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authorPrarit Bhargava <prarit@redhat.com>2011-09-28 19:40:53 -0400
committerJesse Barnes <jbarnes@virtuousgeek.org>2011-10-14 09:05:31 -0700
commit6af8bef14d6fc9e4e52c83fd646412e9dedadd26 (patch)
treea1ddb0962fe8d5704cff9f3627322eb2fe0fa479 /drivers/pci
parent379021d5c0899fcf9410cae4ca7a59a5a94ca769 (diff)
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>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/hotplug/acpiphp_glue.c109
1 files changed, 94 insertions, 15 deletions
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 220285760b6..596172b4ae9 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)