netdev - Re: [PATCH net-next v3] net: wwan: t7xx: fix GFP_KERNEL usage in spin

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Date:   Sat, 21 May 2022 19:26:34 +0200
From:   Loic Poulain <loic.poulain@...aro.org>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Ziyang Xuan <william.xuanziyang@...wei.com>,
        chandrashekar.devegowda@...el.com,
        chiranjeevi.rapolu@...ux.intel.com, davem@...emloft.net,
        edumazet@...gle.com, haijun.liu@...iatek.com,
        johannes@...solutions.net, linuxwwan@...el.com,
        m.chetan.kumar@...ux.intel.com, netdev@...r.kernel.org,
        pabeni@...hat.com, ricardo.martinez@...ux.intel.com,
        ryazanov.s.a@...il.com
Subject: Re: [PATCH net-next v3] net: wwan: t7xx: fix GFP_KERNEL usage in
 spin_lock context

Le sam. 21 mai 2022 à 03:01, Jakub Kicinski <kuba@...nel.org> a écrit :
>
> On Fri, 20 May 2022 17:25:56 -0700 Jakub Kicinski wrote:
> > On Thu, 19 May 2022 09:29:12 +0200 Loic Poulain wrote:
> > > On Thu, 19 May 2022 at 09:26, Ziyang Xuan <william.xuanziyang@...wei.com> wrote:
> > > >
> > > > t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
> > > > context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
> > > > GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
> > > >
> > > > Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
> > > > remove the spin_lock from t7xx_cldma_clear_rxq().
> > > >
> > > > Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
> > > > Suggested-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
> > > > Signed-off-by: Ziyang Xuan <william.xuanziyang@...wei.com>
> > >
> > > Reviewed-by: Loic Poulain <loic.poulain@...aro.org>
> >
> > Wait, you reviewed two different fixes for the same issue?
> > Please say something when that happens I thought both are needed :/


Right, I've actually overlooked that the other patch has only one
atomic user, which becomes useless with this change.

>
>
> FWIW I pushed out the other one before I realized (they both apply
> without conflicts so I thought they fixed different issues)
> If this one is preferred please respin and squash a revert of
>
>
> 9ee152ee3ee3 into it.

Yes this one is preferred, I'll respin it. Sorry for this.

Thanks,
Loic