Date:   Fri, 04 May 2018 12:18:03 +0530
From:   poza@...eaurora.org
To:     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 5/9] PCI/AER: Factor out error reporting from AER

On 2018-05-03 10:33, Oza Pawandeep wrote:
> This patch factors out error reporting callbacks, which are currently
> tightly coupled with AER.
> 
> DPC should be able to register callbacks and attempt recovery when DPC
> trigger event occurs.
> 
> Signed-off-by: Oza Pawandeep <poza@...eaurora.org>
> 
> diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
> index 800e1d4..03f4e0b 100644
> --- a/drivers/pci/pcie/Makefile
> +++ b/drivers/pci/pcie/Makefile
> @@ -2,7 +2,7 @@
>  #
>  # Makefile for PCI Express features and port driver
> 
> -pcieportdrv-y			:= portdrv_core.o portdrv_pci.o
> +pcieportdrv-y			:= portdrv_core.o portdrv_pci.o err.o
> 
>  obj-$(CONFIG_PCIEPORTBUS)	+= pcieportdrv.o
> 
> diff --git a/drivers/pci/pcie/aer/aerdrv.h 
> b/drivers/pci/pcie/aer/aerdrv.h
> index 08b4584..b4c9506 100644
> --- a/drivers/pci/pcie/aer/aerdrv.h
> +++ b/drivers/pci/pcie/aer/aerdrv.h
> @@ -76,36 +76,6 @@ struct aer_rpc {
>  					 */
>  };
> 
> -struct aer_broadcast_data {
> -	enum pci_channel_state state;
> -	enum pci_ers_result result;
> -};
> -
> -static inline pci_ers_result_t merge_result(enum pci_ers_result orig,
> -		enum pci_ers_result new)
> -{
> -	if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
> -		return PCI_ERS_RESULT_NO_AER_DRIVER;
> -
> -	if (new == PCI_ERS_RESULT_NONE)
> -		return orig;
> -
> -	switch (orig) {
> -	case PCI_ERS_RESULT_CAN_RECOVER:
> -	case PCI_ERS_RESULT_RECOVERED:
> -		orig = new;
> -		break;
> -	case PCI_ERS_RESULT_DISCONNECT:
> -		if (new == PCI_ERS_RESULT_NEED_RESET)
> -			orig = PCI_ERS_RESULT_NEED_RESET;
> -		break;
> -	default:
> -		break;
> -	}
> -
> -	return orig;
> -}
> -
>  extern struct bus_type pcie_port_bus_type;
>  void aer_isr(struct work_struct *work);
>  void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c
> b/drivers/pci/pcie/aer/aerdrv_core.c
> index be4ee3b..51515d1 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -228,191 +228,6 @@ static bool find_source_device(struct pci_dev 
> *parent,
>  	return true;
>  }
> 
> -static int report_error_detected(struct pci_dev *dev, void *data)
> -{
> -	pci_ers_result_t vote;
> -	const struct pci_error_handlers *err_handler;
> -	struct aer_broadcast_data *result_data;
> -	result_data = (struct aer_broadcast_data *) data;
> -
> -	device_lock(&dev->dev);
> -	dev->error_state = result_data->state;
> -
> -	if (!dev->driver ||
> -		!dev->driver->err_handler ||
> -		!dev->driver->err_handler->error_detected) {
> -		if (result_data->state == pci_channel_io_frozen &&
> -			dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
> -			/*
> -			 * In case of fatal recovery, if one of down-
> -			 * stream device has no driver. We might be
> -			 * unable to recover because a later insmod
> -			 * of a driver for this device is unaware of
> -			 * its hw state.
> -			 */
> -			pci_printk(KERN_DEBUG, dev, "device has %s\n",
> -				   dev->driver ?
> -				   "no AER-aware driver" : "no driver");
> -		}
> -
> -		/*
> -		 * If there's any device in the subtree that does not
> -		 * have an error_detected callback, returning
> -		 * PCI_ERS_RESULT_NO_AER_DRIVER prevents calling of
> -		 * the subsequent mmio_enabled/slot_reset/resume
> -		 * callbacks of "any" device in the subtree. All the
> -		 * devices in the subtree are left in the error state
> -		 * without recovery.
