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![Lukas Wunner](/assets/img/avatar_default.png)
When a hotplug driver calls pci_hp_register(), all steps necessary for registration are carried out in one go, including creation of a kobject and addition to sysfs. That's a problem for pciehp once it's converted to enable/disable the slot exclusively from the IRQ thread: The thread needs to be spawned after creation of the kobject (because it uses the kobject's name), but before addition to sysfs (because it will handle enable/disable requests submitted via sysfs). pci_hp_deregister() does offer a ->release callback that's invoked after deletion from sysfs and before destruction of the kobject. But because pci_hp_register() doesn't offer a counterpart, hotplug drivers' ->probe and ->remove code becomes asymmetric, which is error prone as recently discovered use-after-free bugs in pciehp's ->remove hook have shown. In a sense, this appears to be a case of the midlayer antipattern: "The core thesis of the "midlayer mistake" is that midlayers are bad and should not exist. That common functionality which it is so tempting to put in a midlayer should instead be provided as library routines which can [be] used, augmented, or ignored by each bottom level driver independently. Thus every subsystem that supports multiple implementations (or drivers) should provide a very thin top layer which calls directly into the bottom layer drivers, and a rich library of support code that eases the implementation of those drivers. This library is available to, but not forced upon, those drivers." -- Neil Brown (2009), https://lwn.net/Articles/336262/ The presence of midlayer traits in the PCI hotplug core might be ascribed to its age: When it was introduced in February 2002, the blessings of a library approach might not have been well known: https://git.kernel.org/tglx/history/c/a8a2069f432c For comparison, the driver core does offer split functions for creating a kobject (device_initialize()) and addition to sysfs (device_add()) as an alternative to carrying out everything at once (device_register()). This was introduced in October 2002: https://git.kernel.org/tglx/history/c/8b290eb19962 The odd ->release callback in the PCI hotplug core was added in 2003: https://git.kernel.org/tglx/history/c/69f8d663b595 Clearly, a library approach would not force every hotplug driver to implement a ->release callback, but rather allow the driver to remove the sysfs files, release its data structures and finally destroy the kobject. Alternatively, a driver may choose to remove everything with pci_hp_deregister(), then release its data structures. To this end, offer drivers pci_hp_initialize() and pci_hp_add() as a split-up version of pci_hp_register(). Likewise, offer pci_hp_del() and pci_hp_destroy() as a split-up version of pci_hp_deregister(). Eliminate the ->release callback and move its code into each driver's teardown routine. Declare pci_hp_deregister() void, in keeping with the usual kernel pattern that enablement can fail, but disablement cannot. It only returned an error if the caller passed in a NULL pointer or a slot which has never or is no longer registered or is sharing its name with another slot. Those would be bugs, so WARN about them. Few hotplug drivers actually checked the return value and those that did only printed a useless error message to dmesg. Remove that. For most drivers the conversion was straightforward since it doesn't matter whether the code in the ->release callback is executed before or after destruction of the kobject. But in the case of ibmphp, it was unclear to me whether setting slot_cur->ctrl and slot_cur->bus_on to NULL needs to happen before the kobject is destroyed, so I erred on the side of caution and ensured that the order stays the same. Another nontrivial case is pnv_php, I've found the list and kref logic difficult to understand, however my impression was that it is safe to delete the list element and drop the references until after the kobject is destroyed. Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86 Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Scott Murray <scott@spiteful.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Gavin Shan <gwshan@linux.vnet.ibm.com> Cc: Sebastian Ott <sebott@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Corentin Chary <corentin.chary@gmail.com> Cc: Darren Hart <dvhart@infradead.org> Cc: Andy Shevchenko <andy@infradead.org>
490 lines
11 KiB
C
490 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* PCI Hot Plug Controller Driver for RPA-compliant PPC64 platform.
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* Copyright (C) 2003 Linda Xie <lxie@us.ibm.com>
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*
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* All rights reserved.
