From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Berg <johannes@sipsolutions.net>,
Jakub Kicinski <jakub.kicinski@netronome.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bitfield: avoid gcc-8 -Wint-in-bool-context warning
Date: Tue, 14 Aug 2018 08:57:34 +0900 [thread overview]
Message-ID: <CAK7LNASVE-vZhGyAsWg8YmPb8P-sucwPVOUt5qsfVwZQuHg9gw@mail.gmail.com> (raw)
In-Reply-To: <20180813220950.194841-1-arnd@arndb.de>
2018-08-14 7:09 GMT+09:00 Arnd Bergmann <arnd@arndb.de>:
> 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,
How about fixing the root cause
in drivers/net/wireless/intel/iwlwifi/fw/api/rx.h ?
#define IWL_RX_HE_PHY_SIBG_SYM_OR_USER_NUM_MASK 0x1e00000000ULL
enum iwl_rx_he_phy looks really strange.
Passing enum to FIELD_GET is odd,
so I prefer keeping this warned.
> 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.
>
> Fixes: 514c30696fbc ("iwlwifi: add support for IEEE802.11ax")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> 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"); \
> --
> 2.18.0
>
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2018-08-13 23:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-13 22:09 [PATCH] bitfield: avoid gcc-8 -Wint-in-bool-context warning Arnd Bergmann
2018-08-13 23:57 ` Masahiro Yamada [this message]
2018-08-14 7:56 ` Johannes Berg
2018-08-14 8:43 ` Arnd Bergmann
2018-08-14 9:31 ` Masahiro Yamada
2018-08-14 10:06 ` David Laight
2018-08-14 11:08 ` Arnd Bergmann
2018-08-14 11:10 ` Johannes Berg
2018-08-14 13:09 ` David Laight
2018-08-14 23:11 ` Andrew Morton
2018-08-14 23:13 ` Andrew Morton
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