linux-kernel - Re: [PATCH 1/1] powerpc: Drop superfluous pci_dev_is

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Message-ID: <87wnnnl67a.fsf@mpe.ellerman.id.au>
Date:   Sat, 11 Sep 2021 21:09:13 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Oliver O'Halloran <oohall@...il.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-arch@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 1/1] powerpc: Drop superfluous pci_dev_is_added() calls

Niklas Schnelle <schnelle@...ux.ibm.com> writes:
> On powerpc, pci_dev_is_added() is called as part of SR-IOV fixups
> that are done under pcibios_add_device() which in turn is only called in
> pci_device_add() whih is called when a PCI device is scanned.

Thanks for cleaning this up for us.

> Now pci_dev_assign_added() is called in pci_bus_add_device() which is
> only called after scanning the device. Thus pci_dev_is_added() is always
> false and can be dropped.

My only query is whether we can pin down when that changed.

Oliver said:

  The use of pci_dev_is_added() in arch/powerpc was because in the past
  pci_bus_add_device() could be called before pci_device_add(). That was
  fixed a while ago so It should be safe to remove those calls now.

I trawled back through the history a bit but I can't remember/find which
commit changed that, Oliver can you remember?

cheers

> diff --git a/arch/powerpc/platforms/powernv/pci-sriov.c b/arch/powerpc/platforms/powernv/pci-sriov.c
> index 28aac933a439..deddbb233fde 100644
> --- a/arch/powerpc/platforms/powernv/pci-sriov.c
> +++ b/arch/powerpc/platforms/powernv/pci-sriov.c
> @@ -9,9 +9,6 @@
>  
>  #include "pci.h"
>  
> -/* for pci_dev_is_added() */
> -#include "../../../../drivers/pci/pci.h"
> -
>  /*
>   * The majority of the complexity in supporting SR-IOV on PowerNV comes from
>   * the need to put the MMIO space for each VF into a separate PE. Internally
> @@ -228,9 +225,6 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
>  
>  void pnv_pci_ioda_fixup_iov(struct pci_dev *pdev)
>  {
> -	if (WARN_ON(pci_dev_is_added(pdev)))
> -		return;
> -
>  	if (pdev->is_virtfn) {
>  		struct pnv_ioda_pe *pe = pnv_ioda_get_pe(pdev);
>  
> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
> index f79126f16258..2188054470c1 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -74,7 +74,6 @@
>  #include <asm/hvconsole.h>
>  
>  #include "pseries.h"
> -#include "../../../../drivers/pci/pci.h"
>  
>  DEFINE_STATIC_KEY_FALSE(shared_processor);
>  EXPORT_SYMBOL(shared_processor);
> @@ -750,7 +749,7 @@ static void pseries_pci_fixup_iov_resources(struct pci_dev *pdev)
>  	const int *indexes;
>  	struct device_node *dn = pci_device_to_OF_node(pdev);
>  
> -	if (!pdev->is_physfn || pci_dev_is_added(pdev))
> +	if (!pdev->is_physfn)
>  		return;
>  	/*Firmware must support open sriov otherwise dont configure*/
>  	indexes = of_get_property(dn, "ibm,open-sriov-vf-bar-info", NULL);
> -- 
> 2.25.1