From: poza@codeaurora.org
To: Thomas Tai <thomas.tai@oracle.com>
Cc: bhelgaas@google.com, keith.busch@intel.com,
linux-pci@vger.kernel.org, linux-pci-owner@vger.kernel.org
Subject: Re: [PATCH 1/1] PCI/AER: prevent pcie_do_fatal_recovery from using device after it is removed
Date: Wed, 15 Aug 2018 20:27:52 +0530 [thread overview]
Message-ID: <fa97a363892f757203ec7209f374a220@codeaurora.org> (raw)
In-Reply-To: <8b8db3c5-e884-d697-6193-b409276f9638@oracle.com>
On 2018-08-14 19:21, Thomas Tai wrote:
> On 08/14/2018 05:22 AM, poza@codeaurora.org wrote:
>> On 2018-08-14 14:46, poza@codeaurora.org wrote:
>>> On 2018-08-13 22:21, Thomas Tai wrote:
>>>> In order to prevent the pcie_do_fatal_recovery() from
>>>> using the device after it is removed, the device's
>>>> domain:bus:devfn is stored at the entry of
>>>> pcie_do_fatal_recovery(). After rescanning the bus, the
>>>> stored domain:bus:devfn is used to find the device and
>>>> uses to report pci_info. The original issue only happens
>>>> on an non-bridge device, a local variable is used instead
>>>> of checking the device's header type.
>>>>
>>>> Signed-off-by: Thomas Tai <thomas.tai@oracle.com>
>>>> ---
>>>> drivers/pci/pcie/err.c | 33 +++++++++++++++++++++++----------
>>>> 1 file changed, 23 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
>>>> index f02e334..3414445 100644
>>>> --- a/drivers/pci/pcie/err.c
>>>> +++ b/drivers/pci/pcie/err.c
>>>> @@ -287,15 +287,20 @@ void pcie_do_fatal_recovery(struct pci_dev
>>>> *dev,
>>>> u32 service)
>>>> struct pci_bus *parent;
>>>> struct pci_dev *pdev, *temp;
>>>> pci_ers_result_t result;
>>>> + bool is_bridge_device = false;
>>>> + u16 domain = pci_domain_nr(dev->bus);
>>>> + u8 bus = dev->bus->number;
>>>> + u8 devfn = dev->devfn;
>>>>
>>>> - if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
>>>> + if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
>>>> + is_bridge_device = true;
>>>> udev = dev;
>>>> - else
>>>> + } else {
>>>> udev = dev->bus->self;
>>>> + }
>>>>
>>>> parent = udev->subordinate;
>>>> pci_lock_rescan_remove();
>>>> - pci_dev_get(dev);
>>>> list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
>>>> bus_list) {
>>>> pci_dev_get(pdev);
>>>> @@ -309,27 +314,35 @@ void pcie_do_fatal_recovery(struct pci_dev
>>>> *dev,
>>>> u32 service)
>>>>
>>>> result = reset_link(udev, service);
>>>>
>>>> - if ((service == PCIE_PORT_SERVICE_AER) &&
>>>> - (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)) {
>>>> + if (service == PCIE_PORT_SERVICE_AER && is_bridge_device) {
>>>> /*
>>>> * If the error is reported by a bridge, we think this
>>>> error
>>>> * is related to the downstream link of the bridge, so we
>>>> * do error recovery on all subordinates of the bridge
>>>> instead
>>>> * of the bridge and clear the error status of the bridge.
>>>> */
>>>> - pci_cleanup_aer_uncorrect_error_status(dev);
>>>> + pci_cleanup_aer_uncorrect_error_status(udev);
>>>> }
>>>>
>>>> if (result == PCI_ERS_RESULT_RECOVERED) {
>>>> if (pcie_wait_for_link(udev, true))
>>>> pci_rescan_bus(udev->bus);
>>>> - pci_info(dev, "Device recovery from fatal error
>>>> successful\n");
>>>> + /* find the pci_dev after rescanning the bus */
>>>> + dev = pci_get_domain_bus_and_slot(domain, bus, devfn);
>>> one of the motivations was to remove and re-enumerate rather then
>>> going thorugh driver's recovery sequence
>>> was; it might be possible that hotplug capable bridge, the device
>>> might have changed.
>>> hence this check will fail
>
> Thanks Oza for your information. Instead of searching for the dev_pci,
> should I just use the stored domain:bus:devfn to printout the info?
>
>>>> + if (dev)
>>>> + pci_info(dev, "Device recovery from fatal error
>>>> successful\n");
>>>> + else
>>>> + pr_err("AER: Can not find pci_dev for
>>>> %04x:%02x:%02x.%x\n",
>>>> + domain, bus,
>>>> + PCI_SLOT(devfn), PCI_FUNC(devfn));
>>>> + pci_dev_put(dev);
>
> That is, replace above with:
>
> pr_info("AER: Device %04x:%02x:%02x.%x recover from fatal error
> successful\n", domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
>
is this not sufficient to print ? which is there already.
pci_info(dev, "Device recovery from fatal error successful\n");
>
>>>> } else {
>>>> - pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
>>>> - pci_info(dev, "Device recovery from fatal error failed\n");
>>>> + if (is_bridge_device)
>>> previously there was no condition.. why is this required now ?
>>> and it was doing on "dev" while you are doing it on "udev"
>> is that the reason we dont watnt o use dev after it is removed ?
>> instead do pci_uevent_ers on bridge ?
>
>
> Yes, that's exactly the reason. I should have written down the reason
> in the commit log. Here is the details explanation for the benefit of
> others. If the failing device is a bridge device, udev is equal to
> dev. So we can use udev in the pci_uevent_ers. But for non bridge
> device the device is already removed from the bus and thus can't send
> pci_uevent_ers.
