| Message ID | 20190110042157.8445-1-natechancellor@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | Jeff Kirsher |
| Headers | show |
| Series | iavf: Use printf instead of gnu_printf for iavf_debug_d | expand |
On Wed, Jan 9, 2019 at 8:22 PM Nathan Chancellor <natechancellor@gmail.com> wrote: > > Clang warns: > > In file included from drivers/net/ethernet/intel/iavf/iavf_main.c:4: > In file included from drivers/net/ethernet/intel/iavf/iavf.h:37: > In file included from drivers/net/ethernet/intel/iavf/iavf_type.h:8: > drivers/net/ethernet/intel/iavf/iavf_osdep.h:49:18: warning: 'format' attribute argument not supported: gnu_printf [-Wignored-attributes] > __attribute__ ((format(gnu_printf, 3, 4))); > ^ > 1 warning generated. > > We can convert from gnu_printf to printf without any side effects for > two reasons: > > 1. All iavf_debug instances use standard printf formats, as pointed out > by Miguel Ojeda at the below link, meaning gnu_printf is not strictly > required. > > 2. However, GCC has aliased printf to gnu_printf on Linux since at least > 2010 based on git history. Thanks for this fix! FWIW, using godbolt to see which version something was added in is better than giving a year of the commit. I don't think it matters for this case, as the kernel already makes use of `printf` as you do in this change, but food for thought for next time. > > From gcc/c-family/c-format.c: > > /* Attributes such as "printf" are equivalent to those such as > "gnu_printf" unless this is overridden by a target. */ > static const target_ovr_attr gnu_target_overrides_format_attributes[] = > { > { "gnu_printf", "printf" }, > { "gnu_scanf", "scanf" }, > { "gnu_strftime", "strftime" }, > { "gnu_strfmon", "strfmon" }, > { NULL, NULL } > }; > > The mentioned override only happens on Windows (mingw32). Changing from > gnu_printf to printf is a no-op for GCC and stops Clang from warning. > > Link: https://github.com/ClangBuiltLinux/linux/issues/111 > Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > drivers/net/ethernet/intel/iavf/iavf_osdep.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/iavf/iavf_osdep.h b/drivers/net/ethernet/intel/iavf/iavf_osdep.h > index e6e0b0328706..c90cafb526d0 100644 > --- a/drivers/net/ethernet/intel/iavf/iavf_osdep.h > +++ b/drivers/net/ethernet/intel/iavf/iavf_osdep.h > @@ -46,7 +46,7 @@ struct iavf_virt_mem { > > #define iavf_debug(h, m, s, ...) iavf_debug_d(h, m, s, ##__VA_ARGS__) > extern void iavf_debug_d(void *hw, u32 mask, char *fmt_str, ...) > - __attribute__ ((format(gnu_printf, 3, 4))); > + __printf(3, 4); And you make use of the __attribute__ wrapper from include/linux/compiler_attributes.h, cool. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
On Thu, Jan 10, 2019 at 10:54:46AM -0800, Nick Desaulniers wrote: > On Wed, Jan 9, 2019 at 8:22 PM Nathan Chancellor > <natechancellor@gmail.com> wrote: > > > > Clang warns: > > > > In file included from drivers/net/ethernet/intel/iavf/iavf_main.c:4: > > In file included from drivers/net/ethernet/intel/iavf/iavf.h:37: > > In file included from drivers/net/ethernet/intel/iavf/iavf_type.h:8: > > drivers/net/ethernet/intel/iavf/iavf_osdep.h:49:18: warning: 'format' attribute argument not supported: gnu_printf [-Wignored-attributes] > > __attribute__ ((format(gnu_printf, 3, 4))); > > ^ > > 1 warning generated. > > > > We can convert from gnu_printf to printf without any side effects for > > two reasons: > > > > 1. All iavf_debug instances use standard printf formats, as pointed out > > by Miguel Ojeda at the below link, meaning gnu_printf is not strictly > > required. > > > > 2. However, GCC has aliased printf to gnu_printf on Linux since at least > > 2010 based on git history. > > Thanks for this fix! > FWIW, using godbolt to see which version something was added in is > better than giving