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*
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* Send feedback to <lxie@us.ibm.com>
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/pci.h>
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#include <linux/pci_hotplug.h>
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#include <linux/smp.h>
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#include <linux/init.h>
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#include <linux/vmalloc.h>
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#include <asm/firmware.h>
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#include <asm/eeh.h> /* for eeh_add_device() */
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#include <asm/rtas.h> /* rtas_call */
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#include <asm/pci-bridge.h> /* for pci_controller */
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#include "../pci.h" /* for pci_add_new_bus */
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/* and pci_do_scan_bus */
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#include "rpaphp.h"
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bool rpaphp_debug;
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LIST_HEAD(rpaphp_slot_head);
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EXPORT_SYMBOL_GPL(rpaphp_slot_head);
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#define DRIVER_VERSION "0.1"
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#define DRIVER_AUTHOR "Linda Xie <lxie@us.ibm.com>"
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#define DRIVER_DESC "RPA HOT Plug PCI Controller Driver"
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#define MAX_LOC_CODE 128
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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MODULE_LICENSE("GPL");
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module_param_named(debug, rpaphp_debug, bool, 0644);
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/**
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* set_attention_status - set attention LED
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* @hotplug_slot: target &hotplug_slot
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* @value: LED control value
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*
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* echo 0 > attention -- set LED OFF
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* echo 1 > attention -- set LED ON
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* echo 2 > attention -- set LED ID(identify, light is blinking)
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*/
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static int set_attention_status(struct hotplug_slot *hotplug_slot, u8 value)
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{
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int rc;
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struct slot *slot = (struct slot *)hotplug_slot->private;
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switch (value) {
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case 0:
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case 1:
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case 2:
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break;
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default:
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value = 1;
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break;
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}
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rc = rtas_set_indicator(DR_INDICATOR, slot->index, value);
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if (!rc)
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hotplug_slot->info->attention_status = value;
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return rc;
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}
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/**
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* get_power_status - get power status of a slot
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* @hotplug_slot: slot to get status
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* @value: pointer to store status
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*/
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static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
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{
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int retval, level;
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struct slot *slot = (struct slot *)hotplug_slot->private;
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retval = rtas_get_power_level(slot->power_domain, &level);
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if (!retval)
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*value = level;
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return retval;
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}
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/**
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* get_attention_status - get attention LED status
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* @hotplug_slot: slot to get status
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* @value: pointer to store status
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*/
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static int get_attention_status(struct hotplug_slot *hotplug_slot, u8 *value)
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{
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struct slot *slot = (struct slot *)hotplug_slot->private;
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*value = slot->hotplug_slot->info->attention_status;
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return 0;
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}
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static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
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{
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struct slot *slot = (struct slot *)hotplug_slot->private;
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int rc, state;
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rc = rpaphp_get_sensor_state(slot, &state);
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*value = NOT_VALID;
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if (rc)
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return rc;
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if (state == EMPTY)
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*value = EMPTY;
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else if (state == PRESENT)
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*value = slot->state;
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return 0;
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}
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static enum pci_bus_speed get_max_bus_speed(struct slot *slot)
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{
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enum pci_bus_speed speed;
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switch (slot->type) {
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case 1:
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case 2:
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case 3:
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case 4:
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case 5:
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case 6:
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speed = PCI_SPEED_33MHz; /* speed for case 1-6 */
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break;
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case 7:
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case 8:
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speed = PCI_SPEED_66MHz;
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break;
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case 11:
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case 14:
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speed = PCI_SPEED_66MHz_PCIX;
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break;
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case 12:
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case 15:
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speed = PCI_SPEED_100MHz_PCIX;
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break;
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case 13:
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case 16:
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speed = PCI_SPEED_133MHz_PCIX;
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break;
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default:
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speed = PCI_SPEED_UNKNOWN;
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break;
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}
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return speed;
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}
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static int get_children_props(struct device_node *dn, const int **drc_indexes,
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const int **drc_names, const int **drc_types,
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const int **drc_power_domains)
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{
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const int *indexes, *names, *types, *domains;
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indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
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names = of_get_property(dn, "ibm,drc-names", NULL);
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types = of_get_property(dn, "ibm,drc-types", NULL);
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domains = of_get_property(dn, "ibm,drc-power-domains", NULL);
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if (!indexes || !names || !types || !domains) {
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/* Slot does not have dynamically-removable children */
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return -EINVAL;
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}
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if (drc_indexes)
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*drc_indexes = indexes;
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if (drc_names)
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/* &drc_names[1] contains NULL terminated slot names */
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*drc_names = names;
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if (drc_types)
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/* &drc_types[1] contains NULL terminated slot types */
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*drc_types = types;
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if (drc_power_domains)
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*drc_power_domains = domains;
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return 0;
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}
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/* Verify the existence of 'drc_name' and/or 'drc_type' within the
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* current node. First obtain it's my-drc-index property. Next,
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* obtain the DRC info from it's parent. Use the my-drc-index for
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* correlation, and obtain/validate the requested properties.
