[v2,2/2] bitfield.h: split up __BF_FIELD_CHECK macro

Message ID 20200708230402.1644819-3-ndesaulniers@google.com
State New
Headers show
Series
  • bitfield.h cleanups
Related show

Commit Message

Nick Desaulniers July 8, 2020, 11:04 p.m.
This macro has a few expansion sites that pass literal 0s as parameters.
Split these up so that we do the precise checks where we care about
them.

Suggested-by: Alex Elder <elder@linaro.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

---
Changes V1-V2:
* New patch in v2.
* Rebased on 0001.

 .../netronome/nfp/nfpcore/nfp_nsp_eth.c       | 11 ++++----
 include/linux/bitfield.h                      | 26 +++++++++++++------
 2 files changed, 24 insertions(+), 13 deletions(-)

-- 
2.27.0.383.g050319c2ae-goog

Comments

Alex Elder July 9, 2020, 2:11 a.m. | #1
On 7/8/20 6:04 PM, Nick Desaulniers wrote:
> This macro has a few expansion sites that pass literal 0s as parameters.

> Split these up so that we do the precise checks where we care about

> them.

> 

> Suggested-by: Alex Elder <elder@linaro.org>

> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>


I do like this better.  It makes it more obvious when only
the mask is being verified (in FIELD_FIT() for example).
I also appreciate that you distinguished the register
checks from the value checks.
- field masks must be (2^x - 1) << y, x > 0, and constant
- values must be representable within a field mask
- registers must be able to represent the field mask

Reviewed-by: Alex Elder <elder@linaro.org>


> ---

> Changes V1-V2:

> * New patch in v2.

> * Rebased on 0001.

> 

>  .../netronome/nfp/nfpcore/nfp_nsp_eth.c       | 11 ++++----

>  include/linux/bitfield.h                      | 26 +++++++++++++------

>  2 files changed, 24 insertions(+), 13 deletions(-)

> 

> diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

> index 311a5be25acb..938fc733fccb 100644

> --- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

> +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

> @@ -492,11 +492,12 @@ nfp_eth_set_bit_config(struct nfp_nsp *nsp, unsigned int raw_idx,

>  	return 0;

>  }

>  

> -#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)	\

> -	({								\

> -		__BF_FIELD_CHECK(mask, 0ULL, val, "NFP_ETH_SET_BIT_CONFIG: "); \

> -		nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask), \

> -				       val, ctrl_bit);			\

> +#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)		\

> +	({									\

> +		__BF_FIELD_CHECK_MASK(mask, "NFP_ETH_SET_BIT_CONFIG: ");	\

> +		__BF_FIELD_CHECK_VAL(mask, val, "NFP_ETH_SET_BIT_CONFIG: ");	\

> +		nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask),	\

> +				       val, ctrl_bit);				\

>  	})

>  

>  /**

> diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h

> index 4e035aca6f7e..79651867beb3 100644

> --- a/include/linux/bitfield.h

> +++ b/include/linux/bitfield.h

> @@ -41,18 +41,26 @@

>  

>  #define __bf_shf(x) (__builtin_ffsll(x) - 1)

>  

> -#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx)			\

> +#define __BF_FIELD_CHECK_MASK(_mask, _pfx)				\

>  	({								\

>  		BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask),		\

>  				 _pfx "mask is not constant");		\

>  		BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero");	\

> +		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\

> +					      (1ULL << __bf_shf(_mask))); \

> +	})

> +

> +#define __BF_FIELD_CHECK_VAL(_mask, _val, _pfx)				\

> +	({								\

>  		BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ?		\

>  				 ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \

>  				 _pfx "value too large for the field"); \

> -		BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull,		\

> +	})

> +

> +#define __BF_FIELD_CHECK_REG(_mask, _reg, _pfx)				\

> +	({								\

> +		BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ULL,		\

>  				 _pfx "type of reg too small for mask"); \

> -		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\

> -					      (1ULL << __bf_shf(_mask))); \

>  	})

>  

>  /**

> @@ -64,7 +72,7 @@

>   */

>  #define FIELD_MAX(_mask)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_MAX: ");		\

