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Message-ID: <29c21a3fbaeb56c0581da66b9203dfd1@codeaurora.org>
Date: Thu, 10 May 2018 19:56:00 +0530
From: poza@...eaurora.org
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Philippe Ombredanne <pombredanne@...b.com>,
Thomas Gleixner <tglx@...utronix.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Kate Stewart <kstewart@...uxfoundation.org>,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
Dongdong Liu <liudongdong3@...wei.com>,
Keith Busch <keith.busch@...el.com>, Wei Zhang <wzhang@...com>,
Sinan Kaya <okaya@...eaurora.org>,
Timur Tabi <timur@...eaurora.org>,
linux-pci-owner@...r.kernel.org
Subject: Re: [PATCH v15 8/9] PCI/DPC: Unify and plumb error handling into DPC
On 2018-05-10 18:52, Bjorn Helgaas wrote:
> On Thu, May 03, 2018 at 01:03:57AM -0400, Oza Pawandeep wrote:
>> Current DPC driver does not do recovery, e.g. calling end-point's
>> driver's
>> callbacks, which sanitize the sw.
>>
>> DPC driver implements link_reset callback, and calls
>> pci_do_recovery().
>>
>> Signed-off-by: Oza Pawandeep <poza@...eaurora.org>
>>
>> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
>> index 80ec384..aed7c9f 100644
>> --- a/drivers/pci/pcie/dpc.c
>> +++ b/drivers/pci/pcie/dpc.c
>> @@ -73,29 +73,21 @@ static void dpc_wait_link_inactive(struct dpc_dev
>> *dpc)
>> pcie_wait_for_link(pdev, false);
>> }
>>
>> -static void dpc_work(struct work_struct *work)
>> +static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
>> {
>> - struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
>> - struct pci_dev *dev, *temp, *pdev = dpc->dev->port;
>> - struct pci_bus *parent = pdev->subordinate;
>> - u16 cap = dpc->cap_pos, ctl;
>> -
>> - pci_lock_rescan_remove();
>> - list_for_each_entry_safe_reverse(dev, temp, &parent->devices,
>> - bus_list) {
>> - pci_dev_get(dev);
>> - pci_dev_set_disconnected(dev, NULL);
>> - if (pci_has_subordinate(dev))
>> - pci_walk_bus(dev->subordinate,
>> - pci_dev_set_disconnected, NULL);
>> - pci_stop_and_remove_bus_device(dev);
>> - pci_dev_put(dev);
>> - }
>> - pci_unlock_rescan_remove();
>
> I think it would be good to have a comment here about why this
> "reset_link"
> function doesn't actually reset the link, e.g.,
>
> /*
> * DPC disables the Link automatically in hardware, so it has
> * already been reset by the time we get here.
> */
>
>> + struct dpc_dev *dpc;
>> + struct pcie_device *pciedev;
>> + struct device *devdpc;
>> + u16 cap, ctl;
>> +
>> + devdpc = pcie_port_find_device(pdev, PCIE_PORT_SERVICE_DPC);
>> + pciedev = to_pcie_device(devdpc);
>> + dpc = get_service_data(pciedev);
>> + cap = dpc->cap_pos;
>
> And maybe one about waiting until the link is inactive, then clearing
> DPC
> Trigger Status to allow the port to leave DPC.