> -		 */
> -
> -		if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
> -			vote = PCI_ERS_RESULT_NO_AER_DRIVER;
> -		else
> -			vote = PCI_ERS_RESULT_NONE;
> -	} else {
> -		err_handler = dev->driver->err_handler;
> -		vote = err_handler->error_detected(dev, result_data->state);
> -		pci_uevent_ers(dev, PCI_ERS_RESULT_NONE);
> -	}
> -
> -	result_data->result = merge_result(result_data->result, vote);
> -	device_unlock(&dev->dev);
> -	return 0;
> -}
> -
> -static int report_mmio_enabled(struct pci_dev *dev, void *data)
> -{
> -	pci_ers_result_t vote;
> -	const struct pci_error_handlers *err_handler;
> -	struct aer_broadcast_data *result_data;
> -	result_data = (struct aer_broadcast_data *) data;
> -
> -	device_lock(&dev->dev);
> -	if (!dev->driver ||
> -		!dev->driver->err_handler ||
> -		!dev->driver->err_handler->mmio_enabled)
> -		goto out;
> -
> -	err_handler = dev->driver->err_handler;
> -	vote = err_handler->mmio_enabled(dev);
> -	result_data->result = merge_result(result_data->result, vote);
> -out:
> -	device_unlock(&dev->dev);
> -	return 0;
> -}
> -
> -static int report_slot_reset(struct pci_dev *dev, void *data)
> -{
> -	pci_ers_result_t vote;
> -	const struct pci_error_handlers *err_handler;
> -	struct aer_broadcast_data *result_data;
> -	result_data = (struct aer_broadcast_data *) data;
> -
> -	device_lock(&dev->dev);
> -	if (!dev->driver ||
> -		!dev->driver->err_handler ||
> -		!dev->driver->err_handler->slot_reset)
> -		goto out;
> -
> -	err_handler = dev->driver->err_handler;
> -	vote = err_handler->slot_reset(dev);
> -	result_data->result = merge_result(result_data->result, vote);
> -out:
> -	device_unlock(&dev->dev);
> -	return 0;
> -}
> -
> -static int report_resume(struct pci_dev *dev, void *data)
> -{
> -	const struct pci_error_handlers *err_handler;
> -
> -	device_lock(&dev->dev);
> -	dev->error_state = pci_channel_io_normal;
> -
> -	if (!dev->driver ||
> -		!dev->driver->err_handler ||
> -		!dev->driver->err_handler->resume)
> -		goto out;
> -
> -	err_handler = dev->driver->err_handler;
> -	err_handler->resume(dev);
> -	pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED);
> -out:
> -	device_unlock(&dev->dev);
> -	return 0;
> -}
> -
> -/**
> - * broadcast_error_message - handle message broadcast to downstream 
> drivers
> - * @dev: pointer to from where in a hierarchy message is broadcasted 
> down
> - * @state: error state
> - * @error_mesg: message to print
> - * @cb: callback to be broadcasted
> - *
> - * Invoked during error recovery process. Once being invoked, the 
> content
> - * of error severity will be broadcasted to all downstream drivers in 
> a
> - * hierarchy in question.
> - */
> -static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
> -	enum pci_channel_state state,
> -	char *error_mesg,
> -	int (*cb)(struct pci_dev *, void *))
> -{
> -	struct aer_broadcast_data result_data;
> -
> -	pci_printk(KERN_DEBUG, dev, "broadcast %s message\n", error_mesg);
> -	result_data.state = state;
> -	if (cb == report_error_detected)
> -		result_data.result = PCI_ERS_RESULT_CAN_RECOVER;
> -	else
> -		result_data.result = PCI_ERS_RESULT_RECOVERED;
> -
> -	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> -		/*
> -		 * 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.
