linux-kernel - Re: [PATCH v4 2/3] PCI: endpoint: Fix error handling in pci_epc_epf

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Date:   Thu, 14 Dec 2017 12:07:57 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Niklas Cassel <niklas.cassel@...s.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Niklas Cassel <niklass@...s.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] PCI: endpoint: Fix error handling in
 pci_epc_epf_link()

On Thu, Dec 14, 2017 at 04:37:22PM +0530, Kishon Vijay Abraham I wrote:
> Hi Niklas,
> 
> On Tuesday 12 December 2017 07:46 PM, Niklas Cassel wrote:
> > The error handling in pci_epc_epf_link() is broken,
> > since the clean up code for pci_epc_add_epf() calls clear_bit(),
> > even though the matching set_bit() is done after pci_epc_add_epf().
> > 
> > Also, clear_bit() should be done before pci_epc_remove_epf(),
> > since clean up code should normally do things in the reverse order.
> > 
> > Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
> > Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
> > Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> > ---
> >  drivers/pci/endpoint/pci-ep-cfs.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> > index 4f74386c1ced..e1f5adc9e113 100644
> > --- a/drivers/pci/endpoint/pci-ep-cfs.c
> > +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> > @@ -106,7 +106,7 @@ static int pci_epc_epf_link(struct config_item *epc_item,
> >  	epf = epf_group->epf;
> >  	ret = pci_epc_add_epf(epc, epf);
> >  	if (ret)
> > -		goto err_add_epf;
> > +		return ret;
> 
> Actually the func_no should be populated before invoking pci_epc_add_epf. Once
> that is done, the error handling should be fine.

Which means that current code works because pci_epc_add_epf() is called
with epf->func_no == 0 right ? I agree that the correct fix consists in
setting the epf->func_no before calling pci_epc_add_epf(), this means
that this patch and patch 3 need updating.

Thanks,
Lorenzo