>
>> dpc_wait_link_inactive(dpc);
>> if (dpc->rp_extensions && dpc_wait_rp_inactive(dpc))
>> - return;
>> + return PCI_ERS_RESULT_DISCONNECT;
>> if (dpc->rp_extensions && dpc->rp_pio_status) {
>> pci_write_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS,
>> dpc->rp_pio_status);
>> @@ -108,6 +100,17 @@ static void dpc_work(struct work_struct *work)
>> pci_read_config_word(pdev, cap + PCI_EXP_DPC_CTL, &ctl);
>> pci_write_config_word(pdev, cap + PCI_EXP_DPC_CTL,
>> ctl | PCI_EXP_DPC_CTL_INT_EN);
>> +
>> + return PCI_ERS_RESULT_RECOVERED;
>> +}
>> +
>> +static void dpc_work(struct work_struct *work)
>> +{
>> + struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
>> + struct pci_dev *pdev = dpc->dev->port;
>> +
>> + /* From DPC point of view error is always FATAL. */
>> + pcie_do_recovery(pdev, DPC_FATAL);
>> }
>>
>> static void dpc_process_rp_pio_error(struct dpc_dev *dpc)
>> @@ -288,6 +291,7 @@ static struct pcie_port_service_driver dpcdriver =
>> {
>> .service = PCIE_PORT_SERVICE_DPC,
>> .probe = dpc_probe,
>> .remove = dpc_remove,
>> + .reset_link = dpc_reset_link,
>> };
>>
>> static int __init dpc_service_init(void)
>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
>> index 877785d..526aba8 100644
>> --- a/drivers/pci/pcie/err.c
>> +++ b/drivers/pci/pcie/err.c
>> @@ -181,11 +181,12 @@ static pci_ers_result_t
>> default_reset_link(struct pci_dev *dev)
>> return PCI_ERS_RESULT_RECOVERED;
>> }
>>
>> -static pci_ers_result_t reset_link(struct pci_dev *dev)
>> +static pci_ers_result_t reset_link(struct pci_dev *dev, int severity)
>> {
>> struct pci_dev *udev;
>> pci_ers_result_t status;
>> struct pcie_port_service_driver *driver;
>> + u32 service;
>>
>> if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
>> /* Reset this port for all subordinates */
>> @@ -196,7 +197,12 @@ static pci_ers_result_t reset_link(struct pci_dev
>> *dev)
>> }
>>
>> /* Use the aer driver of the component firstly */
>> - driver = pcie_port_find_service(udev, PCIE_PORT_SERVICE_AER);
>> + if (severity == DPC_FATAL)
>> + service = PCIE_PORT_SERVICE_DPC;
>> + else
>> + service = PCIE_PORT_SERVICE_AER;
>> +
>> + driver = pcie_port_find_service(udev, service);
>
> This is where I was wondering about passing in "service" directly
> instead
> of "severity".
I will take care of all your comments made on all the patches.
but this one I do not understand.
passing service directly instead of severity ? (I do not think you meant
to write severity there)
perhaps do you mean following ?
if (severity == DPC_FATAL)
pcie_port_find_service(udev, PCIE_PORT_SERVICE_DPC);
else
pcie_port_find_service(udev, PCIE_PORT_SERVICE_AER);
>
>> if (driver && driver->reset_link) {
>> status = driver->reset_link(udev);
>> @@ -302,7 +308,7 @@ static pci_ers_result_t do_fatal_recovery(struct
>> pci_dev *dev, int severity)
>> pci_dev_put(pdev);
>> }
>>
>> - result = reset_link(udev);
>> + result = reset_link(udev, severity);
>> if (result == PCI_ERS_RESULT_RECOVERED)
>> if (pcie_wait_for_link(udev, true))
>> pci_rescan_bus(udev->bus);
>> @@ -326,7 +332,8 @@ void pcie_do_recovery(struct pci_dev *dev, int
>> severity)
>> pci_ers_result_t status;
>> enum pci_channel_state state;
>>
>> - if (severity == AER_FATAL) {
>> + if ((severity == AER_FATAL) ||
>> + (severity == DPC_FATAL)) {
>> status = do_fatal_recovery(dev, severity);
>> if (status != PCI_ERS_RESULT_RECOVERED)
>> goto failed;
>> diff --git a/include/linux/aer.h b/include/linux/aer.h
>> index 8f87bbe..0c506fe 100644
>> --- a/include/linux/aer.h
>> +++ b/include/linux/aer.h
>> @@ -14,6 +14,7 @@
>> #define AER_NONFATAL 0
>> #define AER_FATAL 1
>> #define AER_CORRECTABLE 2
>> +#define DPC_FATAL 4
>>
>> struct pci_dev;
>>
>> --
>> 2.7.4
>>
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