There is no need to prefix macro parameters with underscores.
Remove the underscores.
Suggested-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v4:
- Update recently introduced FIELD_MODIFY() macro,
v3:
- New.
---
include/linux/bitfield.h | 106 +++++++++++++++++++--------------------
1 file changed, 53 insertions(+), 53 deletions(-)
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 5355f8f806a97974..7ff817bdae19b468 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -60,68 +60,68 @@
#define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
-#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
+#define __BF_FIELD_CHECK(mask, reg, val, 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_MSG(__builtin_constant_p(_val) ? \
- ~((_mask) >> __bf_shf(_mask)) & \
- (0 + (_val)) : 0, \
- _pfx "value too large for the field"); \
- BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
- __bf_cast_unsigned(_reg, ~0ull), \
- _pfx "type of reg too small for mask"); \
- __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
- (1ULL << __bf_shf(_mask))); \
+ 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_MSG(__builtin_constant_p(val) ? \
+ ~((mask) >> __bf_shf(mask)) & \
+ (0 + (val)) : 0, \
+ pfx "value too large for the field"); \
+ BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) > \
+ __bf_cast_unsigned(reg, ~0ull), \
+ pfx "type of reg too small for mask"); \
+ __BUILD_BUG_ON_NOT_POWER_OF_2((mask) + \
+ (1ULL << __bf_shf(mask))); \
})
/**
* FIELD_MAX() - produce the maximum value representable by a field
- * @_mask: shifted mask defining the field's length and position
+ * @mask: shifted mask defining the field's length and position
*
* FIELD_MAX() returns the maximum value that can be held in the field
- * specified by @_mask.
+ * specified by @mask.
*/
-#define FIELD_MAX(_mask) \
+#define FIELD_MAX(mask) \
({ \
- __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \
- (typeof(_mask))((_mask) >> __bf_shf(_mask)); \
+ __BF_FIELD_CHECK(mask, 0ULL, 0ULL, "FIELD_MAX: "); \
+ (typeof(mask))((mask) >> __bf_shf(mask)); \
})
/**
* FIELD_FIT() - check if value fits in the field
- * @_mask: shifted mask defining the field's length and position
- * @_val: value to test against the field
+ * @mask: shifted mask defining the field's length and position
+ * @val: value to test against the field
*
- * Return: true if @_val can fit inside @_mask, false if @_val is too big.
+ * Return: true if @val can fit inside @mask, false if @val is too big.
*/
-#define FIELD_FIT(_mask, _val) \
+#define FIELD_FIT(mask, val) \
({ \
- __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \
- !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
+ __BF_FIELD_CHECK(mask, 0ULL, 0ULL, "FIELD_FIT: "); \
+ !((((typeof(mask))val) << __bf_shf(mask)) & ~(mask)); \
})
/**
* FIELD_PREP() - prepare a bitfield element
- * @_mask: shifted mask defining the field's length and position
- * @_val: value to put in the field
+ * @mask: shifted mask defining the field's length and position
+ * @val: value to put in the field
*
* FIELD_PREP() masks and shifts up the value. The result should
* be combined with other fields of the bitfield using logical OR.
*/
-#define FIELD_PREP(_mask, _val) \
+#define FIELD_PREP(mask, val) \
({ \
- __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \
- ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \
+ __BF_FIELD_CHECK(mask, 0ULL, val, "FIELD_PREP: "); \
+ ((typeof(mask))(val) << __bf_shf(mask)) & (mask); \
})
#define __BF_CHECK_POW2(n) BUILD_BUG_ON_ZERO(((n) & ((n) - 1)) != 0)
/**
* FIELD_PREP_CONST() - prepare a constant bitfield element
- * @_mask: shifted mask defining the field's length and position
- * @_val: value to put in the field
+ * @mask: shifted mask defining the field's length and position
+ * @val: value to put in the field
*
* FIELD_PREP_CONST() masks and shifts up the value. The result should
* be combined with other fields of the bitfield using logical OR.
@@ -130,47 +130,47 @@
* be used in initializers. Error checking is less comfortable for this
* version, and non-constant masks cannot be used.