a year of the commit. I don't think it matters for > this case, as the kernel already makes use of `printf` as you do in > this change, but food for thought for next time. > Yes that is a good point, I need to be taking advantage of that site more. Thank you for the review! Nathan > > > > From gcc/c-family/c-format.c: > > > > /* Attributes such as "printf" are equivalent to those such as > > "gnu_printf" unless this is overridden by a target. */ > > static const target_ovr_attr gnu_target_overrides_format_attributes[] = > > { > > { "gnu_printf", "printf" }, > > { "gnu_scanf", "scanf" }, > > { "gnu_strftime", "strftime" }, > > { "gnu_strfmon", "strfmon" }, > > { NULL, NULL } > > }; > > > > The mentioned override only happens on Windows (mingw32). Changing from > > gnu_printf to printf is a no-op for GCC and stops Clang from warning. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/111 > > Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> > > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > > --- > > drivers/net/ethernet/intel/iavf/iavf_osdep.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/ethernet/intel/iavf/iavf_osdep.h b/drivers/net/ethernet/intel/iavf/iavf_osdep.h > > index e6e0b0328706..c90cafb526d0 100644 > > --- a/drivers/net/ethernet/intel/iavf/iavf_osdep.h > > +++ b/drivers/net/ethernet/intel/iavf/iavf_osdep.h > > @@ -46,7 +46,7 @@ struct iavf_virt_mem { > > > > #define iavf_debug(h, m, s, ...) iavf_debug_d(h, m, s, ##__VA_ARGS__) > > extern void iavf_debug_d(void *hw, u32 mask, char *fmt_str, ...) > > - __attribute__ ((format(gnu_printf, 3, 4))); > > + __printf(3, 4); > > And you make use of the __attribute__ wrapper from > include/linux/compiler_attributes.h, cool. > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > > -- > Thanks, > ~Nick Desaulniers
Hi Nathan, On Thu, Jan 10, 2019 at 5:22 AM Nathan Chancellor <natechancellor@gmail.com> wrote: > > Clang warns: > > In file included from drivers/net/ethernet/intel/iavf/iavf_main.c:4: > In file included from drivers/net/ethernet/intel/iavf/iavf.h:37: > In file included from drivers/net/ethernet/intel/iavf/iavf_type.h:8: > drivers/net/ethernet/intel/iavf/iavf_osdep.h:49:18: warning: 'format' attribute argument not supported: gnu_printf [-Wignored-attributes] > __attribute__ ((format(gnu_printf, 3, 4))); > ^ > 1 warning generated. > > We can convert from gnu_printf to printf without any side effects for > two reasons: > > 1. All iavf_debug instances use standard printf formats, as pointed out > by Miguel Ojeda at the below link, meaning gnu_printf is not strictly > required. > > 2. However, GCC has aliased printf to gnu_printf on Linux since at least > 2010 based on git history. > > From gcc/c-family/c-format.c: > > /* Attributes such as "printf" are equivalent to those such as > "gnu_printf" unless this is overridden by a target. */ > static const target_ovr_attr gnu_target_overrides_format_attributes[] = > { > { "gnu_printf", "printf" }, > { "gnu_scanf", "scanf" }, > { "gnu_strftime", "strftime" }, > { "gnu_strfmon", "strfmon" }, > { NULL, NULL } > }; > > The mentioned override only happens on Windows (mingw32). Changing from > gnu_printf to printf is a no-op for GCC and stops Clang from warning. > > Link: https://github.com/ClangBuiltLinux/linux/issues/111 > Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> I forgot, in case you wanted it: Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Thanks for taking care of writing the patch! Cheers, Miguel
