log, fmt "\n", \
> | ^~~
> ../include/kunit/test.h:628:23: note: in expansion of macro
> ‘KUNIT_SUBTEST_INDENT’
> 628 | kunit_log(lvl, test, KUNIT_SUBTEST_INDENT "# %s: " fmt, \
> | ^~~~~~~~~~~~~~~~~~~~
> ../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
> 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> | ^~~~~~~~~~~~
> ../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
> 23 | kunit_info(test, "invalid: %s", 42);
> | ^~~~~~~~~~
>
>
Yeah: that is pretty ugly. TBH, it was pretty ugly beforehand, and
this does make it worse. I guess that's the price we pay for having so
many nested macros, as well.
Personally, I suspect this is still worth it to get rid of the
compiler warnings, but only just.
> >
> > /*
> > * printk and log to per-test or per-suite log buffer. Logging only done
> > diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
> > index fe98a00b75a9..5e94b623454f 100644
> > --- a/lib/kunit/string-stream.h
> > +++ b/lib/kunit/string-stream.h
> > @@ -35,9 +35,9 @@ struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp);
> > int __printf(2, 3) string_stream_add(struct string_stream *stream,
> > const char *fmt, ...);
> >
> > -int string_stream_vadd(struct string_stream *stream,
> > - const char *fmt,
> > - va_list args);
> > +int __printf(2, 0) string_stream_vadd(struct string_stream *stream,
> > + const char *fmt,
> > + va_list args);
>
> This is never called with a literal `fmt` string.
> It's currently only ever called through the _add variant, which does
> have __printf(2,3).
>
> So this can't catch any mistakes currently.
> And I think it's hard to imagine we'd ever pass in a literal format
> string w/ a va_list.
>
Yeah: I was tempted to leave this one out, but it was triggering
warnings with the "you should use __printf()" heuristic. In fact, it
had two warnings.
The __printf() specifier documentation does specifically call out
cases where a va_list is passed in as a case to use '0' for the
positional argument, but only the format string is checked for
validity: there's no typechecking.
> >
> > char *string_stream_get_string(struct string_stream *stream);
> >
> > --
> > 2.31.1.751.gd2f1c929bd-goog
> >
> > --
> > You received this message because you are subscribed to the Google Groups "KUnit Development" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> > To view this discussion on the web visit https://groups.google.com/d/msgid/kunit-dev/20210513200350.854429-1-davidgow%40google.com.
On Thu, May 13, 2021 at 1:48 PM David Gow <[email protected]> wrote:
>
> On Fri, May 14, 2021 at 4:25 AM Daniel Latypov <[email protected]> wrote:
> >
> > On Thu, May 13, 2021 at 1:03 PM 'David Gow' via KUnit Development
> > <[email protected]> wrote:
> > >
> > > Some KUnit functions use variable arguments to implement a printf-like
> > > format string. Use the __printf() attribute to let the compiler warn if
> > > invalid format strings are passed in.
> > >
> > > If the kernel is build with W=1, it complained about the lack of these
> > > specifiers, e.g.:
> > > ../lib/kunit/test.c:72:2: warning: function ‘kunit_log_append’ might be a candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
> > >
> > > Signed-off-by: David Gow <[email protected]>
> >
> > Reviewed-by: Daniel Latypov <[email protected]>
> >
> > As noted below, these additions don't really do anything.
> > Unfortunately, they just make compiler warnings noisier in the case of
> > kunit_log_append().
> >
> > But if this silences a W=1 warning, then we should probably add them in.
> > I guess it also serves as documentation that we're using the same
> > standard format specifiers and not something custom, which is nice.
> >
>
> Yeah: I did this to get rid of the W=1 warnings. I don't know if
> there's a way of doing this which would be less verbose: I do think
> that the format checking is worthwhile in general, even if we're
> hitting a few nasty cases where things are nested in macros.
