[PATCH] mtd: add MEMREAD ioctl

[Miquel Raynal]

Hi Michał,

kernel at kempniu.pl wrote on Thu, 30 Sep 2021 15:54:07 +0200:

> > > > > > I remember discussing search a new READ ioctl with Sascha Hauer a few
> > > > > > years back, but I can't find the discussion...      
> > > > 
> > > > I think this is the thread in question:
> > > > 
> > > >     https://www.infradead.org/pipermail/linux-mtd/2016-April/thread.html#67085
> > > > 
> > > > In fact, it looks like Boris beat me to preparing a draft patch adding a
> > > > MEMREAD ioctl by some five years:
> > > > 
> > > >     https://www.infradead.org/pipermail/linux-mtd/2016-April/067187.html    
> > > 
> > > Exactly the one I was referring to. Note that this patch still contains
> > > the unbounded malloc which I think is worth fixing, but other than
> > > that and the addition of ECC stats, it looks pretty similar to yours.  
> 
> Right, thanks.
> 
> > > > I guess the big question from my perspective is: should I revive Boris'
> > > > original effort on the MEMREAD ioctl (which returns more detailed
> > > > bitflip stats in the structure passed by user space) or would that be a
> > > > waste of time because the subsystem will be switched over wholesale to a
> > > > new way of doing I/O (mtd_io_op) in the foreseeable future and therefore
> > > > exposing yet another ioctl to user space today would be frowned upon?
> > > >     
> > > 
> > > That's not my call to make, but I think those 2 things are orthogonal
> > > and can be addressed separately.  
> > 
> > Agreed.  
> 
> Thank you both - it sounds like I should start working on a v2 that will
> make the new MEMREAD ioctl return more detailed ECC statistics to user
> space.
> 
> Boris, I think a Suggested-by tag crediting you is in order for both the
> unbounded malloc issue and the MEMREAD ioctl, but submitting-patches.rst
> says I should not add this tag without your permission.  So, are you
> okay with me adding it?
> 
> Miquel, as for the unbounded malloc issue, should I address this in a
> separate (preliminary) patch or rather submit a two-patch v2 series
> (unbounded malloc fix + new MEMREAD ioctl)?

Both work as long as you keep the changes in different commits :)

Thanks,
Miquèl