>  		(typeof(_mask))((_mask) >> __bf_shf(_mask));		\

>  	})

>  

> @@ -77,7 +85,7 @@

>   */

>  #define FIELD_FIT(_mask, _val)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_FIT: ");		\

>  		!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \

>  	})

>  

> @@ -91,7 +99,8 @@

>   */

>  #define FIELD_PREP(_mask, _val)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_PREP: ");		\

> +		__BF_FIELD_CHECK_VAL(_mask, _val, "FIELD_PREP: ");	\

>  		((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);	\

>  	})

>  

> @@ -105,7 +114,8 @@

>   */

>  #define FIELD_GET(_mask, _reg)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_GET: ");		\

> +		__BF_FIELD_CHECK_REG(_mask, _reg,  "FIELD_GET: ");	\

>  		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask));	\

>  	})

>  

>
Alex Elder July 9, 2020, 2:11 a.m. | #2
On 7/8/20 6:04 PM, Nick Desaulniers wrote:
> This macro has a few expansion sites that pass literal 0s as parameters.

> Split these up so that we do the precise checks where we care about

> them.

> 

> Suggested-by: Alex Elder <elder@linaro.org>

> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>


I do like this better.  It makes it more obvious when only
the mask is being verified (in FIELD_FIT() for example).
I also appreciate that you distinguished the register
checks from the value checks.
- field masks must be (2^x - 1) << y, x > 0, and constant
- values must be representable within a field mask
- registers must be able to represent the field mask

Reviewed-by: Alex Elder <elder@linaro.org>


> ---

> Changes V1-V2:

> * New patch in v2.

> * Rebased on 0001.

> 

>  .../netronome/nfp/nfpcore/nfp_nsp_eth.c       | 11 ++++----

>  include/linux/bitfield.h                      | 26 +++++++++++++------

>  2 files changed, 24 insertions(+), 13 deletions(-)

> 

> diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

> index 311a5be25acb..938fc733fccb 100644

> --- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

> +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

> @@ -492,11 +492,12 @@ nfp_eth_set_bit_config(struct nfp_nsp *nsp, unsigned int raw_idx,

>  	return 0;

>  }

>  

> -#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)	\

> -	({								\

> -		__BF_FIELD_CHECK(mask, 0ULL, val, "NFP_ETH_SET_BIT_CONFIG: "); \

> -		nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask), \

> -				       val, ctrl_bit);			\

> +#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)		\

> +	({									\

> +		__BF_FIELD_CHECK_MASK(mask, "NFP_ETH_SET_BIT_CONFIG: ");	\

> +		__BF_FIELD_CHECK_VAL(mask, val, "NFP_ETH_SET_BIT_CONFIG: ");	\

> +		nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask),	\

> +				       val, ctrl_bit);				\

>  	})

>  

>  /**

> diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h

> index 4e035aca6f7e..79651867beb3 100644

> --- a/include/linux/bitfield.h

> +++ b/include/linux/bitfield.h

> @@ -41,18 +41,26 @@

>  

>  #define __bf_shf(x) (__builtin_ffsll(x) - 1)

>  

> -#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx)			\

> +#define __BF_FIELD_CHECK_MASK(_mask, _pfx)				\

>  	({								\

>  		BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask),		\

>  				 _pfx "mask is not constant");		\

>  		BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero");	\

> +		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\

> +					      (1ULL << __bf_shf(_mask))); \

> +	})

> +

> +#define __BF_FIELD_CHECK_VAL(_mask, _val, _pfx)				\

> +	({								\

>  		BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ?		\

>  				 ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \

>  				 _pfx "value too large for the field"); \

> -		BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull,		\

> +	})

> +

> +#define __BF_FIELD_CHECK_REG(_mask, _reg, _pfx)				\

> +	({								\

> +		BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ULL,		\

>  				 _pfx "type of reg too small for mask"); \

> -		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\

> -					      (1ULL << __bf_shf(_mask))); \

>  	})

>  

>  /**

> @@ -64,7 +72,7 @@

>   */

>  #define FIELD_MAX(_mask)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_MAX: ");		\

>  		(typeof(_mask))((_mask) >> __bf_shf(_mask));		\

>  	})

