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

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Message-ID: <YoavUdiAJXPqsU7Q@dev-arch.thelio-3990X>
Date:   Thu, 19 May 2022 13:57:53 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Ricky WU <ricky_wu@...ltek.com>
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Tom Rix <trix@...hat.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 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?

Cheers,
Nathan