Yeah. In case it wasn't clear, I think both annotations are clearly
worth having if they silence W=1 warnings.
We're more likely to produce more noise w/ those warnings than the
extra noise of someone making a typo or forgetting in a kunit_info()
somewhere while writing a test.
It's just a bit sad that doing what the compiler suggests doesn't
really make life better :(
>
>
> > > ---
> > > include/kunit/test.h | 2 +-
> > > lib/kunit/string-stream.h | 6 +++---
> > > 2 files changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > > index 49601c4b98b8..af2e386b867c 100644
> > > --- a/include/kunit/test.h
> > > +++ b/include/kunit/test.h
> > > @@ -610,7 +610,7 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
> > >
> > > void kunit_cleanup(struct kunit *test);
> > >
> > > -void kunit_log_append(char *log, const char *fmt, ...);
> > > +void __printf(2, 3) kunit_log_append(char *log, const char *fmt, ...);
> >
> > Before this patch:
> > ../lib/kunit/kunit-example-test.c: In function ‘example_simple_test’:
> > ../include/linux/kern_levels.h:5:18: warning: format ‘%s’ expects
> > argument of type ‘char *’, but argument 3 has type ‘int’ [-Wformat=]
> > 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */
> > | ^~~~~~
> > ../include/kunit/test.h:622:10: note: in definition of macro ‘kunit_log’
> > 622 | printk(lvl fmt, ##__VA_ARGS__); \
> > | ^~~
> > ../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
> > 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~~~~
> > ../include/linux/kern_levels.h:14:19: note: in expansion of macro ‘KERN_SOH’
> > 14 | #define KERN_INFO KERN_SOH "6" /* informational */
> > | ^~~~~~~~
> > ../include/kunit/test.h:641:15: note: in expansion of macro ‘KERN_INFO’
> > 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~
> > ../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
> > 23 | kunit_info(test, "invalid: %s", 42);
> >
> > After this patch, it gets noisier:
> > In file included from ../lib/kunit/kunit-example-test.c:9:
> > ../lib/kunit/kunit-example-test.c: In function ‘example_simple_test’:
> > ../include/linux/kern_levels.h:5:18: warning: format ‘%s’ expects
> > argument of type ‘char *’, but argument 3 has type ‘int’ [-Wformat=]
> > 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */
> > | ^~~~~~
> > ../include/kunit/test.h:622:10: note: in definition of macro ‘kunit_log’
> > 622 | printk(lvl fmt, ##__VA_ARGS__); \
> > | ^~~
> > ../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
> > 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~~~~
> > ../include/linux/kern_levels.h:14:19: note: in expansion of macro ‘KERN_SOH’
> > 14 | #define KERN_INFO KERN_SOH "6" /* informational */
> > | ^~~~~~~~
> > ../include/kunit/test.h:641:15: note: in expansion of macro ‘KERN_INFO’
> > 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~
> > ../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
> > 23 | kunit_info(test, "invalid: %s", 42);
> > | ^~~~~~~~~~
> > ../include/kunit/test.h:105:31: warning: format ‘%s’ expects argument
> > of type ‘char *’, but argument 4 has type ‘int’ [-Wformat=]
> > 105 | #define KUNIT_SUBTEST_INDENT " "
> > | ^~~~~~
> > ../include/kunit/test.h:623:42: note: in definition of macro ‘kunit_log’
> > 623 | kunit_log_append((test_or_suite)->log, fmt "\n", \
> > | ^~~
> > ../include/kunit/test.h:628:23: note: in expansion of macro
> > ‘KUNIT_SUBTEST_INDENT’
> > 628 | kunit_log(lvl, test, KUNIT_SUBTEST_INDENT "# %s: " fmt, \
> > | ^~~~~~~~~~~~~~~~~~~~
> > ../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
> > 641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~~~~
> > ../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
> > 23 | kunit_info(test, "invalid: %s", 42);
> > | ^~~~~~~~~~
> >
> >
>
> Yeah: that is pretty ugly. TBH, it was pretty ugly beforehand, and
> this does make it worse. I guess that's the price we pay for having so
> many nested macros, as well.
