From: Christian Lamparter <chunkeey@gmail.com>
To: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org
Subject: Re: [PATCH] carl9170: fix enum compare splat
Date: Mon, 10 Jun 2019 13:45:31 +0200 [thread overview]
Message-ID: <1601416.I41mb68Wgz@debian64> (raw)
In-Reply-To: <87pnnlncll.fsf@codeaurora.org>
On Monday, June 10, 2019 9:06:30 AM CEST Kalle Valo wrote:
> Christian Lamparter <chunkeey@gmail.com> writes:
>
> > This patch fixes a noisy warning triggered by -Wenum-compare
> >
> > |main.c:1390:31: warning: comparison between ‘enum nl80211_ac’
> > | and ‘enum ar9170_txq’ [-Wenum-compare]
> > | BUILD_BUG_ON(NL80211_NUM_ACS > __AR9170_NUM_TXQ);
> > | ^
> > | [...]
> >
> > This is a little bit unfortunate, since the number of queues
> > (hence NL80211_NUM_ACS) is a constant based on the IEEE 802.11
> > (much like IEEE80211_NUM_ACS) and __AR9170_NUM_TXQ is more or
> > less defined by the AR9170 hardware.
>
> Is the warning enabled by default? TBH I'm not seeing how useful this
> warning is for kernel development.
It is included in the "-Wall" (which is coming from "KBUILD_CFLAGS"
in the main Makefile).
I tried debian's gcc starting from 4.6 to the lastest 8.3. They all
complain about it in various degrees.
https://gcc.gnu.org/onlinedocs/gcc-4.6.0/gcc/Warning-Options.html#Warning-Options
> > --- a/drivers/net/wireless/ath/carl9170/main.c
> > +++ b/drivers/net/wireless/ath/carl9170/main.c
> > @@ -1387,7 +1387,7 @@ static int carl9170_op_conf_tx(struct ieee80211_hw *hw,
> > int ret;
> >
> > BUILD_BUG_ON(ARRAY_SIZE(ar9170_qmap) != __AR9170_NUM_TXQ);
> > - BUILD_BUG_ON(NL80211_NUM_ACS > __AR9170_NUM_TXQ);
> > + BUILD_BUG_ON((size_t)NL80211_NUM_ACS > (size_t)__AR9170_NUM_TXQ);
>
> IMHO this just makes the code worse. Does it make sense to workaround
> (stupid) compiler warnings like this?
True. What's worse: This isn't really code. The BUILD_BUG_ON Macro is there
to guard but it's getting compiled away. I could also just drop it.
next prev parent reply other threads:[~2019-06-10 11:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-08 14:49 [PATCH] carl9170: fix enum compare splat Christian Lamparter
2019-06-08 14:49 ` [RFC PATCH v2] ath9k: add loader for AR92XX (and older) pci(e) Christian Lamparter
2019-06-09 13:28 ` Julian Calaby
2019-06-08 14:49 ` [PATCH v2] carl9170: fix misuse of device driver API Christian Lamparter
2019-06-10 14:12 ` Alan Stern
2019-06-27 17:47 ` Kalle Valo
2019-06-10 7:06 ` [PATCH] carl9170: fix enum compare splat Kalle Valo
2019-06-10 11:45 ` Christian Lamparter [this message]
2019-06-18 12:11 ` Kalle Valo
2019-06-20 14:41 ` Christian Lamparter
2019-06-26 14:17 ` Kalle Valo
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