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Message-ID: <20180510132222.GE173327@bhelgaas-glaptop.roam.corp.google.com>
Date: Thu, 10 May 2018 08:22:22 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Oza Pawandeep <poza@...eaurora.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>
Subject: Re: [PATCH v15 8/9] PCI/DPC: Unify and plumb error handling into DPC
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".
> 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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