*/
-#define FIELD_PREP_CONST(_mask, _val) \
+#define FIELD_PREP_CONST(mask, val) \
( \
/* mask must be non-zero */ \
- BUILD_BUG_ON_ZERO((_mask) == 0) + \
+ BUILD_BUG_ON_ZERO((mask) == 0) + \
/* check if value fits */ \
- BUILD_BUG_ON_ZERO(~((_mask) >> __bf_shf(_mask)) & (_val)) + \
+ BUILD_BUG_ON_ZERO(~((mask) >> __bf_shf(mask)) & (val)) + \
/* check if mask is contiguous */ \
- __BF_CHECK_POW2((_mask) + (1ULL << __bf_shf(_mask))) + \
+ __BF_CHECK_POW2((mask) + (1ULL << __bf_shf(mask))) + \
/* and create the value */ \
- (((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask)) \
+ (((typeof(mask))(val) << __bf_shf(mask)) & (mask)) \
)
/**
* FIELD_GET() - extract a bitfield element
- * @_mask: shifted mask defining the field's length and position
- * @_reg: value of entire bitfield
+ * @mask: shifted mask defining the field's length and position
+ * @reg: value of entire bitfield
*
- * FIELD_GET() extracts the field specified by @_mask from the
- * bitfield passed in as @_reg by masking and shifting it down.
+ * FIELD_GET() extracts the field specified by @mask from the
+ * bitfield passed in as @reg by masking and shifting it down.
*/
-#define FIELD_GET(_mask, _reg) \
+#define FIELD_GET(mask, reg) \
({ \
- __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \
- (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
+ __BF_FIELD_CHECK(mask, reg, 0U, "FIELD_GET: "); \
+ (typeof(mask))(((reg) & (mask)) >> __bf_shf(mask)); \
})
/**
* FIELD_MODIFY() - modify a bitfield element
- * @_mask: shifted mask defining the field's length and position
- * @_reg_p: pointer to the memory that should be updated
- * @_val: value to store in the bitfield
+ * @mask: shifted mask defining the field's length and position
+ * @reg_p: pointer to the memory that should be updated
+ * @val: value to store in the bitfield
*
- * FIELD_MODIFY() modifies the set of bits in @_reg_p specified by @_mask,
- * by replacing them with the bitfield value passed in as @_val.
+ * FIELD_MODIFY() modifies the set of bits in @reg_p specified by @mask,
+ * by replacing them with the bitfield value passed in as @val.
*/
-#define FIELD_MODIFY(_mask, _reg_p, _val) \
+#define FIELD_MODIFY(mask, reg_p, val) \
({ \
- typecheck_pointer(_reg_p); \
- __BF_FIELD_CHECK(_mask, *(_reg_p), _val, "FIELD_MODIFY: "); \
- *(_reg_p) &= ~(_mask); \
- *(_reg_p) |= (((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask)); \
+ typecheck_pointer(reg_p); \
+ __BF_FIELD_CHECK(mask, *(reg_p), val, "FIELD_MODIFY: "); \
+ *(reg_p) &= ~(mask); \
+ *(reg_p) |= (((typeof(mask))(val) << __bf_shf(mask)) & (mask)); \
})
extern void __compiletime_error("value doesn't fit into mask")
--
2.43.0On Fri, Oct 17, 2025 at 12:54:09PM +0200, Geert Uytterhoeven wrote:
> There is no need to prefix macro parameters with underscores.
> Remove the underscores.
>
> Suggested-by: David Laight <david.laight.linux@gmail.com>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> v4:
> - Update recently introduced FIELD_MODIFY() macro,
>
> v3:
> - New.
