linux-kernel - Re: [PATCH 2/2] PCI: endpoint: Use link_up() callback in place of LINK

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Message-ID: <20220831082025.GC5076@thinkpad>
Date:   Wed, 31 Aug 2022 13:50:25 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     lpieralisi@...nel.org, bhelgaas@...gle.com, kw@...ux.com,
        robh@...nel.org, vidyas@...dia.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] PCI: endpoint: Use link_up() callback in place of
 LINK_UP notifier

On Thu, Aug 25, 2022 at 03:47:10PM +0530, Kishon Vijay Abraham I wrote:
> Hi Mani,
> 
> On 11/08/22 15:12, Manivannan Sadhasivam wrote:
> > As a part of the transition towards callback mechanism for signalling the
> > events from EPC to EPF, let's use the link_up() callback in the place of
> > the LINK_UP notifier. This also removes the notifier support completely
> > from the PCI endpoint framework.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >  drivers/pci/endpoint/functions/pci-epf-test.c | 33 ++++++-------------
> >  drivers/pci/endpoint/pci-epc-core.c           |  8 +++--
> >  include/linux/pci-epc.h                       |  8 -----
> >  include/linux/pci-epf.h                       |  8 ++---
> >  4 files changed, 18 insertions(+), 39 deletions(-)
> > 
> 
> .
> .
> <snip>
> .
> .
> > diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> > index 805f3d64f93b..a51ba9f158c3 100644
> > --- a/drivers/pci/endpoint/pci-epc-core.c
> > +++ b/drivers/pci/endpoint/pci-epc-core.c
> > @@ -690,10 +690,15 @@ EXPORT_SYMBOL_GPL(pci_epc_remove_epf);
> >   */
> >  void pci_epc_linkup(struct pci_epc *epc)
> >  {
> > +	struct pci_epf *epf;
> > +
> >  	if (!epc || IS_ERR(epc))
> >  		return;
> >  
> > -	atomic_notifier_call_chain(&epc->notifier, LINK_UP, NULL);
> > +	list_for_each_entry(epf, &epc->pci_epf, list) {
> > +		if (epf->event_ops->link_up)
> > +			epf->event_ops->link_up(epf);
> > +	}
> 
> how do you ensure there is no race while invoking the call back
> functions during add/remove of epf?
> 

Good catch! These should be guarded by epf->lock.

Thanks,
Mani

> Thanks,
> Kishon

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