From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: bitfield: avoid gcc-8 -Wint-in-bool-context warning
Passing an enum into FIELD_GET() produces a long but harmless warning on
newer compilers:
from include/linux/linkage.h:7,
from include/linux/kernel.h:7,
from include/linux/skbuff.h:17,
from include/linux/if_ether.h:23,
from include/linux/etherdevice.h:25,
from drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c:63:
drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c: In function 'iwl_mvm_rx_mpdu_mq':
include/linux/bitfield.h:56:20: error: enum constant in boolean context [-Werror=int-in-bool-context]
BUILD_BUG_ON_MSG(!(_mask), _pfx "mask is zero"); \
^
...
include/linux/bitfield.h:103:3: note: in expansion of macro '__BF_FIELD_CHECK'
__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \
^~~~~~~~~~~~~~~~
drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c:1025:21: note: in expansion of macro 'FIELD_GET'
le16_encode_bits(FIELD_GET(IWL_RX_HE_PHY_SIBG_SYM_OR_USER_NUM_MASK,
The problem here is that the caller has no idea how the macro gets
expanding, leading to a false-positive. It can be trivially avoided by
doing a comparison against zero.
This only recently started appearing as the iwlwifi driver was patched to
use FIELD_GET.
Link: http://lkml.kernel.org/r/20180813220950.194841-1-arnd@xxxxxxxx
Fixes: 514c30696fbc ("iwlwifi: add support for IEEE802.11ax")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/bitfield.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/bitfield.h~bitfield-avoid-gcc-8-wint-in-bool-context-warning
+++ a/include/linux/bitfield.h
@@ -53,7 +53,7 @@
({ \
BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \
_pfx "mask is not constant"); \
- BUILD_BUG_ON_MSG(!(_mask), _pfx "mask is zero"); \
+ BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \
BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \
~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
_pfx "value too large for the field"); \
_
