linux-kernel - Re: [PATCH v11 2/7] PCI/AER: factor out error reporting from AER

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Date:   Mon, 26 Feb 2018 14:23:21 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     poza@...eaurora.org
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dongdong Liu <liudongdong3@...wei.com>,
        Keith Busch <keith.busch@...el.com>, Wei Zhang <wzhang@...com>,
        Sinan Kaya <okaya@...eaurora.org>,
        Timur Tabi <timur@...eaurora.org>
Subject: Re: [PATCH v11 2/7] PCI/AER: factor out error reporting from AER

On Mon, Feb 26, 2018 at 11:02:50AM +0530, poza@...eaurora.org wrote:
> On 2018-02-24 05:12, Bjorn Helgaas wrote:
> > On Fri, Feb 23, 2018 at 01:53:59PM +0530, Oza Pawandeep wrote:

> > >   * handle_error_source - handle logging error into an event log
> > > diff --git a/drivers/pci/pcie/pcie-err.c b/drivers/pci/pcie/pcie-err.c
> > > new file mode 100644
> > > index 0000000..fcd5add
> > > --- /dev/null
> > > +++ b/drivers/pci/pcie/pcie-err.c
> > > @@ -0,0 +1,334 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * This file implements the error recovery as a core part of PCIe
> > > error reporting.
> > > + * When a PCIe error is delivered, an error message will be
> > > collected and printed
> > > + * to console, then, an error recovery procedure will be executed
> > > by following
> > > + * the PCI error recovery rules.
> > 
> > Wrap this so it fits in 80 columns.
> 
> I thought of keeping the way it was before (hence did not change it)
> I would change it now.

The original text fit in 80 columns, but you changed the text a little
bit as part of making this code more generic, which made it not fit
anymore.  Ideally I would leave the text the same in this patch that
only moves code, then update the text (and rewrap it) in the patch
that makes the code more generic.

> > > +static pci_ers_result_t reset_link(struct pci_dev *dev)
> > > +{
> > > +	struct pci_dev *udev;
> > > +	pci_ers_result_t status;
> > > +	struct pcie_port_service_driver *driver = NULL;
> > > +
> > > +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> > > +		/* Reset this port for all subordinates */
> > > +		udev = dev;
> > > +	} else {
> > > +		/* Reset the upstream component (likely downstream port) */
> > > +		udev = dev->bus->self;
> > > +	}
> > > +
> > > +#if IS_ENABLED(CONFIG_PCIEAER)
> > 
> > AER can't be a module, so you can use just:
> > 
> >   #ifdef CONFIG_PCIEAER
> > 
> > This ifdef should be added in the patch where you add a caller from
> > non-AER
> > code.  This patch should only move code, not change it.
> 
> ok, it can remain unchanged. but reset_link() is called by
> pcie_do_recovery()
> and pcie_do_recovery can be called by various agents such as AER, DPC.
> so let us say if DPC calls pcie_do_recovery, then DPC has no way of knowing
> that AER is enabled or not.
> in fact it should not know, but err.c/reset_link() should take care somehow.

If all you're doing is moving code, the functionality isn't changing
and you shouldn't need to add the ifdef.  At the point where you add a
new caller and the #ifdef becomes necessary, you can add it there.
Then it will make sense because we can connect the ifdef with the need
for it.

> I can make it a separate patch to do #ifdef CONFIG_PCIEAER inside
> reset_link()
> or
> I can add severity parameter in reset_link() so based on severity it can
> find the service.
> 
> but I think you have comment to unify the find_aer_service and
> find_dpc_service into a pcie_find_service (routine)
> so I will see how I can club and take care of this comment. [without the
> need of #ifdef]