ACPI / hotplug / PCI: Unified notify handler for hotplug events

Using the hotplug context objects introduced previously rework the
ACPI-based PCI hotplug (ACPIPHP) core code so that all notifications
for ACPI device objects corresponding to the hotplug PCI devices are
handled by one function, handle_hotplug_event(), which recognizes
whether it has to handle a bridge or a function.

In addition to code size reduction it allows some ugly pieces of code
where notify handlers have to be uninstalled and installed again to
go away.  Moreover, it fixes a theoretically possible race between
handle_hotplug_event() and free_bridge() tearing down data structures
for the same handle.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

diff --git a/drivers/pci/hotplug/acpiphp.h b/drivers/pci/hotplug/acpiphp.h
index f946e47eca7c593ec8d783a35a92dbc7b2f057c5..b96a8a9c39c7ce33078401f89b49d2520abb4fb8 100644 (file)
--- a/drivers/pci/hotplug/acpiphp.h
+++ b/drivers/pci/hotplug/acpiphp.h
@@ -136,6 +136,7 @@ struct acpiphp_context {
        struct acpiphp_func *func;
        struct acpiphp_bridge *bridge;
        unsigned int refcount;
+       bool handler_for_func;
 };
 
 /*

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index a0c518c2185e6295bc1cefe87e88500a7a013d6b..ef7b25c1db57e0f1f0be85f39e0ed4a20d40a128 100644 (file)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -59,11 +59,10 @@ static DEFINE_MUTEX(acpiphp_context_lock);
 
 #define MY_NAME "acpiphp_glue"
 
-static void handle_hotplug_event_bridge (acpi_handle, u32, void *);
+static void handle_hotplug_event(acpi_handle handle, u32 type, void *data);
 static void acpiphp_sanitize_bus(struct pci_bus *bus);
 static void acpiphp_set_hpp_values(struct pci_bus *bus);
 static void hotplug_event_func(acpi_handle handle, u32 type, void *context);
-static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
 static void free_bridge(struct kref *kref);
 
 /* callback routine to check for the existence of a pci dock device */
@@ -179,13 +178,13 @@ static void free_bridge(struct kref *kref)
                kfree(slot);
        }
 
+       context = bridge->context;
        /* Release the reference acquired by acpiphp_enumerate_slots(). */
-       if ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)
+       if (context->handler_for_func)
                put_bridge(bridge->func->slot->bridge);
 
        put_device(&bridge->pci_bus->dev);
        pci_dev_put(bridge->pci_dev);
-       context = bridge->context;
        context->bridge = NULL;
        acpiphp_put_context(context);
        kfree(bridge);
@@ -414,12 +413,12 @@ static acpi_status register_slot(acpi_handle handle, u32 lvl, void *data,
 
        /* install notify handler */
        if (!(newfunc->flags & FUNC_HAS_DCK)) {
-               status = acpi_install_notify_handler(handle,
-                                            ACPI_SYSTEM_NOTIFY,
-                                            handle_hotplug_event_func,
-                                            newfunc);
-
-               if (ACPI_FAILURE(status))
+               status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
+                                                    handle_hotplug_event,
+                                                    context);
+               if (ACPI_SUCCESS(status))
+                       context->handler_for_func = true;
+               else
                        err("failed to register interrupt notify handler\n");
        }
 
@@ -476,32 +475,23 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
        acpi_status status;
        acpi_handle handle = bridge->handle;
 
-       if (!pci_is_root_bus(bridge->pci_bus)) {
-               status = acpi_remove_notify_handler(handle,
-                                           ACPI_SYSTEM_NOTIFY,
-                                           handle_hotplug_event_bridge);
+       if (!bridge->context->handler_for_func) {
+               status = acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
+                                                   handle_hotplug_event);
                if (ACPI_FAILURE(status))
                        err("failed to remove notify handler\n");
        }
 
-       if ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func) {
-               status = acpi_install_notify_handler(bridge->func->handle,
-                                               ACPI_SYSTEM_NOTIFY,
-                                               handle_hotplug_event_func,
-                                               bridge->func);
-               if (ACPI_FAILURE(status))
-                       err("failed to install interrupt notify handler\n");
-       }
-
        list_for_each_entry(slot, &bridge->slots, node) {
                list_for_each_entry(func, &slot->funcs, sibling) {
                        if (is_dock_device(func->handle)) {
                                unregister_hotplug_dock_device(func->handle);
                        }
                        if (!(func->flags & FUNC_HAS_DCK)) {
+                               func->context->handler_for_func = false;
                                status = acpi_remove_notify_handler(func->handle,
-                                               ACPI_SYSTEM_NOTIFY,
-                                               handle_hotplug_event_func);
+                                                       ACPI_SYSTEM_NOTIFY,
+                                                       handle_hotplug_event);
                                if (ACPI_FAILURE(status))
                                        err("failed to remove notify handler\n");
                        }
@@ -1071,31 +1061,6 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
        put_bridge(bridge);
 }
 
