When building with Clang we encounter the following warning:
| drivers/net/ethernet/amd/xgbe/xgbe-dcb.c:234:42: error: format specifies
| type 'unsigned char' but the argument has type '__u16' (aka 'unsigned
| short') [-Werror,-Wformat] pfc->pfc_cap, pfc->pfc_en, pfc->mbc,
| pfc->delay);
pfc->pfc_cap , pfc->pfc_cn, pfc->mbc are all of type `u8` while pfc->delay is
of type `u16`. The correct format specifiers `%hh[u|x]` were used for
the first three but not for pfc->delay, which is causing the warning
above.
Variadic functions (printf-like) undergo default argument promotion.
Documentation/core-api/printk-formats.rst specifically recommends using
the promoted-to-type's format flag. In this case `%d` (or `%x` to
maintain hex representation) should be used since both u8's and u16's
are fully representable by an int.
Moreover, C11 6.3.1.1 states:
(https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf) `If an int
can represent all values of the original type ..., the value is
converted to an int; otherwise, it is converted to an unsigned int.
These are called the integer promotions.`
Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Justin Stitt <[email protected]>
---
For clarification, the first three parameters given to netif_dbg did NOT
cause a -Wformat warning. I changed them simply to follow what the
standard and documentation recommend.
drivers/net/ethernet/amd/xgbe/xgbe-dcb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c b/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
index 895d35639129..c68ace804e37 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
@@ -230,7 +230,7 @@ static int xgbe_dcb_ieee_setpfc(struct net_device *netdev,
struct xgbe_prv_data *pdata = netdev_priv(netdev);
netif_dbg(pdata, drv, netdev,
- "cap=%hhu, en=%#hhx, mbc=%hhu, delay=%hhu\n",
+ "cap=%d, en=%#x, mbc=%d, delay=%d\n",
pfc->pfc_cap, pfc->pfc_en, pfc->mbc, pfc->delay);
/* Check PFC for supported number of traffic classes */
--
2.37.0.rc0.161.g10f37bed90-goog
On Fri, Jul 8, 2022 at 4:27 PM Justin Stitt <[email protected]> wrote:
>
> When building with Clang we encounter the following warning:
> | drivers/net/ethernet/amd/xgbe/xgbe-dcb.c:234:42: error: format specifies
> | type 'unsigned char' but the argument has type '__u16' (aka 'unsigned
> | short') [-Werror,-Wformat] pfc->pfc_cap, pfc->pfc_en, pfc->mbc,
> | pfc->delay);
>
> pfc->pfc_cap , pfc->pfc_cn, pfc->mbc are all of type `u8` while pfc->delay is
> of type `u16`. The correct format specifiers `%hh[u|x]` were used for
> the first three but not for pfc->delay, which is causing the warning
> above.
>
> Variadic functions (printf-like) undergo default argument promotion.
> Documentation/core-api/printk-formats.rst specifically recommends using
> the promoted-to-type's format flag. In this case `%d` (or `%x` to
> maintain hex representation) should be used since both u8's and u16's
> are fully representable by an int.
>
> Moreover, C11 6.3.1.1 states:
> (https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf) `If an int
> can represent all values of the original type ..., the value is
> converted to an int; otherwise, it is converted to an unsigned int.
> These are called the integer promotions.`
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/378
> Signed-off-by: Justin Stitt <[email protected]>
Thanks for the patch, this fixes an instance of -Wformat I observe for
x86_64 allmodconfig. I thought you had already fixed this file up?
https://lore.kernel.org/llvm/[email protected]/
which was merged. I'm guessing that was from a defconfig, while this
was from an allmodconfig?
Seems like there's a bunch of config ifdef'ery around the definition
of netif_dbg.
Either way, thanks for the patches and
Reviewed-by: Nick Desaulniers <[email protected]>
Tested-by: Nick Desaulniers <[email protected]>
> ---
> For clarification, the first three parameters given to netif_dbg did NOT
> cause a -Wformat warning. I changed them simply to follow what the
> standard and documentation recommend.
