linux-kernel - [PATCH 0/1] Arch use of pci_dev_is

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Date:   Fri, 10 Sep 2021 16:19:39 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "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: [PATCH 0/1] Arch use of pci_dev_is_added()

Hi Bjorn, Hi Michael,

In my proposal to make pci_dev_is_added() more regularly usable by arch code
you mentioned[0] that you believe the uses in arch/powerpc are not necessary
anymore. From code reading I agree and so does Oliver O'Halloran[1].

So as promised here is a patch removing them. I only compile tested this as
I don't have access to a powerpc system.

I've also looked a bit more into our use in s390 and as dicussed previously
I don't think we can cleanly get rid of the existing one in
arch/s390/pci_sysfs.c:recover_store() because we need to distinguish an already
removed pdev just by looking at the pdev itself.

As for new uses I think in the upcoming automatic recovery code we can rely on
the fact that a removed device has pdev->driver == NULL and don't need
pci_dev_is_added() but it would make things clearer. I also noticed that before
commit 44bda4b7d26e9 ("PCI: Fix is_added/is_busmaster race condition") there
was simply a pdev->is_added flag that was cleanly accessible by arch code. So
I wanted to ask for your advice.

Thanks,
Niklas

[0] https://lore.kernel.org/lkml/20210825190444.GA3593752@bjorn-Precision-5520/
[1] https://lore.kernel.org/lkml/CAOSf1CFyuf9FaeSNparj+7W0mKTPvtcM8vxjHDSFsNDC6k_7xQ@mail.gmail.com/

Niklas Schnelle (1):
  powerpc: Drop superfluous pci_dev_is_added() calls

 arch/powerpc/platforms/powernv/pci-sriov.c | 6 ------
 arch/powerpc/platforms/pseries/setup.c     | 3 +--
 2 files changed, 1 insertion(+), 8 deletions(-)

-- 
2.25.1