linux-kernel - [PATCH v2 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

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Date:	Wed, 24 Oct 2012 14:05:49 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	yinghai@...nel.org, bhelgaas@...gle.com, lenb@...nel.org,
	jiang.liu@...wei.com, izumi.taku@...fujitsu.com,
	isimatu.yasuaki@...fujitsu.com, mihailm@...allels.com,
	linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

As the comments in __acpi_os_execute() said:

	We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
	because the hotplug code may call driver .remove() functions,
	which invoke flush_scheduled_work/acpi_os_wait_events_complete
	to flush these workqueues.

we should keep the hotplug code in kacpi_hotplug_wq.

But we have the following call series in kernel now:
	acpi_ev_queue_notify_request()
	|--> acpi_os_execute()
	     |--> __acpi_os_execute(type, function, context, 0)

The last parameter 0 makes the container_notify_cb() executed in
kacpi_notify_wq or kacpid_wq. So, we need to put the real hotplug code
into kacpi_hotplug_wq.

Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
---
 drivers/acpi/container.c |   17 ++++++++++++++++-
 1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
index 69e2d6b..d300e03 100644
--- a/drivers/acpi/container.c
+++ b/drivers/acpi/container.c
@@ -35,6 +35,7 @@
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 #include <acpi/container.h>
+#include <acpi/acpiosxf.h>
 
 #define PREFIX "ACPI: "
 
@@ -165,14 +166,21 @@ static int container_device_add(struct acpi_device **device, acpi_handle handle)
 	return result;
 }
 
-static void container_notify_cb(acpi_handle handle, u32 type, void *context)
+static void __container_notify_cb(struct work_struct *work)
 {
 	struct acpi_device *device = NULL;
 	int result;
 	int present;
 	acpi_status status;
+	struct acpi_hp_work *hp_work;
+	acpi_handle handle;
+	u32 type;
 	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
 
+	hp_work = container_of(work, struct acpi_hp_work, work);
+	handle = hp_work->handle;
+	type = hp_work->type;
+
 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		/* Fall through */
@@ -224,6 +232,13 @@ static void container_notify_cb(acpi_handle handle, u32 type, void *context)
 	return;
 }
 
+static void container_notify_cb(acpi_handle handle, u32 type,
+				void *context)
+{
+	alloc_acpi_hp_work(handle, type, context,
+			   __container_notify_cb);
+}
+
 static acpi_status
 container_walk_namespace_cb(acpi_handle handle,
 			    u32 lvl, void *context, void **rv)
-- 
1.7.1

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