Commit 1010b4c0 authored by Timothy Pearson's avatar Timothy Pearson Committed by Madhavan Srinivasan
Browse files

powerpc/eeh: Make EEH driver device hotplug safe 



Multiple race conditions existed between the PCIe hotplug driver and the
EEH driver, leading to a variety of kernel oopses of the same general
nature:

<pcie device unplug>
<eeh driver trigger>
<hotplug removal trigger>
<pcie tree reconfiguration>
<eeh recovery next step>
<oops in EEH driver bus iteration loop>

A second class of oops is also seen when the underlying bus disappears
during device recovery.

Refactor the EEH module to be PCI rescan and remove safe.  Also clean
up a few minor formatting / readability issues.

Signed-off-by: default avatarTimothy Pearson <tpearson@raptorengineering.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/1334208367.1359861.1752615503144.JavaMail.zimbra@raptorengineeringinc.com
parent e82b34ee

arch/powerpc/kernel/eeh_driver.c

+32 −16
Original line number Diff line number Diff line
@@ -257,13 +257,12 @@ static void eeh_pe_report_edev(struct eeh_dev *edev, eeh_report_fn fn, 
	struct pci_driver *driver;

	enum pci_ers_result new_result;



	pci_lock_rescan_remove();

	pdev = edev->pdev;

	if (pdev)

		get_device(&pdev->dev);

	pci_unlock_rescan_remove();

	if (!pdev) {

		eeh_edev_info(edev, "no device");

		*result = PCI_ERS_RESULT_DISCONNECT;

		return;

	}

	device_lock(&pdev->dev);
@@ -304,7 +303,8 @@ static void eeh_pe_report(const char *name, struct eeh_pe *root, 
	struct eeh_dev *edev, *tmp;



	pr_info("EEH: Beginning: '%s'\n", name);

	eeh_for_each_pe(root, pe) eeh_pe_for_each_dev(pe, edev, tmp)

	eeh_for_each_pe(root, pe)

		eeh_pe_for_each_dev(pe, edev, tmp)

			eeh_pe_report_edev(edev, fn, result);

	if (result)

		pr_info("EEH: Finished:'%s' with aggregate recovery state:'%s'\n",
@@ -383,6 +383,8 @@ static void eeh_dev_restore_state(struct eeh_dev *edev, void *userdata) 
	if (!edev)

		return;



	pci_lock_rescan_remove();



	/*

	 * The content in the config space isn't saved because

	 * the blocked config space on some adapters. We have
@@ -393,14 +395,19 @@ static void eeh_dev_restore_state(struct eeh_dev *edev, void *userdata) 
		if (list_is_last(&edev->entry, &edev->pe->edevs))

			eeh_pe_restore_bars(edev->pe);



		pci_unlock_rescan_remove();

		return;

	}



	pdev = eeh_dev_to_pci_dev(edev);

	if (!pdev)

	if (!pdev) {

		pci_unlock_rescan_remove();

		return;

	}



	pci_restore_state(pdev);



	pci_unlock_rescan_remove();

}



/**
@@ -647,9 +654,7 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus, 
	if (any_passed || driver_eeh_aware || (pe->type & EEH_PE_VF)) {

		eeh_pe_dev_traverse(pe, eeh_rmv_device, rmv_data);

	} else {

		pci_lock_rescan_remove();

		pci_hp_remove_devices(bus);

		pci_unlock_rescan_remove();

	}



	/*
@@ -665,8 +670,6 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus, 
	if (rc)

		return rc;



	pci_lock_rescan_remove();



	/* Restore PE */

	eeh_ops->configure_bridge(pe);

	eeh_pe_restore_bars(pe);
@@ -674,7 +677,6 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus, 
	/* Clear frozen state */

	rc = eeh_clear_pe_frozen_state(pe, false);

	if (rc) {

		pci_unlock_rescan_remove();

		return rc;

	}
@@ -709,7 +711,6 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus, 
	pe->tstamp = tstamp;

	pe->freeze_count = cnt;



	pci_unlock_rescan_remove();

	return 0;