>
> drivers/net/ethernet/amd/xgbe/xgbe-dcb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c b/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
> index 895d35639129..c68ace804e37 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
> @@ -230,7 +230,7 @@ static int xgbe_dcb_ieee_setpfc(struct net_device *netdev,
> struct xgbe_prv_data *pdata = netdev_priv(netdev);
>
> netif_dbg(pdata, drv, netdev,
> - "cap=%hhu, en=%#hhx, mbc=%hhu, delay=%hhu\n",
> + "cap=%d, en=%#x, mbc=%d, delay=%d\n",
> pfc->pfc_cap, pfc->pfc_en, pfc->mbc, pfc->delay);
>
> /* Check PFC for supported number of traffic classes */
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>
--
Thanks,
~Nick Desaulniers
On Fri, Jul 8, 2022 at 4:48 PM Nick Desaulniers <[email protected]> wrote:
>
> On Fri, Jul 8, 2022 at 4:27 PM Justin Stitt <[email protected]> wrote:
> >
> > When building with Clang we encounter the following warning:
> > | drivers/net/ethernet/amd/xgbe/xgbe-dcb.c:234:42: error: format specifies
> > | type 'unsigned char' but the argument has type '__u16' (aka 'unsigned
> > | short') [-Werror,-Wformat] pfc->pfc_cap, pfc->pfc_en, pfc->mbc,
> > | pfc->delay);
> >
> > pfc->pfc_cap , pfc->pfc_cn, pfc->mbc are all of type `u8` while pfc->delay is
> > of type `u16`. The correct format specifiers `%hh[u|x]` were used for
> > the first three but not for pfc->delay, which is causing the warning
> > above.
> >
> > Variadic functions (printf-like) undergo default argument promotion.
> > Documentation/core-api/printk-formats.rst specifically recommends using
> > the promoted-to-type's format flag. In this case `%d` (or `%x` to
> > maintain hex representation) should be used since both u8's and u16's
> > are fully representable by an int.
> >
> > Moreover, C11 6.3.1.1 states:
> > (https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf) `If an int
> > can represent all values of the original type ..., the value is
> > converted to an int; otherwise, it is converted to an unsigned int.
> > These are called the integer promotions.`
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/378
> > Signed-off-by: Justin Stitt <[email protected]>
>
> Thanks for the patch, this fixes an instance of -Wformat I observe for
> x86_64 allmodconfig. I thought you had already fixed this file up?
> https://lore.kernel.org/llvm/[email protected]/
> which was merged. I'm guessing that was from a defconfig, while this
> was from an allmodconfig?
> Seems like there's a bunch of config ifdef'ery around the definition
> of netif_dbg.
Definitely different across configs but ALSO files are
ever-so-slightly different:
amd/xgbe/xgbe-drv.c _v.s_ amd/xgbe/xgbe-dcb.c
>
> Either way, thanks for the patches and
>
> Reviewed-by: Nick Desaulniers <[email protected]>
> Tested-by: Nick Desaulniers <[email protected]>
>
> > ---
> > For clarification, the first three parameters given to netif_dbg did NOT
> > cause a -Wformat warning. I changed them simply to follow what the
> > standard and documentation recommend.
> >
> > drivers/net/ethernet/amd/xgbe/xgbe-dcb.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c b/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
> > index 895d35639129..c68ace804e37 100644
> > --- a/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
> > +++ b/drivers/net/ethernet/amd/xgbe/xgbe-dcb.c
> > @@ -230,7 +230,7 @@ static int xgbe_dcb_ieee_setpfc(struct net_device *netdev,
> > struct xgbe_prv_data *pdata = netdev_priv(netdev);
> >
> > netif_dbg(pdata, drv, netdev,
> > - "cap=%hhu, en=%#hhx, mbc=%hhu, delay=%hhu\n",
> > + "cap=%d, en=%#x, mbc=%d, delay=%d\n",
> > pfc->pfc_cap, pfc->pfc_en, pfc->mbc, pfc->delay);
> >
> > /* Check PFC for supported number of traffic classes */
> > --
> > 2.37.0.rc0.161.g10f37bed90-goog
> >
>
>
> --
> Thanks,
> ~Nick Desaulniers
Hello:
This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <[email protected]>:
On Fri, 8 Jul 2022 16:26:53 -0700 you wrote:
> When building with Clang we encounter the following warning:
> | drivers/net/ethernet/amd/xgbe/xgbe-dcb.c:234:42: error: format specifies
> | type 'unsigned char' but the argument has type '__u16' (aka 'unsigned
> | short') [-Werror,-Wformat] pfc->pfc_cap, pfc->pfc_en, pfc->mbc,
> | pfc->delay);
>
> pfc->pfc_cap , pfc->pfc_cn, pfc->mbc are all of type `u8` while pfc->delay is
> of type `u16`. The correct format specifiers `%hh[u|x]` were used for
> the first three but not for pfc->delay, which is causing the warning
> above.
>
> [...]
Here is the summary with links:
- amd-xgbe: fix clang -Wformat warnings
https://git.kernel.org/netdev/net-next/c/2afe46474ba3
You are awesome, thank you!
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