>  

> @@ -77,7 +85,7 @@

>   */

>  #define FIELD_FIT(_mask, _val)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_FIT: ");		\

>  		!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \

>  	})

>  

> @@ -91,7 +99,8 @@

>   */

>  #define FIELD_PREP(_mask, _val)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_PREP: ");		\

> +		__BF_FIELD_CHECK_VAL(_mask, _val, "FIELD_PREP: ");	\

>  		((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);	\

>  	})

>  

> @@ -105,7 +114,8 @@

>   */

>  #define FIELD_GET(_mask, _reg)						\

>  	({								\

> -		__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: ");	\

> +		__BF_FIELD_CHECK_MASK(_mask, "FIELD_GET: ");		\

> +		__BF_FIELD_CHECK_REG(_mask, _reg,  "FIELD_GET: ");	\

>  		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask));	\

>  	})

>  

>

Patch

diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
index 311a5be25acb..938fc733fccb 100644
--- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
+++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
@@ -492,11 +492,12 @@  nfp_eth_set_bit_config(struct nfp_nsp *nsp, unsigned int raw_idx,
 	return 0;
 }
 
-#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)	\
-	({								\
-		__BF_FIELD_CHECK(mask, 0ULL, val, "NFP_ETH_SET_BIT_CONFIG: "); \
-		nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask), \
-				       val, ctrl_bit);			\
+#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)		\
+	({									\
+		__BF_FIELD_CHECK_MASK(mask, "NFP_ETH_SET_BIT_CONFIG: ");	\
+		__BF_FIELD_CHECK_VAL(mask, val, "NFP_ETH_SET_BIT_CONFIG: ");	\
+		nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask),	\
+				       val, ctrl_bit);				\
 	})
 
 /**
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 4e035aca6f7e..79651867beb3 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -41,18 +41,26 @@ 
 
 #define __bf_shf(x) (__builtin_ffsll(x) - 1)
 
-#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx)			\
+#define __BF_FIELD_CHECK_MASK(_mask, _pfx)				\
 	({								\
 		BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask),		\
 				 _pfx "mask is not constant");		\
 		BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero");	\
+		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\
+					      (1ULL << __bf_shf(_mask))); \
+	})
+
+#define __BF_FIELD_CHECK_VAL(_mask, _val, _pfx)				\
+	({								\
 		BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ?		\
 				 ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
 				 _pfx "value too large for the field"); \
-		BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull,		\
+	})
+
+#define __BF_FIELD_CHECK_REG(_mask, _reg, _pfx)				\
+	({								\
+		BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ULL,		\
 				 _pfx "type of reg too small for mask"); \
-		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\
-					      (1ULL << __bf_shf(_mask))); \
 	})
 
 /**
@@ -64,7 +72,7 @@ 
  */
 #define FIELD_MAX(_mask)						\
 	({								\
-		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: ");	\
+		__BF_FIELD_CHECK_MASK(_mask, "FIELD_MAX: ");		\
 		(typeof(_mask))((_mask) >> __bf_shf(_mask));		\
 	})
 
@@ -77,7 +85,7 @@ 
  */
 #define FIELD_FIT(_mask, _val)						\
 	({								\
-		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: ");	\
+		__BF_FIELD_CHECK_MASK(_mask, "FIELD_FIT: ");		\
 		!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
 	})
 
@@ -91,7 +99,8 @@ 
  */
 #define FIELD_PREP(_mask, _val)						\
 	({								\
-		__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");	\
+		__BF_FIELD_CHECK_MASK(_mask, "FIELD_PREP: ");		\
+		__BF_FIELD_CHECK_VAL(_mask, _val, "FIELD_PREP: ");	\
 		((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);	\
 	})
 
@@ -105,7 +114,8 @@ 
  */
 #define FIELD_GET(_mask, _reg)						\
 	({								\
-		__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: ");	\
+		__BF_FIELD_CHECK_MASK(_mask, "FIELD_GET: ");		\
+		__BF_FIELD_CHECK_REG(_mask, _reg,  "FIELD_GET: ");	\
 		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask));	\
 	})