From: "Oliver O'Halloran" <oohall@gmail.com>
To: Frederic Barrat <fbarrat@linux.ibm.com>
Cc: Christophe Lombard <clombard@linux.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Alastair D'Silva <alastair@au1.ibm.com>,
Andrew Donnellan <andrew.donnellan@au1.ibm.com>,
Greg Kurz <groug@kaod.org>
Subject: Re: [PATCH 02/11] powerpc/powernv/ioda: Protect PE list
Date: Wed, 20 Nov 2019 00:22:18 +1100 [thread overview]
Message-ID: <CAOSf1CHstMRhC9dqsuvZnQuRyLwMrQkcuMYFDobq59KvYG1hEQ@mail.gmail.com> (raw)
In-Reply-To: <882c0d26-7931-a2e9-c99a-7732d32a6a2f@linux.ibm.com>
On Tue, Nov 19, 2019 at 11:57 PM Frederic Barrat <fbarrat@linux.ibm.com> wrote:
>
> > Do the other accessors of ioda.pe_list also need mutex protection?
> > pnv_ioda_setup_bus_PE()
> > pnv_pci_dma_bus_setup()
> > pnv_pci_init_ioda_phb()
> > pnv_pci_ioda_setup_PEs()
>
>
> I think we could also use it there, it wouldn't hurt. Those functions
> are called when the kernel is building part of the PCI topology, and
> devices are not really active yet, so I don't think it's absolutely
> required.
>
> I'm actually not sure my patch is needed either. With hotplug, the
> devices can come and go, whereas the PHB remains. So it feels right to
> start protecting the list when adding/removing a device. But I don't
> think we can really have concurrency and have 2 different operations
> adding/removing devices at the same time under the same PHB, at least
> for opencapi. Maybe for PCI, if we have multiple slots under the same
> PHB. Not sure.
Creation of new pci_dev's is serialised by the global pci rescan and
remove lock so on the creation side it's not an issue. However, we can
release IODA PEs in the pci_dev's release function which might be
called without that lock held. It's pretty hard to hit that case
though since it require something to be holding a ref to the pci_dev
even after the driver's ->remove() function has been called.
next prev parent reply other threads:[~2019-11-19 13:25 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 15:45 [PATCH 00/11] opencapi: enable card reset and link retraining Frederic Barrat
2019-09-09 15:45 ` [PATCH 01/11] powerpc/powernv/ioda: Fix ref count for devices with their own PE Frederic Barrat
2019-09-10 0:20 ` Alastair D'Silva
2019-09-26 16:44 ` Andrew Donnellan
2019-09-26 17:15 ` Frederic Barrat
2019-09-27 6:54 ` Alexey Kardashevskiy
2019-11-12 17:38 ` Frederic Barrat
2019-11-18 1:04 ` Alistair Popple
2019-11-18 1:24 ` Oliver O'Halloran
2019-11-18 2:36 ` Alistair Popple
2019-11-18 18:21 ` Frederic Barrat
2019-09-09 15:45 ` [PATCH 02/11] powerpc/powernv/ioda: Protect PE list Frederic Barrat
2019-09-10 0:34 ` Alastair D'Silva
2019-11-19 12:55 ` Frederic Barrat
2019-11-19 13:22 ` Oliver O'Halloran [this message]
2019-11-19 14:36 ` Frederic Barrat
2019-11-19 5:55 ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 03/11] powerpc/powernv/ioda: set up PE on opencapi device when enabling Frederic Barrat
2019-09-10 0:38 ` Alastair D'Silva
2019-09-27 16:43 ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 04/11] powerpc/powernv/ioda: Release opencapi device Frederic Barrat
2019-09-10 0:56 ` Alastair D'Silva
2019-11-19 17:32 ` Frederic Barrat
2019-11-19 7:08 ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 05/11] powerpc/powernv/ioda: Find opencapi slot for a device node Frederic Barrat
2019-09-10 0:57 ` Alastair D'Silva
2019-11-19 1:26 ` Andrew Donnellan
2019-11-19 14:33 ` Frederic Barrat
2019-09-09 15:45 ` [PATCH 06/11] pci/hotplug/pnv-php: Remove erroneous warning Frederic Barrat
2019-09-10 0:58 ` Alastair D'Silva
2019-11-19 5:00 ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 07/11] pci/hotplug/pnv-php: Improve error msg on power state change failure Frederic Barrat
2019-09-10 0:59 ` Alastair D'Silva
2019-11-19 2:23 ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 08/11] pci/hotplug/pnv-php: Register opencapi slots Frederic Barrat
2019-09-10 1:00 ` Alastair D'Silva
2019-11-19 5:18 ` Andrew Donnellan
2019-11-19 15:15 ` Frederic Barrat
2019-09-09 15:45 ` [PATCH 09/11] pci/hotplug/pnv-php: Relax check when disabling slot Frederic Barrat
2019-09-10 1:00 ` Alastair D'Silva
2019-09-27 15:56 ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 10/11] pci/hotplug/pnv-php: Wrap warnings in macro Frederic Barrat
2019-09-10 1:03 ` Alastair D'Silva
2019-09-26 17:18 ` Andrew Donnellan
2019-09-09 15:46 ` [PATCH 11/11] ocxl: Add PCI hotplug dependency to Kconfig Frederic Barrat
2019-09-10 1:03 ` Alastair D'Silva
2019-09-26 17:11 ` Andrew Donnellan
2019-09-24 4:24 ` [PATCH 00/11] opencapi: enable card reset and link retraining Alexey Kardashevskiy
2019-09-24 6:39 ` Frederic Barrat
2019-09-25 0:20 ` Alexey Kardashevskiy
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