Re: drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c:2022:1: warning: unused function 'mlxsw_afa_sampler_mirror_agent_get'
From: Nathan Chancellor
Date: Wed Sep 29 2021 - 12:39:55 EST
Hi Ido,
On Wed, Sep 29, 2021 at 12:44:16PM +0300, Ido Schimmel wrote:
> On Tue, Sep 28, 2021 at 09:06:54PM +0300, kernel test robot wrote:
> > All warnings (new ones prefixed by >>):
> >
> > static inline u32 mlxsw_##_type##_##_cname##_##_iname##_get(const char ^
> > <scratch space>:119:1: note: expanded from here
> > mlxsw_afa_polcnt_c_p_get
> > ^
>
> I saw your reply to a similar issue here [1] and I got the impression
> that you are leading the LLVM-related efforts, so I thought I will
> consult with you regarding a possible solution.
>
> The inline functions that clang is complaining about are generated by
> macros that make it easy to set/get fields in the payloads of
> configuration messages used to communicate with the device. It is
> possible that sometime we only set a field, but never retrieve its value
> such as in the warning above. This is very much intentional and not
> indicative of a function we forgot to remove.
>
> The patch below [2] adds the "__maybe_unused" keyword to these macros
> and makes clang happy [3].
>
> Is this acceptable or you suggest a different solution?
Yes, I would say this is a perfectly fine solution. The warning is there
to make you consider if you have forgotten to use or remove a function
depending on the context and if this is expected behavior, silencing the
compiler with the __maybe_unused attribute is the right thing to do. The
kernel does this for resume and suspend functions as CONFIG_PM might not
be set.
Cheers,
Nathan
> Thanks
>
> [1] https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx/thread/TIUWC7KZVTHGJKIZ4M3LI3JJYVAAINJX/
>
> [2]
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/item.h b/drivers/net/ethernet/mellanox/mlxsw/item.h
> index e92cadc98128..d2c8f436efb7 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/item.h
> +++ b/drivers/net/ethernet/mellanox/mlxsw/item.h
> @@ -290,13 +290,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u8 \
> +static inline u8 __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
> { \
> return __mlxsw_item_get8(buf, &__ITEM_NAME(_type, _cname, _iname), \
> index); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index, \
> u8 val) \
> { \
> @@ -311,11 +311,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u16 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf) \
> +static inline u16 __maybe_unused \
> +mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf) \
> { \
> return __mlxsw_item_get16(buf, &__ITEM_NAME(_type, _cname, _iname), 0); \
> } \
> -static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u16 val)\
> +static inline void __maybe_unused \
> +mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u16 val) \
> { \
> __mlxsw_item_set16(buf, &__ITEM_NAME(_type, _cname, _iname), 0, val); \
> }
> @@ -331,13 +333,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u16 \
> +static inline u16 __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
> { \
> return __mlxsw_item_get16(buf, &__ITEM_NAME(_type, _cname, _iname), \
> index); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index, \
> u16 val) \
> { \
> @@ -352,11 +354,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u32 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf) \
> +static inline u32 __maybe_unused \
> +mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf) \
> { \
> return __mlxsw_item_get32(buf, &__ITEM_NAME(_type, _cname, _iname), 0); \
> } \
> -static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u32 val)\
> +static inline void __maybe_unused \
> +mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u32 val) \
> { \
> __mlxsw_item_set32(buf, &__ITEM_NAME(_type, _cname, _iname), 0, val); \
> }
> @@ -372,13 +376,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u32 \
> +static inline u32 __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
> { \
> return __mlxsw_item_get32(buf, &__ITEM_NAME(_type, _cname, _iname), \
> index); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index, \
> u32 val) \
> { \
> @@ -393,11 +397,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u64 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf) \
> +static inline u64 __maybe_unused \
> +mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf) \
> { \
> return __mlxsw_item_get64(buf, &__ITEM_NAME(_type, _cname, _iname), 0); \
> } \
> -static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u64 val)\
> +static inline void __maybe_unused \
> +mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u64 val) \
> { \
> __mlxsw_item_set64(buf, &__ITEM_NAME(_type, _cname, _iname), 0, val); \
> }
> @@ -413,13 +419,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bits = _sizebits,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u64 \
> +static inline u64 __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
> { \
> return __mlxsw_item_get64(buf, &__ITEM_NAME(_type, _cname, _iname), \
> index); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index, \
> u64 val) \
> { \
> @@ -433,19 +439,19 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bytes = _sizebytes,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_memcpy_from(const char *buf, char *dst) \
> { \
> __mlxsw_item_memcpy_from(buf, dst, \
> &__ITEM_NAME(_type, _cname, _iname), 0); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf, const char *src) \
> { \
> __mlxsw_item_memcpy_to(buf, src, \
> &__ITEM_NAME(_type, _cname, _iname), 0); \
> } \
> -static inline char * \
> +static inline char * __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_data(char *buf) \
> { \
> return __mlxsw_item_data(buf, &__ITEM_NAME(_type, _cname, _iname), 0); \
> @@ -460,7 +466,7 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bytes = _sizebytes,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_memcpy_from(const char *buf, \
> unsigned short index, \
> char *dst) \
> @@ -468,7 +474,7 @@ mlxsw_##_type##_##_cname##_##_iname##_memcpy_from(const char *buf, \
> __mlxsw_item_memcpy_from(buf, dst, \
> &__ITEM_NAME(_type, _cname, _iname), index); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf, \
> unsigned short index, \
> const char *src) \
> @@ -476,7 +482,7 @@ mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf, \
> __mlxsw_item_memcpy_to(buf, src, \
> &__ITEM_NAME(_type, _cname, _iname), index); \
> } \
> -static inline char * \
> +static inline char * __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_data(char *buf, unsigned short index) \
> { \
> return __mlxsw_item_data(buf, \
> @@ -491,14 +497,14 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = { \
> .size = {.bytes = _sizebytes,}, \
> .name = #_type "_" #_cname "_" #_iname, \
> }; \
> -static inline u8 \
> +static inline u8 __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, u16 index) \
> { \
> return __mlxsw_item_bit_array_get(buf, \
> &__ITEM_NAME(_type, _cname, _iname), \
> index); \
> } \
> -static inline void \
> +static inline void __maybe_unused \
> mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u16 index, u8 val) \
> { \
> return __mlxsw_item_bit_array_set(buf, \
>
> [3]
> $ make -j8 CC=clang C=2 W=1 drivers/net/ethernet/mellanox/mlxsw/
> DESCEND bpf/resolve_btfids
> DESCEND objtool
> CHECK scripts/mod/empty.c
> CALL scripts/atomic/check-atomics.sh
> CALL scripts/checksyscalls.sh
> CHECK drivers/net/ethernet/mellanox/mlxsw/core.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/core_env.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/pci.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/i2c.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_router_xm.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum1_kvdl.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum2_kvdl.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_kvdl.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_ctcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_atcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum1_acl_tcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum2_acl_tcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_flow.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_matchall.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_fid.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_ipip.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_flex_actions.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_flex_keys.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum1_mr_tcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum2_mr_tcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_mr_tcam.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_nve.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_nve_vxlan.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_dpipe.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_trap.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_ethtool.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_policer.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_dcb.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c
> CHECK drivers/net/ethernet/mellanox/mlxsw/minimal.c