-/**
- * handle_hotplug_event_bridge - handle ACPI event on bridges
- * @handle: Notify()'ed acpi_handle
- * @type: Notify code
- * @context: pointer to acpiphp_bridge structure
- *
- * Handles ACPI event notification on {host,p2p} bridges.
- */
-static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
-                                       void *context)
-{
-       struct acpiphp_bridge *bridge = context;
-
-       /*
-        * Currently the code adds all hotplug events to the kacpid_wq
-        * queue when it should add hotplug events to the kacpi_hotplug_wq.
-        * The proper way to fix this is to reorganize the code so that
-        * drivers (dock, etc.) do not call acpi_os_execute(), etc.
-        * For now just re-add this work to the kacpi_hotplug_wq so we
-        * don't deadlock on hotplug actions.
-        */
-       get_bridge(bridge);
-       alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_bridge);
-}
-
 static void hotplug_event_func(acpi_handle handle, u32 type, void *context)
 {
        struct acpiphp_func *func = context;
@@ -1153,17 +1118,33 @@ static void _handle_hotplug_event_func(struct work_struct *work)
 }
 
 /**
- * handle_hotplug_event_func - handle ACPI event on functions (i.e. slots)
+ * handle_hotplug_event - handle ACPI hotplug event
  * @handle: Notify()'ed acpi_handle
  * @type: Notify code
- * @context: pointer to acpiphp_func structure
+ * @data: pointer to acpiphp_context structure
  *
  * Handles ACPI event notification on slots.
  */
-static void handle_hotplug_event_func(acpi_handle handle, u32 type,
-                                     void *context)
+static void handle_hotplug_event(acpi_handle handle, u32 type, void *data)
 {
-       struct acpiphp_func *func = context;
+       struct acpiphp_context *context;
+       void (*work_func)(struct work_struct *work) = NULL;
+
+       mutex_lock(&acpiphp_context_lock);
+       context = acpiphp_get_context(handle);
+       if (context) {
+               if (context->bridge) {
+                       get_bridge(context->bridge);
+                       data = context->bridge;
+                       work_func = _handle_hotplug_event_bridge;
+               } else if (context->func) {
+                       get_bridge(context->func->slot->bridge);
+                       data = context->func;
+                       work_func = _handle_hotplug_event_func;
+               }
+               acpiphp_put_context(context);
+       }
+       mutex_unlock(&acpiphp_context_lock);
 
        /*
         * Currently the code adds all hotplug events to the kacpid_wq
@@ -1173,8 +1154,8 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type,
         * For now just re-add this work to the kacpi_hotplug_wq so we
         * don't deadlock on hotplug actions.
         */
-       get_bridge(func->slot->bridge);
-       alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_func);
+       if (work_func)
+               alloc_acpi_hp_work(handle, type, data, work_func);
 }
 
 /*
@@ -1245,33 +1226,24 @@ void acpiphp_enumerate_slots(struct pci_bus *bus)
        if (pci_is_root_bus(bridge->pci_bus))
                return;
 
-       /* install notify handler for P2P bridges */
-       status = acpi_install_notify_handler(bridge->handle, ACPI_SYSTEM_NOTIFY,
-                                            handle_hotplug_event_bridge,
-                                            bridge);
-       if (ACPI_FAILURE(status)) {
-               acpi_handle_err(bridge->handle,
-                               "failed to register notify handler\n");
-               goto err;
+       if (acpi_has_method(bridge->handle, "_EJ0")) {
+               dbg("found ejectable p2p bridge\n");
+               bridge->flags |= BRIDGE_HAS_EJ0;
+       }
+       if (context->handler_for_func) {
+               /* Notify handler already installed. */
+               bridge->func = context->func;
+               get_bridge(context->func->slot->bridge);
+               return;
        }
 
-       if (!acpi_has_method(bridge->handle, "_EJ0"))
+       /* install notify handler for P2P bridges */
+       status = acpi_install_notify_handler(bridge->handle, ACPI_SYSTEM_NOTIFY,
+                                            handle_hotplug_event, NULL);
+       if (ACPI_SUCCESS(status))
                return;
 
-       dbg("found ejectable p2p bridge\n");
-       bridge->flags |= BRIDGE_HAS_EJ0;
-       if (context->func) {
-               get_bridge(context->func->slot->bridge);
-               bridge->func = context->func;
-               handle = context->handle;
-               WARN_ON(bridge->handle != handle);
-               status = acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
-                                                   handle_hotplug_event_func);
-               if (ACPI_FAILURE(status))
-                       acpi_handle_err(handle,
-                                       "failed to remove notify handler\n");
-       }
-       return;
+       acpi_handle_err(bridge->handle, "failed to register notify handler\n");
 
  err:
        cleanup_bridge(bridge);