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*/
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static int rpaphp_check_drc_props_v1(struct device_node *dn, char *drc_name,
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char *drc_type, unsigned int my_index)
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{
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char *name_tmp, *type_tmp;
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const int *indexes, *names;
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const int *types, *domains;
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int i, rc;
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rc = get_children_props(dn->parent, &indexes, &names, &types, &domains);
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if (rc < 0) {
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return -EINVAL;
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}
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name_tmp = (char *) &names[1];
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type_tmp = (char *) &types[1];
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/* Iterate through parent properties, looking for my-drc-index */
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for (i = 0; i < be32_to_cpu(indexes[0]); i++) {
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if ((unsigned int) indexes[i + 1] == my_index)
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break;
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name_tmp += (strlen(name_tmp) + 1);
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type_tmp += (strlen(type_tmp) + 1);
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}
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if (((drc_name == NULL) || (drc_name && !strcmp(drc_name, name_tmp))) &&
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((drc_type == NULL) || (drc_type && !strcmp(drc_type, type_tmp))))
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return 0;
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return -EINVAL;
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}
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static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
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char *drc_type, unsigned int my_index)
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{
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struct property *info;
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unsigned int entries;
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struct of_drc_info drc;
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const __be32 *value;
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char cell_drc_name[MAX_DRC_NAME_LEN];
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int j, fndit;
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info = of_find_property(dn->parent, "ibm,drc-info", NULL);
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if (info == NULL)
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return -EINVAL;
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value = of_prop_next_u32(info, NULL, &entries);
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if (!value)
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return -EINVAL;
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for (j = 0; j < entries; j++) {
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of_read_drc_info_cell(&info, &value, &drc);
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/* Should now know end of current entry */
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if (my_index > drc.last_drc_index)
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continue;
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fndit = 1;
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break;
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}
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/* Found it */
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if (fndit)
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sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix,
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my_index);
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if (((drc_name == NULL) ||
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(drc_name && !strcmp(drc_name, cell_drc_name))) &&
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((drc_type == NULL) ||
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(drc_type && !strcmp(drc_type, drc.drc_type))))
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return 0;
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return -EINVAL;
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}
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int rpaphp_check_drc_props(struct device_node *dn, char *drc_name,
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char *drc_type)
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{
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const unsigned int *my_index;
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my_index = of_get_property(dn, "ibm,my-drc-index", NULL);
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if (!my_index) {
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/* Node isn't DLPAR/hotplug capable */
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return -EINVAL;
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}
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if (firmware_has_feature(FW_FEATURE_DRC_INFO))
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return rpaphp_check_drc_props_v2(dn, drc_name, drc_type,
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*my_index);
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else
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return rpaphp_check_drc_props_v1(dn, drc_name, drc_type,
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*my_index);
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}
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EXPORT_SYMBOL_GPL(rpaphp_check_drc_props);
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static int is_php_type(char *drc_type)
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{
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unsigned long value;
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char *endptr;
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/* PCI Hotplug nodes have an integer for drc_type */
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value = simple_strtoul(drc_type, &endptr, 10);
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if (endptr == drc_type)
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return 0;
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return 1;
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}
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/**
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* is_php_dn() - return 1 if this is a hotpluggable pci slot, else 0
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* @dn: target &device_node
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* @indexes: passed to get_children_props()
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* @names: passed to get_children_props()
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* @types: returned from get_children_props()
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* @power_domains:
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*
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* This routine will return true only if the device node is
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* a hotpluggable slot. This routine will return false
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* for built-in pci slots (even when the built-in slots are
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* dlparable.)
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*/
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static int is_php_dn(struct device_node *dn, const int **indexes,
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const int **names, const int **types, const int **power_domains)
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{
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const int *drc_types;
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int rc;
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rc = get_children_props(dn, indexes, names, &drc_types, power_domains);
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if (rc < 0)
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return 0;
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if (!is_php_type((char *) &drc_types[1]))
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return 0;
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*types = drc_types;
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return 1;
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}
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/**
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* rpaphp_add_slot -- declare a hotplug slot to the hotplug subsystem.
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* @dn: device node of slot
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*
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* This subroutine will register a hotpluggable slot with the
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* PCI hotplug infrastructure. This routine is typically called
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* during boot time, if the hotplug slots are present at boot time,
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* or is called later, by the dlpar add code, if the slot is
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* being dynamically added during runtime.
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*
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* If the device node points at an embedded (built-in) slot, this
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* routine will just return without doing anything, since embedded
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* slots cannot be hotplugged.
