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From: Niklas Schnelle <schnelle@linux.ibm.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Oliver O'Halloran" <oohall@gmail.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-arch@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 0/1] Arch use of pci_dev_is_added()
Date: Fri, 10 Sep 2021 16:19:39 +0200	[thread overview]
Message-ID: <20210910141940.2598035-1-schnelle@linux.ibm.com> (raw)

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


             reply	other threads:[~2021-09-10 14:19 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-10 14:19 Niklas Schnelle [this message]
2021-09-10 14:19 ` [PATCH 1/1] powerpc: Drop superfluous pci_dev_is_added() calls Niklas Schnelle
2021-09-11 11:09   ` Michael Ellerman
2021-09-13 14:58     ` Oliver O'Halloran
2021-09-14 19:31   ` Bjorn Helgaas
2021-09-15  0:23     ` Michael Ellerman
2021-10-11 12:06 ` [PATCH 0/1] Arch use of pci_dev_is_added() Michael Ellerman

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