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Message-ID: <alpine.DEB.2.20.1710132344590.3147@hadrien>
Date: Fri, 13 Oct 2017 23:48:25 +0200 (CEST)
From: Julia Lawall <julia.lawall@...6.fr>
To: Larry Finger <Larry.Finger@...inger.net>
cc: linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
kbuild-all@...org
Subject: Re: drivers/staging/rtlwifi/base.c:920:7-9: WARNING: possible
condition with no effect (if == else)
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@...org
> > > CC: linux-kernel@...r.kernel.org
> > > TO: Larry Finger <Larry.Finger@...inger.net>
> > > CC: "Greg Kroah-Hartman" <gregkh@...uxfoundation.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@...ltek.com>
> > > :::::: CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > >
> > > ---
> > > 0-DAY kernel test infrastructure Open Source Technology
> > > Center
> > > https://lists.01.org/pipermail/kbuild-all Intel
> > > Corporation
> > >
> >
>
>
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