> -		 */
> -		if (cb == report_error_detected)
> -			dev->error_state = state;
> -		pci_walk_bus(dev->subordinate, cb, &result_data);
> -		if (cb == report_resume) {
> -			pci_cleanup_aer_uncorrect_error_status(dev);
> -			dev->error_state = pci_channel_io_normal;
> -		}
> -	} else {
> -		/*
> -		 * If the error is reported by an end point, we think this
> -		 * error is related to the upstream link of the end point.
> -		 */
> -		if (state == pci_channel_io_normal)
> -			/*
> -			 * the error is non fatal so the bus is ok, just invoke
> -			 * the callback for the function that logged the error.
> -			 */
> -			cb(dev, &result_data);
> -		else
> -			pci_walk_bus(dev->bus, cb, &result_data);
> -	}
> -
> -	return result_data.result;
> -}
> -
> -/**
> - * default_reset_link - default reset function
> - * @dev: pointer to pci_dev data structure
> - *
> - * Invoked when performing link reset on a Downstream Port or a
> - * Root Port with no aer driver.
> - */
> -static pci_ers_result_t default_reset_link(struct pci_dev *dev)
> -{
> -	pci_reset_bridge_secondary_bus(dev);
> -	pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
> -	return PCI_ERS_RESULT_RECOVERED;
> -}
> -
>  static int find_aer_service_iter(struct device *device, void *data)
>  {
>  	struct pcie_port_service_driver *service_driver, **drv;
> @@ -430,7 +245,7 @@ static int find_aer_service_iter(struct device
> *device, void *data)
>  	return 0;
>  }
> 
> -static struct pcie_port_service_driver *find_aer_service(struct 
> pci_dev *dev)
> +struct pcie_port_service_driver *find_aer_service(struct pci_dev *dev)
>  {
>  	struct pcie_port_service_driver *drv = NULL;
> 
> @@ -439,143 +254,6 @@ static struct pcie_port_service_driver
> *find_aer_service(struct pci_dev *dev)
>  	return drv;
>  }
> 
> -static pci_ers_result_t reset_link(struct pci_dev *dev)
> -{
> -	struct pci_dev *udev;
> -	pci_ers_result_t status;
> -	struct pcie_port_service_driver *driver;
> -
> -	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> -		/* Reset this port for all subordinates */
> -		udev = dev;
> -	} else {
> -		/* Reset the upstream component (likely downstream port) */
> -		udev = dev->bus->self;
> -	}
> -
> -	/* Use the aer driver of the component firstly */
> -	driver = find_aer_service(udev);
> -
> -	if (driver && driver->reset_link) {
> -		status = driver->reset_link(udev);
> -	} else if (udev->has_secondary_link) {
> -		status = default_reset_link(udev);
> -	} else {
> -		pci_printk(KERN_DEBUG, dev, "no link-reset support at upstream 
> device %s\n",
> -			pci_name(udev));
> -		return PCI_ERS_RESULT_DISCONNECT;
> -	}
> -
> -	if (status != PCI_ERS_RESULT_RECOVERED) {
> -		pci_printk(KERN_DEBUG, dev, "link reset at upstream device %s 
> failed\n",
> -			pci_name(udev));
> -		return PCI_ERS_RESULT_DISCONNECT;
> -	}
> -
> -	return status;
> -}
> -
> -static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
> int severity)
> -{
> -	struct pci_dev *udev;
> -	struct pci_bus *parent;
> -	struct pci_dev *pdev, *temp;
> -	pci_ers_result_t result = PCI_ERS_RESULT_RECOVERED;
> -
> -	if (severity == AER_FATAL)
> -		pci_cleanup_aer_uncorrect_error_status(dev);
> -
> -	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
> -		udev = dev;
> -	else
> -		udev = dev->bus->self;
> -
> -	parent = udev->subordinate;
> -	pci_lock_rescan_remove();
> -	list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
> -				 bus_list) {
> -		pci_dev_get(pdev);
> -		pci_dev_set_disconnected(pdev, NULL);
> -		if (pci_has_subordinate(pdev))
> -			pci_walk_bus(pdev->subordinate,
> -				     pci_dev_set_disconnected, NULL);
> -		pci_stop_and_remove_bus_device(pdev);
> -		pci_dev_put(pdev);
> -	}
> -
> -	result = reset_link(udev);
> -	if (result == PCI_ERS_RESULT_RECOVERED)
> -		if (pcie_wait_for_link(udev, true))
> -			pci_rescan_bus(udev->bus);
> -
> -	pci_unlock_rescan_remove();
> -
> -	return result;
> -}
> -
> -/**
> - * pcie_do_recovery - handle nonfatal/fatal error recovery process
> - * @dev: pointer to a pci_dev data structure of agent detecting an 
> error
> - * @severity: error severity type
> - *
> - * Invoked when an error is nonfatal/fatal. Once being invoked, 
> broadcast
> - * error detected message to all downstream drivers within a hierarchy 
> in
> - * question and return the returned code.
