I originally submitted a patch to workaround this by pushing all Ejection Requests and Device Checks onto the kacpi_hotplug queue. http://marc.info/?l=linux-acpi&m=131678270930105&w=2 The patch is still insufficient in that Bus Checks also need to be added. Rather than add all events, including non-PCI-hotplug events, to the hotplug queue, mjg suggested that a better approach would be to modify the acpiphp driver so only acpiphp events would be added to the kacpi_hotplug queue. It's a longer patch, but at least we maintain the benefit of having separate queues in ACPI. This, of course, is still only a workaround the problem. As Bjorn and mjg pointed out, we have to refactor a lot of this code to do the right thing but at this point it is a better to have this code working. Jesse -- Unless there are any objections from the ACPI guys, I think this patch should be pushed through linux-pci now since 95% of the changes are contained within drivers/pci/hotplug. P. ---8<--- The acpi core places all events on the kacpi_notify queue. When the acpiphp driver is loaded and a PCI card with a PCI-to-PCI bridge is removed the following call sequence occurs: cleanup_p2p_bridge() -> cleanup_bridge() -> acpi_remove_notify_handler() -> acpi_os_wait_events_complete() -> flush_workqueue(kacpi_notify_wq) which is the queue we are currently executing on and the process will hang. Move all hotplug acpiphp events onto the kacpi_hotplug workqueue. In handle_hotplug_event_bridge() and handle_hotplug_event_func() we can simply push the rest of the work onto the kacpi_hotplug queue and then avoid the deadlock. Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx> Cc: mjg@xxxxxxxxxx Cc: bhelgaas@xxxxxxxxxx Cc: jbarnes@xxxxxxxxxxxxxxxx Cc: linux-acpi@xxxxxxxxxxxxxxx --- drivers/acpi/osl.c | 3 +- drivers/pci/hotplug/acpiphp_glue.c | 109 +++++++++++++++++++++++++++++++----- include/acpi/acpiosxf.h | 2 + 3 files changed, 98 insertions(+), 16 deletions(-) diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index fa32f58..f31c5c5 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -80,7 +80,8 @@ static acpi_osd_handler acpi_irq_handler; static void *acpi_irq_context; static struct workqueue_struct *kacpid_wq; static struct workqueue_struct *kacpi_notify_wq; -static struct workqueue_struct *kacpi_hotplug_wq; +struct workqueue_struct *kacpi_hotplug_wq; +EXPORT_SYMBOL(kacpi_hotplug_wq); struct acpi_res_list { resource_size_t start; diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 2202857..596172b 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -48,6 +48,7 @@ #include <linux/pci-acpi.h> #include <linux/mutex.h> #include <linux/slab.h> +#include <linux/acpi.h> #include "../pci.h" #include "acpiphp.h" @@ -1149,15 +1150,35 @@ check_sub_bridges(acpi_handle handle, u32 lvl, void *context, void **rv) return AE_OK ; } -/** - * 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_hp_work { + struct work_struct work; + acpi_handle handle; + u32 type; + void *context; +}; + +static void alloc_acpiphp_hp_work(acpi_handle handle, u32 type, + void *context, + void (*func)(struct work_struct *work)) +{ + struct acpiphp_hp_work *hp_work; + int ret; + + hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL); + if (!hp_work) + return; + + hp_work->handle = handle; + hp_work->type = type; + hp_work->context = context; + + INIT_WORK(&hp_work->work, func); + ret = queue_work(kacpi_hotplug_wq, &hp_work->work); + if (!ret) + kfree(hp_work); +} + +static void _handle_hotplug_event_bridge(struct work_struct *work) { struct acpiphp_bridge *bridge; char objname[64]; @@ -1165,11 +1186,18 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *cont .pointer = objname }; struct acpi_device *device; int num_sub_bridges = 0; + struct acpiphp_hp_work *hp_work; + acpi_handle handle; + u32 type; + + hp_work = container_of(work, struct acpiphp_hp_work, work); + handle = hp_work->handle; + type = hp_work->type; if (acpi_bus_get_device(handle, &device)) { /* This bridge must have just been physically inserted */ handle_bridge_insertion(handle, type); - return; + goto out; } bridge = acpiphp_handle_to_bridge(handle); @@ -1180,7 +1208,7 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *cont if (!bridge && !num_sub_bridges) { err("cannot get bridge info\n"); - return; + goto out; } acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer); @@ -1241,22 +1269,49 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *cont warn("notify_handler: unknown event type 0x%x for %s\n", type, objname); break; } + +out: + kfree(hp_work); /* allocated in handle_hotplug_event_bridge */ } /** - * handle_hotplug_event_func - handle ACPI event on functions (i.e. slots) + * handle_hotplug_event_bridge - handle ACPI event on bridges * @handle: Notify()'ed acpi_handle * @type: Notify code - * @context: pointer to acpiphp_func structure + * @context: pointer to acpiphp_bridge structure * - * Handles ACPI event notification on slots. + * Handles ACPI event notification on {host,p2p} bridges. */ -static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context) +static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, + void *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. + */ + alloc_acpiphp_hp_work(handle, type, context, + _handle_hotplug_event_bridge); +} + +static void _handle_hotplug_event_func(struct work_struct *work) { struct acpiphp_func *func; char objname[64]; struct acpi_buffer buffer = { .length = sizeof(objname), .pointer = objname }; + struct acpiphp_hp_work *hp_work; + acpi_handle handle; + u32 type; + void *context; + + hp_work = container_of(work, struct acpiphp_hp_work, work); + handle = hp_work->handle; + type = hp_work->type; + context = hp_work->context; acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer); @@ -1291,8 +1346,32 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *contex warn("notify_handler: unknown event type 0x%x for %s\n", type, objname); break; } + + kfree(hp_work); /* allocated in handle_hotplug_event_func */ } +/** + * handle_hotplug_event_func - handle ACPI event on functions (i.e. slots) + * @handle: Notify()'ed acpi_handle + * @type: Notify code + * @context: pointer to acpiphp_func structure + * + * Handles ACPI event notification on slots. + */ +static void handle_hotplug_event_func(acpi_handle handle, u32 type, + void *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. + */ + alloc_acpiphp_hp_work(handle, type, context, + _handle_hotplug_event_func); +} static acpi_status find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv) diff --git a/include/acpi/acpiosxf.h b/include/acpi/acpiosxf.h index 4543b6f..83062ed 100644 --- a/include/acpi/acpiosxf.h +++ b/include/acpi/acpiosxf.h @@ -189,6 +189,8 @@ void acpi_os_fixed_event_count(u32 fixed_event_number); /* * Threads and Scheduling */ +extern struct workqueue_struct *kacpi_hotplug_wq; + acpi_thread_id acpi_os_get_thread_id(void); acpi_status -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
