Return-path: Received: from mail-we0-f176.google.com ([74.125.82.176]:58194 "EHLO mail-we0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753138AbaFHBPQ (ORCPT ); Sat, 7 Jun 2014 21:15:16 -0400 Received: by mail-we0-f176.google.com with SMTP id q59so4413781wes.35 for ; Sat, 07 Jun 2014 18:15:14 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <5393A7D0.2080700@lwfinger.net> References: <1402151419-18296-1-git-send-email-rickard_strandqvist@spectrumdigital.se> <1670424.dXK6NPb10R@al> <5393A7D0.2080700@lwfinger.net> Date: Sun, 8 Jun 2014 03:15:14 +0200 Message-ID: (sfid-20140608_031539_862340_3CBDEFA4) Subject: Re: [PATCH] net: wireless: rtlwifi: rtl8192de: hw.c: Cleaning up conjunction always evaluates to false From: Rickard Strandqvist To: Larry Finger Cc: Peter Wu , Chaoming Li , "John W. Linville" , linux-wireless@vger.kernel.org, Network Development , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi all Good. New patches are on the way :) Best regards Rickard Strandqvist 2014-06-08 2:01 GMT+02:00 Larry Finger : > On 06/07/2014 10:24 AM, Rickard Strandqvist wrote: >> >> Hi! >> >> Yes, 0x3 was one of the most likely :) >> But wanted someone who knows the code better would be heard. >> All agreed? Then I do a new patch. >> >> Looks like it is the same error in the files below, I'll fix them all them >> to. >> >> rtl8192cu/hw.c:1363: if ((bt_msr & 0xfc) == MSR_AP) >> rtl8192ce/hw.c:1209: if ((bt_msr & 0xfc) == MSR_AP) >> rtl8188ee/hw.c:1234: if ((bt_msr & 0xfc) == MSR_AP) >> rtl8192de/hw.c:1131: if ((bt_msr & 0xfc) == MSR_AP) >> >> >> Best regards >> Rickard Strandqvist >> >> >> 2014-06-07 17:02 GMT+02:00 Peter Wu : >>> >>> On Saturday 07 June 2014 16:30:19 Rickard Strandqvist wrote: >>>> >>>> Expression '(X & 0xfc) == 0x3' is always false >>> >>> >>> While this is true, I believe that some other mistake is made. >>> >>>> I chose to remove this code, because it will not make any difference. >>>> But obviously it is rather a properly designed if statement that is >>>> needed. >>>> >>>> This was partly found using a static code analysis program called >>>> cppcheck. >>>> >>>> Signed-off-by: Rickard Strandqvist >>>> >>>> --- >>>> drivers/net/wireless/rtlwifi/rtl8192de/hw.c | 5 +---- >>>> 1 file changed, 1 insertion(+), 4 deletions(-) >>>> >>>> diff --git a/drivers/net/wireless/rtlwifi/rtl8192de/hw.c >>>> b/drivers/net/wireless/rtlwifi/rtl8192de/hw.c >>>> index 2b08671..a1520d5 100644 >>>> --- a/drivers/net/wireless/rtlwifi/rtl8192de/hw.c >>>> +++ b/drivers/net/wireless/rtlwifi/rtl8192de/hw.c >>>> @@ -1128,10 +1128,7 @@ static int _rtl92de_set_media_status(struct >>>> ieee80211_hw *hw, >>>> } >>>> rtl_write_byte(rtlpriv, REG_CR + 2, bt_msr); >>>> rtlpriv->cfg->ops->led_control(hw, ledaction); >>>> - if ((bt_msr & 0xfc) == MSR_AP) >>> >>> >>> If you look a few lines up, then you see that bt_msr is OR-ed with MSR_AP >>> for AP interfaces. The 0xfc should be 0x03, see other drivers for >>> example: >>> >>> rtl8723ae/hw.c:1112: if ((bt_msr & 0x03) == MSR_AP) >>> rtl8723be/hw.c:1200: if ((bt_msr & 0x03) == MSR_AP) >>> rtl8192cu/hw.c:1363: if ((bt_msr & 0xfc) == MSR_AP) >>> rtl8192ce/hw.c:1209: if ((bt_msr & 0xfc) == MSR_AP) >>> rtl8188ee/hw.c:1234: if ((bt_msr & 0xfc) == MSR_AP) >>> rtl8192de/hw.c:1131: if ((bt_msr & 0xfc) == MSR_AP) >>> >>>> - rtl_write_byte(rtlpriv, REG_BCNTCFG + 1, 0x00); >>>> - else >>>> - rtl_write_byte(rtlpriv, REG_BCNTCFG + 1, 0x66); >>>> + rtl_write_byte(rtlpriv, REG_BCNTCFG + 1, 0x66); >>>> return 0; >>>> } > > > Peter, > > As you have learned here, automatically making changes suggested by some > tool may convert a visible bug into one that is invisible, and only found by > a detailed line-by-line examination of the code, and that is unlikely to > happen. Please be careful. > > From everything I see, the test in all drivers should be > > if ((bt_msr & MSR_AP) == MSR_AP) > > Larry >