linux-kernel - Re: [PATCH v3 2/2] ubi: expose the volume CRC check skip flag

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Date:   Mon, 02 Jul 2018 08:54:09 +0200
From:   Richard Weinberger <richard@....at>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Quentin Schulz <quentin.schulz@...tlin.com>, dedekind1@...il.com,
        dwmw2@...radead.org, computersforpeace@...il.com,
        marek.vasut@...il.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, thomas.petazzoni@...tlin.com
Subject: Re: [PATCH v3 2/2] ubi: expose the volume CRC check skip flag

Am Montag, 2. Juli 2018, 08:52:27 CEST schrieb Boris Brezillon:
> On Mon, 2 Jul 2018 08:44:33 +0200
> Quentin Schulz <quentin.schulz@...tlin.com> wrote:
> 
> > Hi Richard, Boris,
> > 
> > On Sun, Jul 01, 2018 at 10:50:41PM +0200, Richard Weinberger wrote:
> > > Am Sonntag, 1. Juli 2018, 22:33:47 CEST schrieb Boris Brezillon:  
> > > > On Sun, 01 Jul 2018 21:35:57 +0200
> > > > Richard Weinberger <richard@....at> wrote:
> > > >   
> > > > > Quentin,
> > > > > 
> > > > > Am Donnerstag, 28. Juni 2018, 09:40:53 CEST schrieb Quentin Schulz:  
> > > > > > Now that we have the logic for skipping CRC check for static UBI volumes
> > > > > > in the core, let's expose it to users.
> > > > > > 
> > > > > > This makes use of a padding byte in the volume description data
> > > > > > structure as a flag. This flag only tell for now whether we should skip
> > > > > > the CRC check of a volume.
> > > > > > 
> > > > > > This checks the UBI volume for which we are trying to skip the CRC check
> > > > > > is static.
> > > > > > 
> > > > > > Suggested-by: Boris Brezillon <boris.brezillon@...tlin.com>
> > > > > > Signed-off-by: Quentin Schulz <quentin.schulz@...tlin.com>
> > > > > > Reviewed-by: Boris Brezillon <boris.brezillon@...tlin.com>
> > > > > > ---
> > > > > >  drivers/mtd/ubi/cdev.c      |  4 ++++
> > > > > >  drivers/mtd/ubi/vmt.c       |  3 +++
> > > > > >  include/uapi/mtd/ubi-user.h | 16 ++++++++++++++--
> > > > > >  3 files changed, 21 insertions(+), 2 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
> > > > > > index 45c3296..3eea1df 100644
> > > > > > --- a/drivers/mtd/ubi/cdev.c
> > > > > > +++ b/drivers/mtd/ubi/cdev.c
> > > > > > @@ -622,6 +622,10 @@ static int verify_mkvol_req(const struct ubi_device *ubi,
> > > > > >  	    req->vol_type != UBI_STATIC_VOLUME)
> > > > > >  		goto bad;
> > > > > >  
> > > > > > +	if (req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG &&  
> > > > 
> > > > Oops, missed that req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG check was
> > > > missing parens (checkpatch --strict should complain about that).  
> > > 
> > > Latest when building my local branch or in linux-next we had noticed.
> > > No need to worry.
> > >    
> > > > > > +	    req->vol_type != UBI_STATIC_VOLUME)
> > > > > > +		goto bad;    
> > > > > 
> > > > > We should also reject unknown flags here.  
> > > > 
> > > > I agree.  
> > 
> > Should I send another version of my patches for it?

Yes. Please.

> Yes please, respin your series with this additional check. Just define
> 
> #define UBI_VOL_VALID_FLGS	(UBI_VOL_SKIP_CRC_CHECK_FLG)
> 
> and then, in verify_mkvol_req() add
> 
> 	if (req->flags & ~UBI_VOL_VALID_FLGS)
> 		goto bad;

Yep.
 
> > Same for
> > parenthesis around the flags masking above?
> 
> No need to fix that one (unless Richard cares), as it seems I had it
> wrong.

Nah. If both gcc and checkpatch don't complain, let's keep it as-is.

Thanks,
//richard