}
@@ -843,10 +844,13 @@ void eeh_handle_normal_event(struct eeh_pe *pe) 
		{LIST_HEAD_INIT(rmv_data.removed_vf_list), 0};

	int devices = 0;



	pci_lock_rescan_remove();



	bus = eeh_pe_bus_get(pe);

	if (!bus) {

		pr_err("%s: Cannot find PCI bus for PHB#%x-PE#%x\n",

			__func__, pe->phb->global_number, pe->addr);

		pci_unlock_rescan_remove();

		return;

	}
@@ -1094,10 +1098,15 @@ void eeh_handle_normal_event(struct eeh_pe *pe) 
		eeh_pe_state_clear(pe, EEH_PE_PRI_BUS, true);

		eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);



		pci_lock_rescan_remove();

		bus = eeh_pe_bus_get(pe);

		if (bus)

			pci_hp_remove_devices(bus);

		pci_unlock_rescan_remove();

		else

			pr_err("%s: PCI bus for PHB#%x-PE#%x disappeared\n",

				__func__, pe->phb->global_number, pe->addr);



		/* The passed PE should no longer be used */

		pci_unlock_rescan_remove();

		return;

	}
@@ -1114,6 +1123,8 @@ void eeh_handle_normal_event(struct eeh_pe *pe) 
			eeh_clear_slot_attention(edev->pdev);



	eeh_pe_state_clear(pe, EEH_PE_RECOVERING, true);



	pci_unlock_rescan_remove();

}



/**
@@ -1132,6 +1143,7 @@ void eeh_handle_special_event(void) 
	unsigned long flags;

	int rc;



	pci_lock_rescan_remove();



	do {

		rc = eeh_ops->next_error(&pe);
@@ -1171,10 +1183,12 @@ void eeh_handle_special_event(void) 


			break;

		case EEH_NEXT_ERR_NONE:

			pci_unlock_rescan_remove();

			return;

		default:

			pr_warn("%s: Invalid value %d from next_error()\n",

				__func__, rc);

			pci_unlock_rescan_remove();

			return;

		}
@@ -1186,7 +1200,9 @@ void eeh_handle_special_event(void) 
		if (rc == EEH_NEXT_ERR_FROZEN_PE ||

		    rc == EEH_NEXT_ERR_FENCED_PHB) {

			eeh_pe_state_mark(pe, EEH_PE_RECOVERING);

			pci_unlock_rescan_remove();

			eeh_handle_normal_event(pe);

			pci_lock_rescan_remove();

		} else {

			eeh_for_each_pe(pe, tmp_pe)

				eeh_pe_for_each_dev(tmp_pe, edev, tmp_edev)
@@ -1199,7 +1215,6 @@ void eeh_handle_special_event(void) 
				eeh_report_failure, NULL);

			eeh_set_channel_state(pe, pci_channel_io_perm_failure);



			pci_lock_rescan_remove();

			list_for_each_entry(hose, &hose_list, list_node) {

				phb_pe = eeh_phb_pe_get(hose);

				if (!phb_pe ||
@@ -1218,7 +1233,6 @@ void eeh_handle_special_event(void) 
				}

				pci_hp_remove_devices(bus);

			}

			pci_unlock_rescan_remove();

		}



		/*
@@ -1228,4 +1242,6 @@ void eeh_handle_special_event(void) 
		if (rc == EEH_NEXT_ERR_DEAD_IOC)

			break;

	} while (rc != EEH_NEXT_ERR_NONE);



	pci_unlock_rescan_remove();

}

arch/powerpc/kernel/eeh_pe.c

+6 −4
Original line number Diff line number Diff line
@@ -671,11 +671,13 @@ static void eeh_bridge_check_link(struct eeh_dev *edev) 
	eeh_ops->write_config(edev, cap + PCI_EXP_LNKCTL, 2, val);



	/* Check link */

	if (edev->pdev) {

		if (!edev->pdev->link_active_reporting) {

			eeh_edev_dbg(edev, "No link reporting capability\n");

			msleep(1000);

			return;

		}

	}



	/* Wait the link is up until timeout (5s) */

	timeout = 0;