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| author | Johannes Berg <johannes.berg@intel.com> | 2024-02-23 12:01:46 +0300 |
|---|---|---|
| committer | Kalle Valo <kvalo@kernel.org> | 2024-02-28 14:53:39 +0300 |
| commit | 416eb60317c64676d158dffea150762930ec008f (patch) | |
| tree | 6f94b9fe5c6fd25e408ef1ff9783241aabbcd31a | |
| parent | a7e178259c5bc900da762b33d3a20b7ee1206f07 (diff) | |
| download | linux-416eb60317c64676d158dffea150762930ec008f.tar.xz | |
bitfield: suppress "dubious: x & !y" sparse warning
There's a somewhat common pattern of using FIELD_PREP()
even for single bits, e.g.
cmd->info1 |= FIELD_PREP(HTT_SRNG_SETUP_CMD_INFO1_RING_FLAGS_MSI_SWAP,
!!(params.flags & HAL_SRNG_FLAGS_MSI_SWAP));
which might as well be written as
if (params.flags & HAL_SRNG_FLAGS_MSI_SWAP)
cmd->info1 |= HTT_SRNG_SETUP_CMD_INFO1_RING_FLAGS_MSI_SWAP;
(since info1 is fully initialized to start with), but in
a long chain of FIELD_PREP() this really seems fine.
However, it triggers a sparse warning, in the check in
the macro for whether a constant value fits into the mask,
as this contains a "& (_val)". In this case, this really
is always intentional, so just suppress the warning by
adding "0+" to the expression, indicating explicitly that
this is correct.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240223100146.d243b6b1a9a1.I033828b1187c6bccf086e31400f7e933bb8373e7@changeid
| -rw-r--r-- | include/linux/bitfield.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index ebfa12f69501..63928f173223 100644 --- a/include/linux/bitfield.h +++ b/include/linux/bitfield.h @@ -66,7 +66,8 @@ _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)) & (_val) : 0, \ + ~((_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), \ |