> ---
> include/linux/bitfield.h | 106 +++++++++++++++++++--------------------
> 1 file changed, 53 insertions(+), 53 deletions(-)
>
> diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
> index 5355f8f806a97974..7ff817bdae19b468 100644
> --- a/include/linux/bitfield.h
> +++ b/include/linux/bitfield.h
> @@ -60,68 +60,68 @@
>
> #define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
>
> -#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
> +#define __BF_FIELD_CHECK(mask, reg, val, 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_MSG(__builtin_constant_p(_val) ? \
> - ~((_mask) >> __bf_shf(_mask)) & \
> - (0 + (_val)) : 0, \
> - _pfx "value too large for the field"); \
> - BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
> - __bf_cast_unsigned(_reg, ~0ull), \
> - _pfx "type of reg too small for mask"); \
> - __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
> - (1ULL << __bf_shf(_mask))); \
> + 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_MSG(__builtin_constant_p(val) ? \
> + ~((mask) >> __bf_shf(mask)) & \
> + (0 + (val)) : 0, \
> + pfx "value too large for the field"); \
> + BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) > \
> + __bf_cast_unsigned(reg, ~0ull), \
> + pfx "type of reg too small for mask"); \
> + __BUILD_BUG_ON_NOT_POWER_OF_2((mask) + \
> + (1ULL << __bf_shf(mask))); \
> })
Hi Geert,
Thanks for the series!
I agree that underscored parameters are excessive. But fixing them has
a side effect of wiping the history, which is a bad thing.
I would prefer to save a history over following a rule that seemingly
is not written down. Let's keep this untouched for now, and if there
will be a need to move the code, we can drop underscores as well.
Meanwhile you (and David) can propose a corresponding rule in
coding-style.rst and a checkpatch warning. That way we at least will
stop merging a new code of that style.
Thanks,
Yury
Hi Yury,
On Fri, 17 Oct 2025 at 18:37, Yury Norov <yury.norov@gmail.com> wrote:
> On Fri, Oct 17, 2025 at 12:54:09PM +0200, Geert Uytterhoeven wrote:
> > There is no need to prefix macro parameters with underscores.
> > Remove the underscores.
> >
> > Suggested-by: David Laight <david.laight.linux@gmail.com>
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > ---
> > v4:
> > - Update recently introduced FIELD_MODIFY() macro,
> > --- a/include/linux/bitfield.h
> > +++ b/include/linux/bitfield.h
> > @@ -60,68 +60,68 @@
> >
> > #define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
> >
> > -#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
> > +#define __BF_FIELD_CHECK(mask, reg, val, 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_MSG(__builtin_constant_p(_val) ? \
> > - ~((_mask) >> __bf_shf(_mask)) & \
> > - (0 + (_val)) : 0, \
> > - _pfx "value too large for the field"); \
> > - BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
> > - __bf_cast_unsigned(_reg, ~0ull), \
> > - _pfx "type of reg too small for mask"); \
> > - __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
> > - (1ULL << __bf_shf(_mask))); \
> > + 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_MSG(__builtin_constant_p(val) ? \
> > + ~((mask) >> __bf_shf(mask)) & \
> > + (0 + (val)) : 0, \
> > + pfx "value too large for the field"); \
> > + BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) > \
> > + __bf_cast_unsigned(reg, ~0ull), \
> > + pfx "type of reg too small for mask"); \
> > + __BUILD_BUG_ON_NOT_POWER_OF_2((mask) + \
> > + (1ULL << __bf_shf(mask))); \
> > })
>
> I agree that underscored parameters are excessive. But fixing them has
> a side effect of wiping the history, which is a bad thing.
>
> I would prefer to save a history over following a rule that seemingly
> is not written down. Let's keep this untouched for now, and if there
> will be a need to move the code, we can drop underscores as well.
Fair enough.
So I assume you are fine with not having underscored parameters in
new code, like in [PATCH v4 2/4]?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
> > I agree that underscored parameters are excessive. But fixing them has > > a side effect of wiping the history, which is a bad thing. > > > > I would prefer to save a history over following a rule that seemingly > > is not written down. Let's keep this untouched for now, and if there > > will be a need to move the code, we can drop underscores as well. > > Fair enough. > So I assume you are fine with not having underscored parameters in > new code, like in [PATCH v4 2/4]? Yes, sure.
© 2016 - 2026 Red Hat, Inc.