> Personally, I suspect this is still worth it to get rid of the
> compiler warnings, but only just.
>
> > >
> > > /*
> > > * printk and log to per-test or per-suite log buffer. Logging only done
> > > diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
> > > index fe98a00b75a9..5e94b623454f 100644
> > > --- a/lib/kunit/string-stream.h
> > > +++ b/lib/kunit/string-stream.h
> > > @@ -35,9 +35,9 @@ struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp);
> > > int __printf(2, 3) string_stream_add(struct string_stream *stream,
> > > const char *fmt, ...);
> > >
> > > -int string_stream_vadd(struct string_stream *stream,
> > > - const char *fmt,
> > > - va_list args);
> > > +int __printf(2, 0) string_stream_vadd(struct string_stream *stream,
> > > + const char *fmt,
> > > + va_list args);
> >
> > This is never called with a literal `fmt` string.
> > It's currently only ever called through the _add variant, which does
> > have __printf(2,3).
> >
> > So this can't catch any mistakes currently.
> > And I think it's hard to imagine we'd ever pass in a literal format
> > string w/ a va_list.
> >
>
> Yeah: I was tempted to leave this one out, but it was triggering
> warnings with the "you should use __printf()" heuristic. In fact, it
> had two warnings.
> The __printf() specifier documentation does specifically call out
> cases where a va_list is passed in as a case to use '0' for the
> positional argument, but only the format string is checked for
> validity: there's no typechecking.
>
> > >
> > > char *string_stream_get_string(struct string_stream *stream);
> > >
> > > --
> > > 2.31.1.751.gd2f1c929bd-goog
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "KUnit Development" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/kunit-dev/20210513200350.854429-1-davidgow%40google.com.
On Thu, May 13, 2021 at 1:03 PM 'David Gow' via KUnit Development
<[email protected]> wrote:
>
> Some KUnit functions use variable arguments to implement a printf-like
> format string. Use the __printf() attribute to let the compiler warn if
> invalid format strings are passed in.
>
> If the kernel is build with W=1, it complained about the lack of these
> specifiers, e.g.:
> ../lib/kunit/test.c:72:2: warning: function ‘kunit_log_append’ might be a candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
>
> Signed-off-by: David Gow <[email protected]>
Reviewed-by: Daniel Latypov <[email protected]>
As noted below, these additions don't really do anything.
Unfortunately, they just make compiler warnings noisier in the case of
kunit_log_append().
But if this silences a W=1 warning, then we should probably add them in.
I guess it also serves as documentation that we're using the same
standard format specifiers and not something custom, which is nice.