> -----Original Message----- > From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On > Behalf Of Nathan Chancellor > Sent: Wednesday, January 9, 2019 8:22 PM > To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com> > Cc: netdev@vger.kernel.org; Nick Desaulniers <ndesaulniers@google.com>; > linux-kernel@vger.kernel.org; Miguel Ojeda > <miguel.ojeda.sandonis@gmail.com>; intel-wired-lan@lists.osuosl.org; > Nathan Chancellor <natechancellor@gmail.com>; David S. Miller > <davem@davemloft.net> > Subject: [Intel-wired-lan] [PATCH] iavf: Use printf instead of gnu_printf for > iavf_debug_d > > Clang warns: > > In file included from drivers/net/ethernet/intel/iavf/iavf_main.c:4: > In file included from drivers/net/ethernet/intel/iavf/iavf.h:37: > In file included from drivers/net/ethernet/intel/iavf/iavf_type.h:8: > drivers/net/ethernet/intel/iavf/iavf_osdep.h:49:18: warning: 'format' > attribute argument not supported: gnu_printf [-Wignored-attributes] > __attribute__ ((format(gnu_printf, 3, 4))); > ^ > 1 warning generated. > > We can convert from gnu_printf to printf without any side effects for two > reasons: > > 1. All iavf_debug instances use standard printf formats, as pointed out > by Miguel Ojeda at the below link, meaning gnu_printf is not strictly > required. > > 2. However, GCC has aliased printf to gnu_printf on Linux since at least > 2010 based on git history. > > From gcc/c-family/c-format.c: > > /* Attributes such as "printf" are equivalent to those such as > "gnu_printf" unless this is overridden by a target. */ > static const target_ovr_attr gnu_target_overrides_format_attributes[] = > { > { "gnu_printf", "printf" }, > { "gnu_scanf", "scanf" }, > { "gnu_strftime", "strftime" }, > { "gnu_strfmon", "strfmon" }, > { NULL, NULL } > }; > > The mentioned override only happens on Windows (mingw32). Changing > from gnu_printf to printf is a no-op for GCC and stops Clang from warning. > > Link: https://github.com/ClangBuiltLinux/linux/issues/111 > Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > drivers/net/ethernet/intel/iavf/iavf_osdep.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
diff --git a/drivers/net/ethernet/intel/iavf/iavf_osdep.h b/drivers/net/ethernet/intel/iavf/iavf_osdep.h index e6e0b0328706..c90cafb526d0 100644 --- a/drivers/net/ethernet/intel/iavf/iavf_osdep.h +++ b/drivers/net/ethernet/intel/iavf/iavf_osdep.h @@ -46,7 +46,7 @@ struct iavf_virt_mem { #define iavf_debug(h, m, s, ...) iavf_debug_d(h, m, s, ##__VA_ARGS__) extern void iavf_debug_d(void *hw, u32 mask, char *fmt_str, ...) - __attribute__ ((format(gnu_printf, 3, 4))); + __printf(3, 4); typedef enum iavf_status_code iavf_status; #endif /* _IAVF_OSDEP_H_ */
Clang warns: In file included from drivers/net/ethernet/intel/iavf/iavf_main.c:4: In file included from drivers/net/ethernet/intel/iavf/iavf.h:37: In file included from drivers/net/ethernet/intel/iavf/iavf_type.h:8: drivers/net/ethernet/intel/iavf/iavf_osdep.h:49:18: warning: 'format' attribute argument not supported: gnu_printf [-Wignored-attributes] __attribute__ ((format(gnu_printf, 3, 4))); ^ 1 warning generated. We can convert from gnu_printf to printf without any side effects for two reasons: 1. All iavf_debug instances use standard printf formats, as pointed out by Miguel Ojeda at the below link, meaning gnu_printf is not strictly required. 2. However, GCC has aliased printf to gnu_printf on Linux since at least 2010 based on git history. From gcc/c-family/c-format.c: /* Attributes such as "printf" are equivalent to those such as "gnu_printf" unless this is overridden by a target. */ static const target_ovr_attr gnu_target_overrides_format_attributes[] = { { "gnu_printf", "printf" }, { "gnu_scanf", "scanf" }, { "gnu_strftime", "strftime" }, { "gnu_strfmon", "strfmon" }, { NULL, NULL } }; The mentioned override only happens on Windows (mingw32). Changing from gnu_printf to printf is a no-op for GCC and stops Clang from warning. Link: https://github.com/ClangBuiltLinux/linux/issues/111 Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> --- drivers/net/ethernet/intel/iavf/iavf_osdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)