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ACPI / hotplug / PCI: Unified notify handler for hotplug events
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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>
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Rafael J. Wysocki committed Jul 23, 2013
1 parent cb7b8ce commit 8783127
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Showing 2 changed files with 53 additions and 80 deletions.
1 change: 1 addition & 0 deletions drivers/pci/hotplug/acpiphp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,7 @@ struct acpiphp_context {
struct acpiphp_func *func;
struct acpiphp_bridge *bridge;
unsigned int refcount;
bool handler_for_func;
};

/*
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132 changes: 52 additions & 80 deletions drivers/pci/hotplug/acpiphp_glue.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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");
}

Expand Down Expand Up @@ -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");
}
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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
Expand All @@ -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);
}

/*
Expand Down Expand Up @@ -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);
Expand Down

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