> ---
> include/kunit/test.h | 2 +-
> lib/kunit/string-stream.h | 6 +++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index 49601c4b98b8..af2e386b867c 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
> @@ -610,7 +610,7 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
>
> void kunit_cleanup(struct kunit *test);
>
> -void kunit_log_append(char *log, const char *fmt, ...);
> +void __printf(2, 3) kunit_log_append(char *log, const char *fmt, ...);
Before this patch:
../lib/kunit/kunit-example-test.c: In function ‘example_simple_test’:
../include/linux/kern_levels.h:5:18: warning: format ‘%s’ expects
argument of type ‘char *’, but argument 3 has type ‘int’ [-Wformat=]
5 | #define KERN_SOH "\001" /* ASCII Start Of Header */
| ^~~~~~
../include/kunit/test.h:622:10: note: in definition of macro ‘kunit_log’
622 | printk(lvl fmt, ##__VA_ARGS__); \
| ^~~
../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
| ^~~~~~~~~~~~
../include/linux/kern_levels.h:14:19: note: in expansion of macro ‘KERN_SOH’
14 | #define KERN_INFO KERN_SOH "6" /* informational */
| ^~~~~~~~
../include/kunit/test.h:641:15: note: in expansion of macro ‘KERN_INFO’
641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
| ^~~~~~~~~
../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
23 | kunit_info(test, "invalid: %s", 42);
After this patch, it gets noisier:
In file included from ../lib/kunit/kunit-example-test.c:9:
../lib/kunit/kunit-example-test.c: In function ‘example_simple_test’:
../include/linux/kern_levels.h:5:18: warning: format ‘%s’ expects
argument of type ‘char *’, but argument 3 has type ‘int’ [-Wformat=]
5 | #define KERN_SOH "\001" /* ASCII Start Of Header */
| ^~~~~~
../include/kunit/test.h:622:10: note: in definition of macro ‘kunit_log’
622 | printk(lvl fmt, ##__VA_ARGS__); \
| ^~~
../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
| ^~~~~~~~~~~~
../include/linux/kern_levels.h:14:19: note: in expansion of macro ‘KERN_SOH’
14 | #define KERN_INFO KERN_SOH "6" /* informational */
| ^~~~~~~~
../include/kunit/test.h:641:15: note: in expansion of macro ‘KERN_INFO’
641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
| ^~~~~~~~~
../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
23 | kunit_info(test, "invalid: %s", 42);
| ^~~~~~~~~~
../include/kunit/test.h:105:31: warning: format ‘%s’ expects argument
of type ‘char *’, but argument 4 has type ‘int’ [-Wformat=]
105 | #define KUNIT_SUBTEST_INDENT " "
| ^~~~~~
../include/kunit/test.h:623:42: note: in definition of macro ‘kunit_log’
623 | kunit_log_append((test_or_suite)->log, fmt "\n", \
| ^~~
../include/kunit/test.h:628:23: note: in expansion of macro
‘KUNIT_SUBTEST_INDENT’
628 | kunit_log(lvl, test, KUNIT_SUBTEST_INDENT "# %s: " fmt, \
| ^~~~~~~~~~~~~~~~~~~~
../include/kunit/test.h:641:2: note: in expansion of macro ‘kunit_printk’
641 | kunit_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
| ^~~~~~~~~~~~
../lib/kunit/kunit-example-test.c:23:2: note: in expansion of macro ‘kunit_info’
23 | kunit_info(test, "invalid: %s", 42);
| ^~~~~~~~~~
>
> /*
> * printk and log to per-test or per-suite log buffer. Logging only done
> diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
> index fe98a00b75a9..5e94b623454f 100644
> --- a/lib/kunit/string-stream.h
> +++ b/lib/kunit/string-stream.h
> @@ -35,9 +35,9 @@ struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp);
> int __printf(2, 3) string_stream_add(struct string_stream *stream,
> const char *fmt, ...);
>
> -int string_stream_vadd(struct string_stream *stream,
> - const char *fmt,
> - va_list args);
> +int __printf(2, 0) string_stream_vadd(struct string_stream *stream,
> + const char *fmt,
> + va_list args);
This is never called with a literal `fmt` string.
It's currently only ever called through the _add variant, which does
have __printf(2,3).
So this can't catch any mistakes currently.
And I think it's hard to imagine we'd ever pass in a literal format
string w/ a va_list.
>
> char *string_stream_get_string(struct string_stream *stream);
>
> --
> 2.31.1.751.gd2f1c929bd-goog
>
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On Thu, May 13, 2021 at 1:03 PM David Gow <[email protected]> wrote:
>
> Some KUnit functions use variable arguments to implement a printf-like
> format string. Use the __printf() attribute to let the compiler warn if
> invalid format strings are passed in.
>
> If the kernel is build with W=1, it complained about the lack of these
> specifiers, e.g.:
> ../lib/kunit/test.c:72:2: warning: function ‘kunit_log_append’ might be a candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
>
> Signed-off-by: David Gow <[email protected]>
Acked-by: Brendan Higgins <[email protected]>