> - */
> -void pcie_do_recovery(struct pci_dev *dev, int severity)
> -{
> -	pci_ers_result_t status;
> -	enum pci_channel_state state;
> -
> -	if (severity == AER_FATAL) {
> -		status = pcie_do_fatal_recovery(dev, severity);
> -		if (status != PCI_ERS_RESULT_RECOVERED)
> -			goto failed;
> -		return;
> -	}
> -	else
> -		state = pci_channel_io_normal;
> -
> -	status = broadcast_error_message(dev,
> -			state,
> -			"error_detected",
> -			report_error_detected);
> -
> -	if (status == PCI_ERS_RESULT_CAN_RECOVER)
> -		status = broadcast_error_message(dev,
> -				state,
> -				"mmio_enabled",
> -				report_mmio_enabled);
> -
> -	if (status == PCI_ERS_RESULT_NEED_RESET) {
> -		/*
> -		 * TODO: Should call platform-specific
> -		 * functions to reset slot before calling
> -		 * drivers' slot_reset callbacks?
> -		 */
> -		status = broadcast_error_message(dev,
> -				state,
> -				"slot_reset",
> -				report_slot_reset);
> -	}
> -
> -	if (status != PCI_ERS_RESULT_RECOVERED)
> -		goto failed;
> -
> -	broadcast_error_message(dev,
> -				state,
> -				"resume",
> -				report_resume);
> -
> -	pci_info(dev, "AER: Device recovery successful\n");
> -	return;
> -
> -failed:
> -	pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
> -	/* TODO: Should kernel panic here? */
> -	pci_info(dev, "AER: Device recovery failed\n");
> -}
> -
>  /**
>   * handle_error_source - handle logging error into an event log
>   * @aerdev: pointer to pcie_device data structure of the root port
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> new file mode 100644
> index 0000000..55df974
> --- /dev/null
> +++ b/drivers/pci/pcie/err.c
> @@ -0,0 +1,377 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * This file implements the error recovery as a core part of PCIe 
> error
> + * reporting. When a PCIe error is delivered, an error message will be
> + * collected and printed to console, then, an error recovery procedure
> + * will be executed by following the PCI error recovery rules.
> + *
> + * Copyright (C) 2006 Intel Corp.
