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PCI: acpiphp: Protect acpiphp data structures from concurrent updates
Now acpiphp_enumerate_slots() and acpiphp_remove_slots() may be invoked concurrently by the PCI core, so add a bridge_mutex and reference count mechanism to protect acpiphp bridge/slot/function data structures. To avoid deadlock, handle_hotplug_event_bridge() will requeue the hotplug event onto the kacpi_hotplug_wq by calling alloc_acpi_hp_work(). But the workaround has introduced a minor race window because the 'bridge' passed to _handle_hotplug_event_bridge() may have already been destroyed when _handle_hotplug_event_bridge() is actually executed by the kacpi_hotplug_wq. So hold a reference count on the passed 'bridge'. Fix the same issue for handle_hotplug_event_func() too. Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Signed-off-by: Yijing Wang <wangyijing@huawei.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Yinghai Lu <yinghai@kernel.org> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Toshi Kani <toshi.kani@hp.com>
This commit is contained in:
Jiang Liu
Bjorn Helgaas
parent
ad41dd9dd0
commit
3d54a3160f
@ -74,6 +74,7 @@ static inline const char *slot_name(struct slot *slot)
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struct acpiphp_bridge {
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struct list_head list;
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struct list_head slots;
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struct kref ref;
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acpi_handle handle;
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/* Ejectable PCI-to-PCI bridge (PCI bridge and PCI function) */
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@ -54,6 +54,7 @@
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#include "acpiphp.h"
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static LIST_HEAD(bridge_list);
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static DEFINE_MUTEX(bridge_mutex);
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#define MY_NAME "acpiphp_glue"
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@ -61,6 +62,7 @@ static void handle_hotplug_event_bridge (acpi_handle, u32, void *);
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static void acpiphp_sanitize_bus(struct pci_bus *bus);
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static void acpiphp_set_hpp_values(struct pci_bus *bus);
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static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
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static void free_bridge(struct kref *kref);
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/* callback routine to check for the existence of a pci dock device */
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static acpi_status
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@ -76,6 +78,39 @@ is_pci_dock_device(acpi_handle handle, u32 lvl, void *context, void **rv)
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}
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}
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static inline void get_bridge(struct acpiphp_bridge *bridge)
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{
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kref_get(&bridge->ref);
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}
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static inline void put_bridge(struct acpiphp_bridge *bridge)
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{
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kref_put(&bridge->ref, free_bridge);
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}
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static void free_bridge(struct kref *kref)
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{
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struct acpiphp_bridge *bridge;
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struct acpiphp_slot *slot, *next;
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struct acpiphp_func *func, *tmp;
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bridge = container_of(kref, struct acpiphp_bridge, ref);
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list_for_each_entry_safe(slot, next, &bridge->slots, node) {
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list_for_each_entry_safe(func, tmp, &slot->funcs, sibling) {
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kfree(func);
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}
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kfree(slot);
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}
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/* Release reference acquired by acpiphp_bridge_handle_to_function() */
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if ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)
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put_bridge(bridge->func->slot->bridge);
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put_device(&bridge->pci_bus->dev);
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pci_dev_put(bridge->pci_dev);
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kfree(bridge);
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}
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/*
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* the _DCK method can do funny things... and sometimes not
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* hah-hah funny.
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@ -171,7 +206,7 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
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device = (adr >> 16) & 0xffff;
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function = adr & 0xffff;
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pdev = pbus->self;
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pdev = bridge->pci_dev;
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if (pdev && device_is_managed_by_native_pciehp(pdev))
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return AE_OK;
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@ -179,7 +214,6 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
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if (!newfunc)
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return AE_NO_MEMORY;
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INIT_LIST_HEAD(&newfunc->sibling);
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newfunc->handle = handle;
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newfunc->function = function;
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@ -229,7 +263,9 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
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INIT_LIST_HEAD(&slot->funcs);
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mutex_init(&slot->crit_sect);
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mutex_lock(&bridge_mutex);
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list_add_tail(&slot->node, &bridge->slots);
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mutex_unlock(&bridge_mutex);
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bridge->nr_slots++;
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dbg("found ACPI PCI Hotplug slot %llu at PCI %04x:%02x:%02x\n",
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@ -247,7 +283,9 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
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}
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newfunc->slot = slot;
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mutex_lock(&bridge_mutex);
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list_add_tail(&newfunc->sibling, &slot->funcs);
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mutex_unlock(&bridge_mutex);
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if (pci_bus_read_dev_vendor_id(pbus, PCI_DEVFN(device, function),
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&val, 60*1000))
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@ -288,7 +326,9 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
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err_exit:
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bridge->nr_slots--;
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mutex_lock(&bridge_mutex);
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list_del(&slot->node);
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mutex_unlock(&bridge_mutex);
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kfree(slot);
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kfree(newfunc);
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@ -313,13 +353,17 @@ static void init_bridge_misc(struct acpiphp_bridge *bridge)
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acpi_status status;
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/* must be added to the list prior to calling register_slot */
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mutex_lock(&bridge_mutex);
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list_add(&bridge->list, &bridge_list);
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mutex_unlock(&bridge_mutex);
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/* register all slot objects under this bridge */
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status = acpi_walk_namespace(ACPI_TYPE_DEVICE, bridge->handle, (u32)1,
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register_slot, NULL, bridge, NULL);
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if (ACPI_FAILURE(status)) {
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mutex_lock(&bridge_mutex);
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list_del(&bridge->list);
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mutex_unlock(&bridge_mutex);
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return;
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}
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@ -349,16 +393,21 @@ static struct acpiphp_func *acpiphp_bridge_handle_to_function(acpi_handle handle
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{
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struct acpiphp_bridge *bridge;
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struct acpiphp_slot *slot;
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struct acpiphp_func *func;
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struct acpiphp_func *func = NULL;
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mutex_lock(&bridge_mutex);
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list_for_each_entry(bridge, &bridge_list, list) {
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list_for_each_entry(slot, &bridge->slots, node) {
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list_for_each_entry(func, &slot->funcs, sibling) {
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if (func->handle == handle)
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if (func->handle == handle) {
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get_bridge(func->slot->bridge);
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mutex_unlock(&bridge_mutex);
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return func;
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}
