linux-kernel - Re: [PATCH v3] PCI: dwc: fix scheduling while atomic issues

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Message-ID: <20180913104914.GA2051@e107981-ln.cambridge.arm.com>
Date:   Thu, 13 Sep 2018 11:49:14 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Jisheng Zhang <Jisheng.Zhang@...aptics.com>
Cc:     Jingoo Han <jingoohan1@...il.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3] PCI: dwc: fix scheduling while atomic issues

On Thu, Sep 13, 2018 at 06:29:54PM +0800, Jisheng Zhang wrote:
> Hi Lorenzo,
> 
> On Thu, 13 Sep 2018 10:15:34 +0100 Lorenzo Pieralisi wrote:
> 
> > On Mon, Sep 10, 2018 at 04:57:22PM +0800, Jisheng Zhang wrote:
> > > Hi all,
> > > 
> > > On Wed, 29 Aug 2018 11:04:08 +0800 Jisheng Zhang wrote:
> > >   
> > > > When programming inbound/outbound atu, we call usleep_range() after
> > > > each checking PCIE_ATU_ENABLE bit. Unfortunately, the atu programming
> > > > can be called in atomic context:
> > > > 
> > > > inbound atu programming could be called through
> > > > pci_epc_write_header()  
> > > >   =>dw_pcie_ep_write_header()
> > > >     =>dw_pcie_prog_inbound_atu()    
> > > > 
> > > > outbound atu programming could be called through
> > > > pci_bus_read_config_dword()  
> > > >   =>dw_pcie_rd_conf()
> > > >     =>dw_pcie_prog_outbound_atu()    
> > > > 
> > > > Fix this issue by calling mdelay() instead.  
> > > 
> > > Any comments about this patch?
> > > 
> > > Thanks,
> > > Jisheng
> > >   
> > > > 
> > > > Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
> > > > Fixes: d8bbeb39fbf3 ("PCI: designware: Wait for iATU enable")  
> > 
> > Can you split it into two patches and repost it please ? It will make
> > everyone's life easier to backport it if there is need, I will apply
> > then.
> 
> IIUC, the purpose of this split is to make the backport to stable easier. If
> so, I realise that the Fixes tags were not enough, we missed:
> 
> Fixes: edd45e396829 ("PCI: dwc: designware: Move _unroll configurations to a
> separate function")
> 
> I'm not sure how to handle this case. From another side, the issue to be
> fixed is the same: call sleep in atomic context in the same driver, is it
> better to use one patch?
> 
> As for stable tree, I could send out separate patches instead. What do you
> think?

OK, I will merge the patch as-is and we will handle the stable backports
when Greg sends the patches out.

Lorenzo