netdev - Re: [PATCH net-next v3 08/12] net: stmmac: Pass stmmac

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 10 Apr 2023 16:24:22 -0500
From:   Andrew Halaney <ahalaney@...hat.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     linux-kernel@...r.kernel.org, agross@...nel.org,
        andersson@...nel.org, konrad.dybcio@...aro.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, vkoul@...nel.org,
        bhupesh.sharma@...aro.org, wens@...e.org, jernej.skrabec@...il.com,
        samuel@...lland.org, mturquette@...libre.com,
        peppe.cavallaro@...com, alexandre.torgue@...s.st.com,
        joabreu@...opsys.com, mcoquelin.stm32@...il.com,
        richardcochran@...il.com, linux@...linux.org.uk, veekhee@...le.com,
        tee.min.tan@...ux.intel.com, mohammad.athari.ismail@...el.com,
        jonathanh@...dia.com, ruppala@...dia.com, bmasney@...hat.com,
        andrey.konovalov@...aro.org, linux-arm-msm@...r.kernel.org,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, ncai@...cinc.com,
        jsuraj@....qualcomm.com, hisunil@...cinc.com, echanude@...hat.com
Subject: Re: [PATCH net-next v3 08/12] net: stmmac: Pass stmmac_priv in some
 callbacks

On Fri, Apr 07, 2023 at 12:34:53PM -0500, Andrew Halaney wrote:
> On Sat, Apr 01, 2023 at 05:06:21PM +0200, Simon Horman wrote:
> > On Fri, Mar 31, 2023 at 04:45:45PM -0500, Andrew Halaney wrote:
> > > Passing stmmac_priv to some of the callbacks allows hwif implementations
> > > to grab some data that platforms can customize. Adjust the callbacks
> > > accordingly in preparation of such a platform customization.
> > > 
> > > Signed-off-by: Andrew Halaney <ahalaney@...hat.com>
> > 
> > ...
> > 
> > >  #define stmmac_reset(__priv, __args...) \
> > > @@ -223,59 +240,59 @@ struct stmmac_dma_ops {
> > >  #define stmmac_dma_init(__priv, __args...) \
> > >  	stmmac_do_void_callback(__priv, dma, init, __args)
> > >  #define stmmac_init_chan(__priv, __args...) \
> > > -	stmmac_do_void_callback(__priv, dma, init_chan, __args)
> > > +	stmmac_do_void_callback(__priv, dma, init_chan, __priv, __args)
> > 
> > Hi Andrew,
> > 
> > Rather than maintaining these macros can we just get rid of them?
> > I'd be surprised if things aren't nicer with functions in their place [1].
> > 
> > f.e., we now have (__priv, ..., __priv, ...) due to a generalisation
> >       that seems to take a lot more than it gives.
> > 
> > [1] https://lore.kernel.org/linux-arm-kernel/ZBst1SzcIS4j+t46@corigine.com/
> > 
> 
> Thanks for the pointer. I think that makes sense, I'll take that
> approach for these functions (and maybe in a follow-up series I'll
> tackle all of them just because the lack of consistency will eat me up).
> 

I tried taking this approach for a spin, and I'm not so sure about it
now!

1. Implementing the functions as static inline requires us to know
   about stmmac_priv, but that's getting into circular dependency land
2. You could define them in hwif.c, but then they're not inlined
3. There's still a good bit of boilerplate that's repeated all over
   with the approach. Ignoring 1 above, you get something like this:

static inline int stmmac_init_chan(struct stmmac_priv *priv,
				   void __iomem *ioaddr,
				   struct stmmac_dma_cfg *dma_cfg, u32 chan)
{
	if (priv->hw->dma && priv->hw->dma->init_chan) {
		priv->hw->dma->init_chan(priv, ioaddr, dma_cfg, chan);
		return 0;
	}
	return -EINVAL;
}

that is then repeated for every function... which is making me actually
appreciate the macros some for reducing boilerplate.

Am I suffering from a case of holiday brain, and 1-3 above are silly
points with obvious answers, or do they make you reconsider continuing
with the current approach in hwif.h?

Thanks,
Andrew