> + *	Tom Long Nguyen (tom.l.nguyen@...el.com)
> + *	Zhang Yanmin (yanmin.zhang@...el.com)
> + *
> + */
> +
> +#include <linux/pci.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/aer.h>
> +#include "portdrv.h"
> +#include "../pci.h"
> +
> +struct aer_broadcast_data {
> +	enum pci_channel_state state;
> +	enum pci_ers_result result;
> +};
> +
> +static pci_ers_result_t merge_result(enum pci_ers_result orig,
> +				  enum pci_ers_result new)
> +{
> +	if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
> +		return PCI_ERS_RESULT_NO_AER_DRIVER;
> +
> +	if (new == PCI_ERS_RESULT_NONE)
> +		return orig;
> +
> +	switch (orig) {
> +	case PCI_ERS_RESULT_CAN_RECOVER:
> +	case PCI_ERS_RESULT_RECOVERED:
> +		orig = new;
> +		break;
> +	case PCI_ERS_RESULT_DISCONNECT:
> +		if (new == PCI_ERS_RESULT_NEED_RESET)
> +			orig = PCI_ERS_RESULT_NEED_RESET;
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return orig;
> +}
> +
> +static int report_error_detected(struct pci_dev *dev, void *data)
> +{
> +	pci_ers_result_t vote;
> +	const struct pci_error_handlers *err_handler;
> +	struct aer_broadcast_data *result_data;
> +
> +	result_data = (struct aer_broadcast_data *) data;
> +
> +	device_lock(&dev->dev);
> +	dev->error_state = result_data->state;
> +
> +	if (!dev->driver ||
> +		!dev->driver->err_handler ||
> +		!dev->driver->err_handler->error_detected) {
> +		if (result_data->state == pci_channel_io_frozen &&
> +			dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
> +			/*
> +			 * In case of fatal recovery, if one of down-
> +			 * stream device has no driver. We might be
> +			 * unable to recover because a later insmod
> +			 * of a driver for this device is unaware of
> +			 * its hw state.
> +			 */
> +			pci_printk(KERN_DEBUG, dev, "device has %s\n",
> +				   dev->driver ?
> +				   "no AER-aware driver" : "no driver");
> +		}
> +
> +		/*
> +		 * If there's any device in the subtree that does not
> +		 * have an error_detected callback, returning
> +		 * PCI_ERS_RESULT_NO_AER_DRIVER prevents calling of
> +		 * the subsequent mmio_enabled/slot_reset/resume
> +		 * callbacks of "any" device in the subtree. All the
> +		 * devices in the subtree are left in the error state
> +		 * without recovery.
> +		 */
> +
> +		if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
> +			vote = PCI_ERS_RESULT_NO_AER_DRIVER;
> +		else
> +			vote = PCI_ERS_RESULT_NONE;
> +	} else {
> +		err_handler = dev->driver->err_handler;
> +		vote = err_handler->error_detected(dev, result_data->state);
> +		pci_uevent_ers(dev, PCI_ERS_RESULT_NONE);
> +	}
> +
> +	result_data->result = merge_result(result_data->result, vote);
> +	device_unlock(&dev->dev);
> +	return 0;
> +}
> +
> +static int report_mmio_enabled(struct pci_dev *dev, void *data)
> +{
> +	pci_ers_result_t vote;
> +	const struct pci_error_handlers *err_handler;
> +	struct aer_broadcast_data *result_data;
> +
> +	result_data = (struct aer_broadcast_data *) data;
> +
> +	device_lock(&dev->dev);
> +	if (!dev->driver ||
> +		!dev->driver->err_handler ||
> +		!dev->driver->err_handler->mmio_enabled)
> +		goto out;
> +
> +	err_handler = dev->driver->err_handler;
> +	vote = err_handler->mmio_enabled(dev);
> +	result_data->result = merge_result(result_data->result, vote);
> +out:
> +	device_unlock(&dev->dev);
> +	return 0;
> +}
> +
> +static int report_slot_reset(struct pci_dev *dev, void *data)
> +{
> +	pci_ers_result_t vote;
> +	const struct pci_error_handlers *err_handler;
> +	struct aer_broadcast_data *result_data;
> +
> +	result_data = (struct aer_broadcast_data *) data;
> +
> +	device_lock(&dev->dev);
> +	if (!dev->driver ||
> +		!dev->driver->err_handler ||
> +		!dev->driver->err_handler->slot_reset)
> +		goto out;
> +
> +	err_handler = dev->driver->err_handler;
> +	vote = err_handler->slot_reset(dev);
> +	result_data->result = merge_result(result_data->result, vote);
> +out:
> +	device_unlock(&dev->dev);
> +	return 0;
> +}
> +
> +static int report_resume(struct pci_dev *dev, void *data)
> +{
> +	const struct pci_error_handlers *err_handler;
> +
> +	device_lock(&dev->dev);
> +	dev->error_state = pci_channel_io_normal;
> +
> +	if (!dev->driver ||
> +		!dev->driver->err_handler ||
> +		!dev->driver->err_handler->resume)
> +		goto out;
> +
> +	err_handler = dev->driver->err_handler;
> +	err_handler->resume(dev);
> +	pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED);
> +out:
> +	device_unlock(&dev->dev);
> +	return 0;
> +}
> +
> +/**
> + * default_reset_link - default reset function
> + * @dev: pointer to pci_dev data structure
> + *
> + * Invoked when performing link reset on a Downstream Port or a
> + * Root Port with no aer driver.
