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From: "Oliver O'Halloran" <oohall@gmail.com>
To: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Linas Vepstas <linasvepstas@gmail.com>,
	Russell Currey <ruscur@russell.cc>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-s390@vger.kernel.org,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Pierre Morel <pmorel@linux.ibm.com>
Subject: Re: [PATCH 0/5] s390/pci: automatic error recovery
Date: Tue, 7 Sep 2021 12:04:35 +1000	[thread overview]
Message-ID: <CAOSf1CFyuf9FaeSNparj+7W0mKTPvtcM8vxjHDSFsNDC6k_7xQ@mail.gmail.com> (raw)
In-Reply-To: <20210906094927.524106-1-schnelle@linux.ibm.com>

On Mon, Sep 6, 2021 at 7:49 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
>
> Patch 3 I already sent separately resulting in the discussion below but without
> a final conclusion.
>
> https://lore.kernel.org/lkml/20210720150145.640727-1-schnelle@linux.ibm.com/
>
> I believe even though there were some doubts about the use of
> pci_dev_is_added() by arch code the existing uses as well as the use in the
> final patch of this series warrant this export.

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.

> Patch 4 "PCI: Export pci_dev_lock()" is basically an extension to commit
> e3a9b1212b9d ("PCI: Export pci_dev_trylock() and pci_dev_unlock()") which
> already exported pci_dev_trylock(). In the final patch we make use of
> pci_dev_lock() to wait for any other exclusive uses of the pdev to be finished
> before starting recovery.

Hmm, I noticed the EEH
(arch/powerpc/kernel/eeh_driver.c:eeh_pe_report_edev())  and the
generic PCIe error recovery code (see
drivers/pci/pcie/err.c:report_error_detected()) only call
device_lock() before entering the driver's error handling callbacks. I
wonder if they should be using pci_dev_lock() instead. The only real
difference is that pci_dev_lock() will also block user space from
accessing the device's config space while error recovery is in
progress which seems sensible enough.

  parent reply	other threads:[~2021-09-07  2:04 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06  9:49 [PATCH 0/5] s390/pci: automatic error recovery Niklas Schnelle
2021-09-06  9:49 ` [PATCH 1/5] s390/pci: refresh function handle in iomap Niklas Schnelle
2021-09-06  9:49 ` [PATCH 2/5] s390/pci: implement reset_slot for hotplug slot Niklas Schnelle
2021-09-06  9:49 ` [PATCH 3/5] PCI: Move pci_dev_is/assign_added() to pci.h Niklas Schnelle
2021-09-07  0:22   ` kernel test robot
2021-09-07  0:25   ` kernel test robot
2021-09-07  7:51     ` Andy Shevchenko
2021-09-07  8:14       ` Niklas Schnelle
2021-09-06  9:49 ` [PATCH 4/5] PCI: Export pci_dev_lock() Niklas Schnelle
2021-09-06  9:49 ` [PATCH 5/5] s390/pci: implement minimal PCI error recovery Niklas Schnelle
2021-09-07  2:04 ` Oliver O'Halloran [this message]
2021-09-07  8:45   ` [PATCH 0/5] s390/pci: automatic " Niklas Schnelle
2021-09-07 12:21     ` Niklas Schnelle
2021-09-08  1:37       ` Oliver O'Halloran
2021-09-08  8:09         ` Niklas Schnelle
     [not found] ` <CAHrUA34TK6U4TB34FHejott9TdFvSgAedOpmro-Uj2ZwnvzecQ@mail.gmail.com>
2021-09-07  2:10   ` Fwd: " Linas Vepstas
2021-09-07  7:49   ` Niklas Schnelle

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