From e36488c83b6d871b35dd555afb2d434bd61687cf Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 17 Aug 2018 15:43:36 -0700 Subject: [PATCH] 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@arndb.de Fixes: 514c30696fbc ("iwlwifi: add support for IEEE802.11ax") Signed-off-by: Arnd Bergmann Cc: Masahiro Yamada Cc: Johannes Berg Cc: Jakub Kicinski Cc: Andy Shevchenko Cc: Al Viro Cc: David Laight Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/bitfield.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 65a6981eef7b..3f1ef4450a7c 100644 --- a/include/linux/bitfield.h +++ b/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"); \