> + */
> +static pci_ers_result_t default_reset_link(struct pci_dev *dev)
> +{
> +	pci_reset_bridge_secondary_bus(dev);
> +	pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
> +	return PCI_ERS_RESULT_RECOVERED;
> +}
> +
> +static pci_ers_result_t reset_link(struct pci_dev *dev)
> +{
> +	struct pci_dev *udev;
> +	pci_ers_result_t status;
> +	struct pcie_port_service_driver *driver;
> +
> +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> +		/* Reset this port for all subordinates */
> +		udev = dev;
> +	} else {
> +		/* Reset the upstream component (likely downstream port) */
> +		udev = dev->bus->self;
> +	}
> +
> +#if IS_ENABLED(CONFIG_PCIEAER)
> +	/* Use the aer driver of the component firstly */
> +	driver = find_aer_service(udev);
> +#endif
> +
> +	if (driver && driver->reset_link) {
> +		status = driver->reset_link(udev);
> +	} else if (udev->has_secondary_link) {
> +		status = default_reset_link(udev);
> +	} else {
> +		pci_printk(KERN_DEBUG, dev, "no link-reset support at upstream 
> device %s\n",
> +			pci_name(udev));
> +		return PCI_ERS_RESULT_DISCONNECT;
> +	}
> +
> +	if (status != PCI_ERS_RESULT_RECOVERED) {
> +		pci_printk(KERN_DEBUG, dev, "link reset at upstream device %s 
> failed\n",
> +			pci_name(udev));
> +		return PCI_ERS_RESULT_DISCONNECT;
> +	}
> +
> +	return status;
> +}
> +
> +/**
> + * broadcast_error_message - handle message broadcast to downstream 
> drivers
> + * @dev: pointer to from where in a hierarchy message is broadcasted 
> down
> + * @state: error state
> + * @error_mesg: message to print
> + * @cb: callback to be broadcasted
> + *
> + * Invoked during error recovery process. Once being invoked, the 
> content
> + * of error severity will be broadcasted to all downstream drivers in 
> a
> + * hierarchy in question.
> + */
> +static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
> +	enum pci_channel_state state,
> +	char *error_mesg,
> +	int (*cb)(struct pci_dev *, void *))
> +{
> +	struct aer_broadcast_data result_data;
> +
> +	pci_printk(KERN_DEBUG, dev, "broadcast %s message\n", error_mesg);
> +	result_data.state = state;
> +	if (cb == report_error_detected)
> +		result_data.result = PCI_ERS_RESULT_CAN_RECOVER;
> +	else
> +		result_data.result = PCI_ERS_RESULT_RECOVERED;
> +
> +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> +		/*
> +		 * 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.
> +		 */
> +		if (cb == report_error_detected)
> +			dev->error_state = state;
> +		pci_walk_bus(dev->subordinate, cb, &result_data);
> +		if (cb == report_resume) {
> +			pci_cleanup_aer_uncorrect_error_status(dev);
> +			dev->error_state = pci_channel_io_normal;
> +		}
> +	} else {
> +		/*
> +		 * If the error is reported by an end point, we think this
> +		 * error is related to the upstream link of the end point.
> +		 */
> +		if (state == pci_channel_io_normal)
> +			/*
> +			 * the error is non fatal so the bus is ok, just invoke
> +			 * the callback for the function that logged the error.
