PCI hotplug: acpiphp: Prevent deadlock on PCI-to-PCI bridge remove
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. 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@redhat.com> Cc: mjg@redhat.com Cc: bhelgaas@google.com Cc: linux-acpi@vger.kernel.org Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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Коммит
6af8bef14d
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@ -80,7 +80,8 @@ static acpi_osd_handler acpi_irq_handler;
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static void *acpi_irq_context;
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static struct workqueue_struct *kacpid_wq;
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static struct workqueue_struct *kacpi_notify_wq;
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static struct workqueue_struct *kacpi_hotplug_wq;
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struct workqueue_struct *kacpi_hotplug_wq;
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EXPORT_SYMBOL(kacpi_hotplug_wq);
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struct acpi_res_list {
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resource_size_t start;
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@ -48,6 +48,7 @@
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#include <linux/pci-acpi.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/acpi.h>
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#include "../pci.h"
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#include "acpiphp.h"
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@ -1149,15 +1150,35 @@ check_sub_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
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return AE_OK ;
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}
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/**
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* handle_hotplug_event_bridge - handle ACPI event on bridges
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* @handle: Notify()'ed acpi_handle
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* @type: Notify code
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* @context: pointer to acpiphp_bridge structure
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*
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* Handles ACPI event notification on {host,p2p} bridges.
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*/
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static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *context)
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struct acpiphp_hp_work {
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struct work_struct work;
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acpi_handle handle;
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u32 type;
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void *context;
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};
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static void alloc_acpiphp_hp_work(acpi_handle handle, u32 type,
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void *context,
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void (*func)(struct work_struct *work))
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{
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struct acpiphp_hp_work *hp_work;
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int ret;
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hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
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if (!hp_work)
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return;
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hp_work->handle = handle;
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hp_work->type = type;
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hp_work->context = context;
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INIT_WORK(&hp_work->work, func);
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ret = queue_work(kacpi_hotplug_wq, &hp_work->work);
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if (!ret)
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kfree(hp_work);
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}
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static void _handle_hotplug_event_bridge(struct work_struct *work)
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{
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struct acpiphp_bridge *bridge;
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char objname[64];
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@ -1165,11 +1186,18 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *cont
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.pointer = objname };
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struct acpi_device *device;
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int num_sub_bridges = 0;
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struct acpiphp_hp_work *hp_work;
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acpi_handle handle;
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u32 type;
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hp_work = container_of(work, struct acpiphp_hp_work, work);
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handle = hp_work->handle;
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type = hp_work->type;
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if (acpi_bus_get_device(handle, &device)) {
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/* This bridge must have just been physically inserted */
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handle_bridge_insertion(handle, type);
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return;
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goto out;
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}
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bridge = acpiphp_handle_to_bridge(handle);
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@ -1180,7 +1208,7 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *cont
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if (!bridge && !num_sub_bridges) {
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err("cannot get bridge info\n");
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return;
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goto out;
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}
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acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
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@ -1241,22 +1269,49 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type, void *cont
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warn("notify_handler: unknown event type 0x%x for %s\n", type, objname);
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break;
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}
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out:
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kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
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}
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/**
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* handle_hotplug_event_func - handle ACPI event on functions (i.e. slots)
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* handle_hotplug_event_bridge - handle ACPI event on bridges
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* @handle: Notify()'ed acpi_handle
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* @type: Notify code
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* @context: pointer to acpiphp_func structure
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* @context: pointer to acpiphp_bridge structure
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*
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* Handles ACPI event notification on slots.
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* Handles ACPI event notification on {host,p2p} bridges.
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*/
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static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context)
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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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/*
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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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* The proper way to fix this is to reorganize the code so that
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* drivers (dock, etc.) do not call acpi_os_execute(), etc.
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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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alloc_acpiphp_hp_work(handle, type, context,
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_handle_hotplug_event_bridge);
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}
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static void _handle_hotplug_event_func(struct work_struct *work)
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{
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struct acpiphp_func *func;
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char objname[64];
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struct acpi_buffer buffer = { .length = sizeof(objname),
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.pointer = objname };
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struct acpiphp_hp_work *hp_work;
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acpi_handle handle;
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u32 type;
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void *context;
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hp_work = container_of(work, struct acpiphp_hp_work, work);
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handle = hp_work->handle;
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type = hp_work->type;
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context = hp_work->context;
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acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
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@ -1291,8 +1346,32 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *contex
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warn("notify_handler: unknown event type 0x%x for %s\n", type, objname);
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break;
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}
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kfree(hp_work); /* allocated in handle_hotplug_event_func */
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}
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/**
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* handle_hotplug_event_func - handle ACPI event on functions (i.e. slots)
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* @handle: Notify()'ed acpi_handle
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* @type: Notify code
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* @context: pointer to acpiphp_func structure
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*
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* Handles ACPI event notification on slots.
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*/
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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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/*
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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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* The proper way to fix this is to reorganize the code so that
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* drivers (dock, etc.) do not call acpi_os_execute(), etc.
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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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alloc_acpiphp_hp_work(handle, type, context,
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_handle_hotplug_event_func);
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}
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static acpi_status
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find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
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@ -189,6 +189,8 @@ void acpi_os_fixed_event_count(u32 fixed_event_number);
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/*
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* Threads and Scheduling
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*/
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extern struct workqueue_struct *kacpi_hotplug_wq;
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acpi_thread_id acpi_os_get_thread_id(void);
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acpi_status
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