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*
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* To remove a slot, it suffices to call rpaphp_deregister_slot().
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*/
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int rpaphp_add_slot(struct device_node *dn)
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{
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struct slot *slot;
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int retval = 0;
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int i;
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const int *indexes, *names, *types, *power_domains;
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char *name, *type;
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if (!dn->name || strcmp(dn->name, "pci"))
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return 0;
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/* If this is not a hotplug slot, return without doing anything. */
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if (!is_php_dn(dn, &indexes, &names, &types, &power_domains))
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return 0;
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dbg("Entry %s: dn=%pOF\n", __func__, dn);
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/* register PCI devices */
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name = (char *) &names[1];
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type = (char *) &types[1];
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for (i = 0; i < be32_to_cpu(indexes[0]); i++) {
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int index;
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index = be32_to_cpu(indexes[i + 1]);
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slot = alloc_slot_struct(dn, index, name,
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be32_to_cpu(power_domains[i + 1]));
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if (!slot)
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return -ENOMEM;
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slot->type = simple_strtoul(type, NULL, 10);
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dbg("Found drc-index:0x%x drc-name:%s drc-type:%s\n",
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index, name, type);
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retval = rpaphp_enable_slot(slot);
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if (!retval)
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retval = rpaphp_register_slot(slot);
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if (retval)
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dealloc_slot_struct(slot);
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name += strlen(name) + 1;
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type += strlen(type) + 1;
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}
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dbg("%s - Exit: rc[%d]\n", __func__, retval);
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/* XXX FIXME: reports a failure only if last entry in loop failed */
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return retval;
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}
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EXPORT_SYMBOL_GPL(rpaphp_add_slot);
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static void __exit cleanup_slots(void)
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{
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struct slot *slot, *next;
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/*
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* Unregister all of our slots with the pci_hotplug subsystem,
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* and free up all memory that we had allocated.
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*/
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list_for_each_entry_safe(slot, next, &rpaphp_slot_head,
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rpaphp_slot_list) {
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list_del(&slot->rpaphp_slot_list);
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pci_hp_deregister(slot->hotplug_slot);
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dealloc_slot_struct(slot);
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}
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return;
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}
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static int __init rpaphp_init(void)
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{
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struct device_node *dn;
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info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
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for_each_node_by_name(dn, "pci")
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rpaphp_add_slot(dn);
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return 0;
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}
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static void __exit rpaphp_exit(void)
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{
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cleanup_slots();
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}
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static int enable_slot(struct hotplug_slot *hotplug_slot)
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{
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struct slot *slot = (struct slot *)hotplug_slot->private;
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int state;
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int retval;
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if (slot->state == CONFIGURED)
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return 0;
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retval = rpaphp_get_sensor_state(slot, &state);
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if (retval)
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return retval;
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if (state == PRESENT) {
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pci_lock_rescan_remove();
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pci_hp_add_devices(slot->bus);
|
|
pci_unlock_rescan_remove();
|
|
slot->state = CONFIGURED;
|
|
} else if (state == EMPTY) {
|
|
slot->state = EMPTY;
|
|
} else {
|
|
err("%s: slot[%s] is in invalid state\n", __func__, slot->name);
|
|
slot->state = NOT_VALID;
|
|
return -EINVAL;
|
|
}
|
|
|
|
slot->bus->max_bus_speed = get_max_bus_speed(slot);
|
|
return 0;
|
|
}
|
|
|
|
static int disable_slot(struct hotplug_slot *hotplug_slot)
|
|
{
|
|
struct slot *slot = (struct slot *)hotplug_slot->private;
|
|
if (slot->state == NOT_CONFIGURED)
|
|
return -EINVAL;
|
|
|
|
pci_lock_rescan_remove();
|
|
pci_hp_remove_devices(slot->bus);
|
|
pci_unlock_rescan_remove();
|
|
vm_unmap_aliases();
|
|
|
|
slot->state = NOT_CONFIGURED;
|
|
return 0;
|
|
}
|
|
|
|
struct hotplug_slot_ops rpaphp_hotplug_slot_ops = {
|
|
.enable_slot = enable_slot,
|
|
.disable_slot = disable_slot,
|
|
.set_attention_status = set_attention_status,
|
|
.get_power_status = get_power_status,
|
|
.get_attention_status = get_attention_status,
|
|
.get_adapter_status = get_adapter_status,
|
|
};
|
|
|
|
module_init(rpaphp_init);
|
|
module_exit(rpaphp_exit);
|