linux-kernel - Re: [PATCH v4 4/8] PCI/DPC: Use pci_aer_clear_status() in dpc_process_error()

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Date:   Thu, 21 Oct 2021 22:06:11 +0530
From:   Naveen Naidu <naveennaidu479@...il.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     bhelgaas@...gle.com, ruscur@...sell.cc, oohall@...il.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH v4 4/8] PCI/DPC: Use pci_aer_clear_status() in
 dpc_process_error()

On 20/10, Bjorn Helgaas wrote:
> On Tue, Oct 05, 2021 at 10:48:11PM +0530, Naveen Naidu wrote:
> > dpc_process_error() clears both AER fatal and non fatal status
> > registers. Instead of clearing each status registers via a different
> > function call use pci_aer_clear_status().
> > 
> > This helps clean up the code a bit.
> > 
> > Signed-off-by: Naveen Naidu <naveennaidu479@...il.com>
> > ---
> >  drivers/pci/pcie/dpc.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> > index df3f3a10f8bc..faf4a1e77fab 100644
> > --- a/drivers/pci/pcie/dpc.c
> > +++ b/drivers/pci/pcie/dpc.c
> > @@ -288,8 +288,7 @@ void dpc_process_error(struct pci_dev *pdev)
> >  		 dpc_get_aer_uncorrect_severity(pdev, &info) &&
> >  		 aer_get_device_error_info(pdev, &info)) {
> >  		aer_print_error(pdev, &info);
> > -		pci_aer_clear_nonfatal_status(pdev);
> > -		pci_aer_clear_fatal_status(pdev);
> > +		pci_aer_clear_status(pdev);
> 
> The commit log suggests that this is a simple cleanup that doesn't
> change any behavior, but that's not quite true:
> 
>   - The new code would clear PCI_ERR_ROOT_STATUS, but the old code
>     does not.
> 
>   - The old code masks the status bits with the severity bits before
>     clearing, but the new code does not.
> 
> The commit log needs to show why these changes are what we want.
>

Reading through the code again, I realize how wrong(stupid) I was when
making this patch. I was thinking that:

  pci_aer_clear_status() = pci_aer_clear_fatal_status() + pci_aer_clear_nonfatal_status()

Now I understand, that it is not at all the case. I apologize for the
mistake. I'll make sure to be meticulous while reading functions and not
just assume their behaviour just from their function names.

I'll drop this patch in the next version of the patch series I make.

Apologies again ^^'

> >  	}
> >  }
> >  
> > -- 
> > 2.25.1
> > 
> > _______________________________________________
> > Linux-kernel-mentees mailing list
> > Linux-kernel-mentees@...ts.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

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