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}
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}
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}
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mutex_unlock(&bridge_mutex);
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return NULL;
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}
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@ -368,17 +417,22 @@ static struct acpiphp_bridge *acpiphp_handle_to_bridge(acpi_handle handle)
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{
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struct acpiphp_bridge *bridge;
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mutex_lock(&bridge_mutex);
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list_for_each_entry(bridge, &bridge_list, list)
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if (bridge->handle == handle)
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if (bridge->handle == handle) {
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get_bridge(bridge);
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mutex_unlock(&bridge_mutex);
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return bridge;
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}
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mutex_unlock(&bridge_mutex);
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return NULL;
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}
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static void cleanup_bridge(struct acpiphp_bridge *bridge)
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{
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struct acpiphp_slot *slot, *next;
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struct acpiphp_func *func, *tmp;
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struct acpiphp_slot *slot;
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struct acpiphp_func *func;
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acpi_status status;
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acpi_handle handle = bridge->handle;
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@ -399,8 +453,8 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
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err("failed to install interrupt notify handler\n");
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}
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list_for_each_entry_safe(slot, next, &bridge->slots, node) {
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list_for_each_entry_safe(func, tmp, &slot->funcs, sibling) {
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list_for_each_entry(slot, &bridge->slots, node) {
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list_for_each_entry(func, &slot->funcs, sibling) {
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if (is_dock_device(func->handle)) {
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unregister_hotplug_dock_device(func->handle);
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unregister_dock_notifier(&func->nb);
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@ -412,18 +466,13 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
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if (ACPI_FAILURE(status))
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err("failed to remove notify handler\n");
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}
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list_del(&func->sibling);
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kfree(func);
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}
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acpiphp_unregister_hotplug_slot(slot);
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list_del(&slot->funcs);
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kfree(slot);
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}
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put_device(&bridge->pci_bus->dev);
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pci_dev_put(bridge->pci_dev);
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mutex_lock(&bridge_mutex);
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list_del(&bridge->list);
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kfree(bridge);
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mutex_unlock(&bridge_mutex);
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}
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static int power_on_slot(struct acpiphp_slot *slot)
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@ -620,7 +669,6 @@ static int __ref enable_device(struct acpiphp_slot *slot)
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struct pci_dev *dev;
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struct pci_bus *bus = slot->bridge->pci_bus;
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struct acpiphp_func *func;
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int retval = 0;
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int num, max, pass;
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if (slot->flags & SLOT_ENABLED)
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@ -680,7 +728,7 @@ static int __ref enable_device(struct acpiphp_slot *slot)
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err_exit:
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return retval;
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return 0;
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}
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/* return first device in slot, acquiring a reference on it */
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@ -897,6 +945,7 @@ check_sub_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
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dbg("%s: re-enumerating slots under %s\n",
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__func__, objname);
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acpiphp_check_bridge(bridge);
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put_bridge(bridge);
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}
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return AE_OK ;
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}
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@ -974,6 +1023,7 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
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acpi_scan_lock_release();
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kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
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put_bridge(bridge);
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}
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/**
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@ -987,6 +1037,8 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
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static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
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void *context)
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{
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struct acpiphp_bridge *bridge = context;
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/*
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* Currently the code adds all hotplug events to the kacpid_wq
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* queue when it should add hotplug events to the kacpi_hotplug_wq.
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@ -995,6 +1047,7 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
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* For now just re-add this work to the kacpi_hotplug_wq so we
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* don't deadlock on hotplug actions.
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*/
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get_bridge(bridge);
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alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_bridge);
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}
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@ -1049,6 +1102,7 @@ static void _handle_hotplug_event_func(struct work_struct *work)
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acpi_scan_lock_release();
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kfree(hp_work); /* allocated in handle_hotplug_event_func */
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put_bridge(func->slot->bridge);
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}
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/**
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@ -1062,6 +1116,8 @@ static void _handle_hotplug_event_func(struct work_struct *work)
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static void handle_hotplug_event_func(acpi_handle handle, u32 type,
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void *context)
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{
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struct acpiphp_func *func = context;
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/*
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* Currently the code adds all hotplug events to the kacpid_wq
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* queue when it should add hotplug events to the kacpi_hotplug_wq.
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@ -1070,6 +1126,7 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type,
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* For now just re-add this work to the kacpi_hotplug_wq so we
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* don't deadlock on hotplug actions.
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*/
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get_bridge(func->slot->bridge);
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alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_func);
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}
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@ -1095,6 +1152,7 @@ void acpiphp_enumerate_slots(struct pci_bus *bus, acpi_handle handle)
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}
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INIT_LIST_HEAD(&bridge->slots);
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kref_init(&bridge->ref);
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bridge->handle = handle;
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bridge->pci_dev = pci_dev_get(bus->self);
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bridge->pci_bus = bus;
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@ -1128,6 +1186,7 @@ void acpiphp_remove_slots(struct pci_bus *bus)
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list_for_each_entry_safe(bridge, tmp, &bridge_list, list)
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if (bridge->pci_bus == bus) {
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cleanup_bridge(bridge);
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put_bridge(bridge);
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break;
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}
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}
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