From: Julia Lawall <julia.lawall@lip6.fr>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
kbuild-all@01.org
Subject: Re: drivers/staging/rtlwifi/base.c:920:7-9: WARNING: possible condition with no effect (if == else)
Date: Fri, 13 Oct 2017 23:48:25 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1710132344590.3147@hadrien> (raw)
In-Reply-To: <9449a43b-2e02-f326-f5b1-7a55852ccb5b@lwfinger.net>
On Fri, 13 Oct 2017, Larry Finger wrote:
> Julia,
>
> On 10/13/2017 08:55 AM, Julia Lawall wrote:
> > It seems that the then and else branches of the conditions on lines 920
> > and 932 are the same.
>
> I think line 923 should be using RTL_RC_VHT_RATE_2SS_MCS8 rather than
> RTL_RC_VHT_RATE_2SS_MCS9, but I have sent an inquiry to my contact at Realtek
> to check.
OK, thanks. The realtek code has a surprisingly large number of these
kinds of problems, for example, the following from
(drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8723b2ant.c):
if ((wifi_rssi_state == BTC_RSSI_STATE_HIGH) ||
(wifi_rssi_state == BTC_RSSI_STATE_STAY_HIGH)) {
btc8723b2ant_sw_mechanism(btcoexist, true, false,
false, false);
} else {
btc8723b2ant_sw_mechanism(btcoexist, true, false,
false, false);
}
I wondered if the code is generated, and the generator has a policy of
just doing the last "then" branch if all of the known tests fail.
I could send a complete list of such issues, if they are of interest.
julia
>
> Thanks,
>
> Larry
>
> > On Fri, 13 Oct 2017, kbuild test robot wrote:
> >
> > > CC: kbuild-all@01.org
> > > CC: linux-kernel@vger.kernel.org
> > > TO: Larry Finger <Larry.Finger@lwfinger.net>
> > > CC: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
> > >
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > > master
> > > head: 3d7882769b5dc929690f96e0c318c29b97f51018
> > > commit: 5b5ab4cb5cda824ef59e0511ac5d585f35f1a1a6 staging: r8822be: Add
> > > Makefiles and Kconfig for new driver
> > > date: 8 weeks ago
> > > :::::: branch date: 12 hours ago
> > > :::::: commit date: 8 weeks ago
> > >
> > > > > drivers/staging/rtlwifi/base.c:920:7-9: WARNING: possible condition
> > > > > with no effect (if == else)
> > > drivers/staging/rtlwifi/base.c:932:7-9: WARNING: possible condition
> > > with no effect (if == else)
> > >
> > > #
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5b5ab4cb5cda824ef59e0511ac5d585f35f1a1a6
> > > git remote add linus
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > > git remote update linus
> > > git checkout 5b5ab4cb5cda824ef59e0511ac5d585f35f1a1a6
> > > vim +920 drivers/staging/rtlwifi/base.c
> > >
> > > 56bde846 Ping-Ke Shih 2017-08-17 905
> > > 56bde846 Ping-Ke Shih 2017-08-17 906 static u8
> > > _rtl_get_vht_highest_n_rate(struct ieee80211_hw *hw,
> > > 56bde846 Ping-Ke Shih 2017-08-17 907
> > > struct ieee80211_sta *sta)
> > > 56bde846 Ping-Ke Shih 2017-08-17 908 {
> > > 56bde846 Ping-Ke Shih 2017-08-17 909 struct rtl_priv *rtlpriv =
> > > rtl_priv(hw);
> > > 56bde846 Ping-Ke Shih 2017-08-17 910 struct rtl_phy *rtlphy =
> > > &rtlpriv->phy;
> > > 56bde846 Ping-Ke Shih 2017-08-17 911 u8 hw_rate;
> > > 56bde846 Ping-Ke Shih 2017-08-17 912 u16 tx_mcs_map =
> > > le16_to_cpu(sta->vht_cap.vht_mcs.tx_mcs_map);