> +			 */
> +			cb(dev, &result_data);
> +		else
> +			pci_walk_bus(dev->bus, cb, &result_data);
> +	}
> +
> +	return result_data.result;
> +}
> +
> +static pci_ers_result_t do_fatal_recovery(struct pci_dev *dev, int 
> severity)
> +{
> +	struct pci_dev *udev;
> +	struct pci_bus *parent;
> +	struct pci_dev *pdev, *temp;
> +	pci_ers_result_t result = PCI_ERS_RESULT_RECOVERED;
> +
> +	if (severity == AER_FATAL)
> +		pci_cleanup_aer_uncorrect_error_status(dev);
> +
> +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
> +		udev = dev;
> +	else
> +		udev = dev->bus->self;
> +
> +	parent = udev->subordinate;
> +	pci_lock_rescan_remove();
> +	list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
> +				 bus_list) {
> +		pci_dev_get(pdev);
> +		pci_dev_set_disconnected(pdev, NULL);
> +		if (pci_has_subordinate(pdev))
> +			pci_walk_bus(pdev->subordinate,
> +				     pci_dev_set_disconnected, NULL);
> +		pci_stop_and_remove_bus_device(pdev);
> +		pci_dev_put(pdev);
> +	}
> +
> +	result = reset_link(udev);
> +	if (result == PCI_ERS_RESULT_RECOVERED)
> +		if (pcie_wait_for_link(udev, true))
> +			pci_rescan_bus(udev->bus);
> +
> +	pci_unlock_rescan_remove();
> +
> +	return result;
> +}
> +
> +/**
> + * pcie_do_recovery - handle nonfatal/fatal error recovery process
> + * @dev: pointer to a pci_dev data structure of agent detecting an 
> error
> + * @severity: error severity type
> + *
> + * Invoked when an error is nonfatal/fatal. Once being invoked, 
> broadcast
> + * error detected message to all downstream drivers within a hierarchy 
> in
> + * question and return the returned code.
> + */
> +void pcie_do_recovery(struct pci_dev *dev, int severity)
> +{
> +	pci_ers_result_t status;
> +	enum pci_channel_state state;
> +
> +	if (severity == AER_FATAL) {
> +		status = do_fatal_recovery(dev, severity);
> +		if (status != PCI_ERS_RESULT_RECOVERED)
> +			goto failed;
> +		return;
> +	} else
> +		state = pci_channel_io_normal;
> +
> +	status = broadcast_error_message(dev,
> +			state,
> +			"error_detected",
> +			report_error_detected);
> +
> +	if (status == PCI_ERS_RESULT_CAN_RECOVER)
> +		status = broadcast_error_message(dev,
> +				state,
> +				"mmio_enabled",
> +				report_mmio_enabled);
> +
> +	if (status == PCI_ERS_RESULT_NEED_RESET) {
> +		/*
> +		 * TODO: Should call platform-specific
> +		 * functions to reset slot before calling
> +		 * drivers' slot_reset callbacks?
> +		 */
> +		status = broadcast_error_message(dev,
> +				state,
> +				"slot_reset",
> +				report_slot_reset);
> +	}
> +
> +	if (status != PCI_ERS_RESULT_RECOVERED)
> +		goto failed;
> +
> +	broadcast_error_message(dev,
> +				state,
> +				"resume",
> +				report_resume);
> +
> +	pci_info(dev, "AER: Device recovery successful\n");
> +	return;
> +
> +failed:
> +	pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
> +	/* TODO: Should kernel panic here? */
> +	pci_info(dev, "AER: Device recovery failed\n");
> +}
> diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
> index d0c6783..47c9824 100644
> --- a/drivers/pci/pcie/portdrv.h
> +++ b/drivers/pci/pcie/portdrv.h
> @@ -112,4 +112,5 @@ static inline bool pcie_pme_no_msi(void) { return 
> false; }
>  static inline void pcie_pme_interrupt_enable(struct pci_dev *dev, bool 
> en) {}
>  #endif /* !CONFIG_PCIE_PME */
> 
> +struct pcie_port_service_driver *find_aer_service(struct pci_dev 
> *dev);
>  #endif /* _PORTDRV_H_ */

Hi Bjorn,

I will be fixing kbuild error (for x86) along with the comments you 
might have.

Regards,
Oza.

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