linux-kernel - Re: [PATCH] net/chelsio/libcxgb: Add __percpu annotations to libcxgb

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Message-ID: <CAFULd4aye+mGTV1CJp5Coq0Qr2DvwOezpd5-hxWbF4-xR5aj_Q@mail.gmail.com>
Date: Wed, 31 Jul 2024 12:06:18 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH] net/chelsio/libcxgb: Add __percpu annotations to libcxgb_ppm.c

On Wed, Jul 31, 2024 at 11:35 AM Simon Horman <horms@...nel.org> wrote:
>
> On Tue, Jul 30, 2024 at 02:58:19PM +0200, Uros Bizjak wrote:
> > Compiling libcxgb_ppm.c results in several sparse warnings:
> >
> > libcxgb_ppm.c:368:15: warning: incorrect type in assignment (different address spaces)
> > libcxgb_ppm.c:368:15:    expected struct cxgbi_ppm_pool *pools
> > libcxgb_ppm.c:368:15:    got void [noderef] __percpu *_res
> > libcxgb_ppm.c:374:48: warning: incorrect type in initializer (different address spaces)
> > libcxgb_ppm.c:374:48:    expected void const [noderef] __percpu *__vpp_verify
> > libcxgb_ppm.c:374:48:    got struct cxgbi_ppm_pool *
> > libcxgb_ppm.c:484:19: warning: incorrect type in assignment (different address spaces)
> > libcxgb_ppm.c:484:19:    expected struct cxgbi_ppm_pool [noderef] __percpu *pool
> > libcxgb_ppm.c:484:19:    got struct cxgbi_ppm_pool *[assigned] pool
> > libcxgb_ppm.c:511:21: warning: incorrect type in argument 1 (different address spaces)
> > libcxgb_ppm.c:511:21:    expected void [noderef] __percpu *__pdata
> > libcxgb_ppm.c:511:21:    got struct cxgbi_ppm_pool *[assigned] pool
> >
> > Add __percpu annotation to *pools and *pool percpu pointers and to
> > ppm_alloc_cpu_pool() function that returns percpu pointer to fix
> > these warnings.
> >
> > Compile tested only, but there is no difference in the resulting object file.
> >
> > Signed-off-by: Uros Bizjak <ubizjak@...il.com>
> > Cc: "David S. Miller" <davem@...emloft.net>
> > Cc: Eric Dumazet <edumazet@...gle.com>
> > Cc: Jakub Kicinski <kuba@...nel.org>
> > Cc: Paolo Abeni <pabeni@...hat.com>
> > ---
> >  drivers/net/ethernet/chelsio/libcxgb/libcxgb_ppm.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/chelsio/libcxgb/libcxgb_ppm.c b/drivers/net/ethernet/chelsio/libcxgb/libcxgb_ppm.c
> > index 854d87e1125c..01d776113500 100644
> > --- a/drivers/net/ethernet/chelsio/libcxgb/libcxgb_ppm.c
> > +++ b/drivers/net/ethernet/chelsio/libcxgb/libcxgb_ppm.c
> > @@ -342,10 +342,10 @@ int cxgbi_ppm_release(struct cxgbi_ppm *ppm)
> >  }
> >  EXPORT_SYMBOL(cxgbi_ppm_release);
> >
> > -static struct cxgbi_ppm_pool *ppm_alloc_cpu_pool(unsigned int *total,
> > -                                              unsigned int *pcpu_ppmax)
> > +static struct cxgbi_ppm_pool __percpu *ppm_alloc_cpu_pool(unsigned int *total,
> > +                                                       unsigned int *pcpu_ppmax)
>
> Let's keep to less than 80 columns wide, as is still preferred for
> Networking code. Perhaps in this case:
>
> static struct cxgbi_ppm_pool __percpu *
> ppm_alloc_cpu_pool(unsigned int *total, unsigned int *pcpu_ppmax)

Hm, the original is exactly what sparse dumped, IMO code dumps should
be left as they were dumped.

> Also, I do observe that this is an old driver, so the value
> of cleaning it is perhaps limited.

It broke my strict percpu checker with allyesconfig. Fixing it was
trivial and resulted in no object code changes.

> But the above aside, this looks good to me.

Thanks,
Uros.