>
> Thank you,
> Thomas
>
>>>> + pci_uevent_ers(udev, PCI_ERS_RESULT_DISCONNECT);
>>>> + pr_err("AER: Device %04x:%02x:%02x.%x recovery from fatal
>>>> error failed\n",
>>>> + domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
>>>> }
>>>>
>>>> - pci_dev_put(dev);
>>>> pci_unlock_rescan_remove();
>>>> }
>>>
>>> Regards,
>>> Oza.
next prev parent reply other threads:[~2018-08-15 17:50 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-13 16:51 [PATCH 0/1] PCI/AER: prevent pcie_do_fatal_recovery from using device after it is removed Thomas Tai
2018-08-13 16:51 ` [PATCH 1/1] " Thomas Tai
2018-08-14 9:16 ` poza
2018-08-14 9:22 ` poza
2018-08-14 13:51 ` Thomas Tai
2018-08-15 14:57 ` poza [this message]
2018-08-15 15:02 ` Thomas Tai
2018-08-15 15:26 ` poza
2018-08-15 15:43 ` Thomas Tai
2018-08-15 15:59 ` poza
2018-08-15 16:04 ` Thomas Tai
2018-08-15 21:55 ` Benjamin Herrenschmidt
2018-08-15 21:56 ` Benjamin Herrenschmidt
2018-08-16 6:36 ` poza
2018-08-16 6:51 ` Benjamin Herrenschmidt
2018-08-16 6:59 ` Benjamin Herrenschmidt
2018-08-16 8:07 ` poza
2018-08-16 8:12 ` Benjamin Herrenschmidt
2018-08-16 9:03 ` poza
2018-08-16 10:07 ` Benjamin Herrenschmidt
2018-08-16 14:11 ` poza
2018-08-16 23:30 ` Benjamin Herrenschmidt
2018-08-17 10:29 ` poza
2018-08-17 10:44 ` poza
2018-08-18 7:38 ` Benjamin Herrenschmidt
2018-08-16 7:05 ` Benjamin Herrenschmidt
2018-08-16 7:15 ` Benjamin Herrenschmidt
2018-08-16 7:56 ` poza
2018-08-16 8:10 ` Benjamin Herrenschmidt
2018-08-16 8:05 ` poza
2018-08-16 8:15 ` Benjamin Herrenschmidt
2018-08-16 8:22 ` poza
2018-08-16 8:28 ` Benjamin Herrenschmidt
2018-08-16 13:30 ` Thomas Tai
2018-08-16 13:46 ` Sinan Kaya
2018-08-16 23:27 ` Benjamin Herrenschmidt
2018-08-17 6:35 ` poza
2018-08-19 2:24 ` Bjorn Helgaas
2018-08-20 5:09 ` poza
2018-08-20 5:15 ` Benjamin Herrenschmidt
2018-08-20 13:02 ` Thomas Tai
2018-08-20 13:27 ` Benjamin Herrenschmidt
2018-08-19 2:19 ` Bjorn Helgaas
2018-08-19 21:41 ` Sinan Kaya
2018-08-20 2:03 ` Benjamin Herrenschmidt
2018-08-20 5:19 ` poza
2018-08-20 5:33 ` Benjamin Herrenschmidt
2018-08-20 7:56 ` poza
2018-08-20 11:22 ` Benjamin Herrenschmidt
2018-08-20 13:26 ` poza
2018-08-20 21:02 ` Benjamin Herrenschmidt
2018-08-21 5:14 ` poza
2018-08-21 6:06 ` Benjamin Herrenschmidt
2018-08-21 14:37 ` Keith Busch
2018-08-21 15:07 ` Sinan Kaya
2018-08-21 15:29 ` Keith Busch
2018-08-21 15:50 ` Sinan Kaya
2018-08-21 15:55 ` Sinan Kaya
2018-08-21 16:44 ` Keith Busch
2018-08-21 15:30 ` poza
2018-08-21 21:14 ` Benjamin Herrenschmidt
2018-08-21 22:04 ` Keith Busch
2018-08-21 22:33 ` Keith Busch
2018-08-21 23:06 ` Benjamin Herrenschmidt
2018-08-21 23:13 ` Keith Busch
2018-08-22 0:36 ` Benjamin Herrenschmidt
2018-08-30 0:01 ` Keith Busch
2018-08-30 0:10 ` Sinan Kaya
2018-08-30 0:46 ` Keith Busch
2018-08-30 4:26 ` Benjamin Herrenschmidt
2018-08-20 15:53 ` Keith Busch
2018-08-20 16:13 ` poza
2018-08-20 16:32 ` Keith Busch
2018-08-20 21:05 ` Benjamin Herrenschmidt
2018-08-20 21:21 ` Sinan Kaya
2018-08-20 21:35 ` Keith Busch
2018-08-20 21:53 ` Benjamin Herrenschmidt
2018-08-20 22:02 ` Sinan Kaya
2018-08-20 22:04 ` Benjamin Herrenschmidt
2018-08-20 22:13 ` Sinan Kaya
2018-08-20 22:19 ` Benjamin Herrenschmidt
2018-08-22 9:13 ` Lukas Wunner
2018-08-22 14:38 ` Keith Busch
2018-08-22 14:51 ` Sinan Kaya
2018-08-20 22:13 ` Keith Busch
2018-08-20 22:19 ` Benjamin Herrenschmidt
2018-08-21 1:30 ` Keith Busch
2018-08-20 4:37 ` Benjamin Herrenschmidt
2018-08-20 4:39 ` PATCH] Partial revert of "PCI/AER: Handle ERR_FATAL with removal and re-enumeration of devices" Benjamin Herrenschmidt
2018-08-21 19:50 ` Bjorn Helgaas
2018-08-22 4:35 ` poza
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