linux-kernel - Re: [PATCH] misc: rtsx: Set setting

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Date:   Thu, 19 May 2022 14:24:49 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Tom Rix <trix@...hat.com>
Cc:     Ricky WU <ricky_wu@...ltek.com>, miquel.raynal@...tlin.com,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "ndesaulniers@...gle.com" <ndesaulniers@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>
Subject: Re: [PATCH] misc: rtsx: Set setting_reg2 before use.

On Thu, May 19, 2022 at 02:18:59PM -0700, Tom Rix wrote:
> 
> On 5/19/22 1:57 PM, Nathan Chancellor wrote:
> > On Tue, May 17, 2022 at 08:10:17AM +0000, Ricky WU wrote:
> > > > -----Original Message-----
> > > > From: Kai-Heng Feng <kai.heng.feng@...onical.com>
> > > > Sent: Tuesday, May 17, 2022 9:53 AM
> > > > To: Tom Rix <trix@...hat.com>
> > > > Cc: Nathan Chancellor <nathan@...nel.org>; arnd@...db.de;
> > > > gregkh@...uxfoundation.org; ndesaulniers@...gle.com; Ricky WU
> > > > <ricky_wu@...ltek.com>; linux-kernel@...r.kernel.org; llvm@...ts.linux.dev
> > > > Subject: Re: [PATCH] misc: rtsx: Set setting_reg2 before use.
> > > > 
> > > > On Tue, May 17, 2022 at 1:06 AM Tom Rix <trix@...hat.com> wrote:
> > > > > 
> > > > > On 5/16/22 8:56 AM, Nathan Chancellor wrote:
> > > > > > On Mon, May 16, 2022 at 09:00:47AM -0400, Tom Rix wrote:
> > > > > > > The clang build fails with
> > > > > > > rts5261.c:406:13: error: variable 'setting_reg2' is used uninitialized
> > > > whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
> > > > > > >           } else if (efuse_valid == 0) {
> > > > > > >                      ^~~~~~~~~~~~~~~~
> > > > > > > 
> > > > > > > setting_reg2 is set in this block
> > > > > > >     if (efuse_valid == 2 || efuse_valid == 3) { ..
> > > > > > >     } else if (efuse_valid == 0) {
> > > > > > >       // default
> > > > > > > ..
> > > > > > >     }
> > > > > > > But efuse_valid can also have a value of 1.
> > > > > > > Change the 'else if' to 'else' to make the second block the default.
> > > > > > > 
> > > > > > > Fixes: b1c5f3085149 ("misc: rtsx: add rts5261 efuse function")
> > > > > > > Signed-off-by: Tom Rix <trix@...hat.com>
> > > > > > I am not sure if this fix is correct from a functional standpoint (i.e.
> > > > > > is treating efuse_valid == 1 the same as efuse_valid == 0 correct?)
> > > > > > but it is better than not handling this value altogether. For what
> > > > > > it's
> > > > > > worth:
> > > > > I looked at how the code used to work, this seemed better than
> > > > > initializing to NULL.
> > > > Or maybe use a single if block?
> > > > 
> > > > u16 setting_reg1 =PCR_SETTING_REG1 , setting_reg2 =
> > > > PCR_SETTING_REG2; ...
> > > > if ((efuse_valid == 2 || efuse_valid == 3) && (valid != 3) {
> > > >      setting_reg1 = PCR_SETTING_REG4;
> > > >      setting_reg2 = PCR_SETTING_REG5;
> > > > }
> > > > 
> > > > Kai-Heng
> > > > 
> > > > > > Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> > > > > > 
> > > > > > As a side note, it is unfortunate that this change made it into
> > > > > > -next when there was an outstanding report about this warning:
> > > > >   From the clang side, this is a build break and my static analysis
> > > > > infra goes down.
> > > > > 
> > > > > These build breaks seem to happening every week, is there a precommit
> > > > > clang gating test that could be done for -next ?
> > > > > 
> > > > > Tom
> > > > > 
> > > > > > https://lore.kernel.org/202205100220.WyAyhKap-lkp@intel.com/
> > > > > > 
> > > > > > > ---
> > > > > > >    drivers/misc/cardreader/rts5261.c | 2 +-
> > > > > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > > > 
> > > > > > > diff --git a/drivers/misc/cardreader/rts5261.c
> > > > > > > b/drivers/misc/cardreader/rts5261.c
> > > > > > > index 749cc5a46d13..f22634b14dc8 100644
> > > > > > > --- a/drivers/misc/cardreader/rts5261.c
> > > > > > > +++ b/drivers/misc/cardreader/rts5261.c
> > > > > > > @@ -403,7 +403,7 @@ static void rts5261_init_from_hw(struct rtsx_pcr
> > > > *pcr)
> > > > > > >                       setting_reg1 = PCR_SETTING_REG4;
> > > > > > >                       setting_reg2 = PCR_SETTING_REG5;
> > > > > > >               }
> > > > > > > -    } else if (efuse_valid == 0) {
> > > > > > > +    } else {
> > > > > > >               // default
> > > > > > >               setting_reg1 = PCR_SETTING_REG1;
> > > > > > >               setting_reg2 = PCR_SETTING_REG2;
> > > Sorry for the trouble
> > > here can be changed to
> > > ...
> > > } else if (efuse_valid == 0) {
> > > 		// default
> > > 		setting_reg1 = PCR_SETTING_REG1;
> > > 		setting_reg2 = PCR_SETTING_REG2;
> > > } else {
> > >   return;
> > > }
> > > Because other values are invalid
> > Tom, were you going to send a v2 of this?
> 
> No.
> 
> Miquèl has the best fix.
> 
> https://lore.kernel.org/lkml/20220518170920.4db16990@xps-13/

Different warning/patch I think? There are too many of these flying
around as of late :( this one doesn't have a new version from what I can
tell.

I do see a fix for that one available:

https://lore.kernel.org/20220519132300.424095-1-miquel.raynal@bootlin.com/

Cheers,
Nathan