linux-kernel - Re: [PATCH v2] nvmem: rmem: Fix return value of rmem

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Date: Tue, 27 Feb 2024 12:27:09 +0530
From: Joy Chakraborty <joychakr@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, Rob Herring <robh@...nel.org>, 
	Nicolas Saenz Julienne <nsaenz@...nel.org>, linux-kernel@...r.kernel.org, manugautam@...gle.com, 
	stable@...r.kernel.org
Subject: Re: [PATCH v2] nvmem: rmem: Fix return value of rmem_read()

On Wed, Feb 7, 2024 at 8:33 PM Joy Chakraborty <joychakr@...gle.com> wrote:
>
> On Wed, Feb 7, 2024 at 3:04 PM Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> >
> > On Tue, Feb 06, 2024 at 05:22:15PM +0530, Joy Chakraborty wrote:
> > > > > Userspace will see a false error with nvmem cell reads from
> > > > > nvmem_cell_attr_read() in current code, which should be fixed on
> > > > > returning 0 for success.
> > > >
> > > > So maybe fix this all up to allow the read to return the actual amount
> > > > read?  That feels more "correct" to me.
> > > >
> > >
> > > If I change the behavior of the nvmem_reg_read_t callback to negative
> > > for error and number of bytes actually read for success then, other
> > > than the core driver I would also have to change all the
> > > nvmem-provider drivers.
> > > Is it okay to do so ?
> >
> > Sure, why not?  That seems like the correct fix to me, right?
>
> Sure, I can do that.
>
> Is it okay to change the if checks on the return code to "if (rc < 0)"
> instead of "if (rc)" as a fix for the immediate issue with how return
> value from rmem is handled which can be applied to older kernels.
> In a separate patch I can change the definition of nvmem_reg_read_t()
> to return ssize_t instead of int and make corresponding changes to
> nvmem-provider drivers.
>
> Does that sound okay ?

Hi Greg,

Sent a patch https://lore.kernel.org/all/20240219113149.2437990-2-joychakr@google.com/
to change the return type for read/write callbacks.
Do I mark that with the "Fixes:" tag as well ?
It affects a lot of files so might not be able to easily pick to an
older kernel when needed.

Thanks
Joy

> >
> > thanks,
> >
> > greg k-h
>
> Thanks
> Joy