> > > 56bde846 Ping-Ke Shih 2017-08-17 913
> > > 56bde846 Ping-Ke Shih 2017-08-17 914 if ((get_rf_type(rtlphy) ==
> > > RF_2T2R) &&
> > > 56bde846 Ping-Ke Shih 2017-08-17 915 (tx_mcs_map & 0x000c) !=
> > > 0x000c) {
> > > 56bde846 Ping-Ke Shih 2017-08-17 916 if ((tx_mcs_map &
> > > 0x000c) >> 2 ==
> > > 56bde846 Ping-Ke Shih 2017-08-17 917
> > > IEEE80211_VHT_MCS_SUPPORT_0_7)
> > > 56bde846 Ping-Ke Shih 2017-08-17 918 hw_rate =
> > > 56bde846 Ping-Ke Shih 2017-08-17 919
> > > rtlpriv->cfg->maps[RTL_RC_VHT_RATE_2SS_MCS7];
> > > 56bde846 Ping-Ke Shih 2017-08-17 @920 else if ((tx_mcs_map
> > > & 0x000c) >> 2 ==
> > > 56bde846 Ping-Ke Shih 2017-08-17 921
> > > IEEE80211_VHT_MCS_SUPPORT_0_8)
> > > 56bde846 Ping-Ke Shih 2017-08-17 922 hw_rate =
> > > 56bde846 Ping-Ke Shih 2017-08-17 923
> > > rtlpriv->cfg->maps[RTL_RC_VHT_RATE_2SS_MCS9];
> > > 56bde846 Ping-Ke Shih 2017-08-17 924 else
> > > 56bde846 Ping-Ke Shih 2017-08-17 925 hw_rate =
> > > 56bde846 Ping-Ke Shih 2017-08-17 926
> > > rtlpriv->cfg->maps[RTL_RC_VHT_RATE_2SS_MCS9];
> > > 56bde846 Ping-Ke Shih 2017-08-17 927 } else {
> > > 56bde846 Ping-Ke Shih 2017-08-17 928 if ((tx_mcs_map &
> > > 0x0003) ==
> > > 56bde846 Ping-Ke Shih 2017-08-17 929
> > > IEEE80211_VHT_MCS_SUPPORT_0_7)
> > > 56bde846 Ping-Ke Shih 2017-08-17 930 hw_rate =
> > > 56bde846 Ping-Ke Shih 2017-08-17 931
> > > rtlpriv->cfg->maps[RTL_RC_VHT_RATE_1SS_MCS7];
> > > 56bde846 Ping-Ke Shih 2017-08-17 932 else if ((tx_mcs_map
> > > & 0x0003) ==
> > > 56bde846 Ping-Ke Shih 2017-08-17 933
> > > IEEE80211_VHT_MCS_SUPPORT_0_8)
> > > 56bde846 Ping-Ke Shih 2017-08-17 934 hw_rate =
> > > 56bde846 Ping-Ke Shih 2017-08-17 935
> > > rtlpriv->cfg->maps[RTL_RC_VHT_RATE_1SS_MCS9];
> > > 56bde846 Ping-Ke Shih 2017-08-17 936 else
> > > 56bde846 Ping-Ke Shih 2017-08-17 937 hw_rate =
> > > 56bde846 Ping-Ke Shih 2017-08-17 938
> > > rtlpriv->cfg->maps[RTL_RC_VHT_RATE_1SS_MCS9];
> > > 56bde846 Ping-Ke Shih 2017-08-17 939 }
> > > 56bde846 Ping-Ke Shih 2017-08-17 940
> > > 56bde846 Ping-Ke Shih 2017-08-17 941 return hw_rate;
> > > 56bde846 Ping-Ke Shih 2017-08-17 942 }
> > > 56bde846 Ping-Ke Shih 2017-08-17 943
> > >
> > > :::::: The code at line 920 was first introduced by commit
> > > :::::: 56bde846304ea05d5f8c8de0e3a42627a7a92be6 staging: r8822be: Add
> > > existing rtlwifi and rtl_pci parts for new driver
> > >
> > > :::::: TO: Ping-Ke Shih <pkshih@realtek.com>
> > > :::::: CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > >
> > > ---
> > > 0-DAY kernel test infrastructure Open Source Technology
> > > Center
> > > https://lists.01.org/pipermail/kbuild-all Intel
> > > Corporation
> > >
> >
>
>
prev parent reply other threads:[~2017-10-13 21:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201710132012.kptCgENA%fengguang.wu@intel.com>
2017-10-13 13:55 ` Julia Lawall
2017-10-13 18:11 ` Larry Finger
2017-10-13 21:48 ` Julia Lawall [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.DEB.2.20.1710132344590.3147@hadrien \
--to=julia.lawall@lip6.fr \
--cc=Larry.Finger@lwfinger.net \
--cc=gregkh@linuxfoundation.org \
--cc=kbuild-all@01.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®