This is w.r.t some ACPI changes, to fix a deadlock when ejecting a cpu. In http://bugzilla.kernel.org/show_bug.cgi?id=9772#c31 Len raises some concerns about a theoretical race. In the current code path we could return to the userspace without doing the actual eject of the device. This deferring of device eject and device unregistering was done to fix a deadlock at cpu eject time. IMO, we could do with only deferring the device unregistration part to the thread. So before we return to the userspace we make sure that we execute the _PS3 and _EJ0 objects of the device being removed. So the device is physically removed when the write to the sysfile completes. patch on top of acpi-test. -- VMware, Inc. is providing the following patch to you under the terms of the GPL version 2 and no later version. This patch is provided as is, with no warranties or support. VMware disclaims all liability in connection with the use/inability to use this patch. Any use of the attached is considered acceptance of the above. Signed-off-by: Alok N Kataria <akataria@xxxxxxxxxx> Cc: Zhang Rui <rui.zhang@xxxxxxxxx> Index: linux-2.6/drivers/acpi/scan.c =================================================================== --- linux-2.6.orig/drivers/acpi/scan.c 2008-06-13 10:51:16.000000000 -0700 +++ linux-2.6/drivers/acpi/scan.c 2008-06-13 11:32:14.000000000 -0700 @@ -96,14 +96,7 @@ static int acpi_bus_hot_remove_device(void *context) { - struct acpi_device *device; - acpi_handle handle = context; - struct acpi_object_list arg_list; - union acpi_object arg; - acpi_status status = AE_OK; - - if (acpi_bus_get_device(handle, &device)) - return 0; + struct acpi_device *device = context; if (!device) return 0; @@ -118,32 +111,6 @@ return -1; } - /* power off device */ - status = acpi_evaluate_object(handle, "_PS3", NULL, NULL); - if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) - ACPI_DEBUG_PRINT((ACPI_DB_WARN, - "Power-off device failed\n")); - - if (device->flags.lockable) { - arg_list.count = 1; - arg_list.pointer = &arg; - arg.type = ACPI_TYPE_INTEGER; - arg.integer.value = 0; - acpi_evaluate_object(handle, "_LCK", &arg_list, NULL); - } - - arg_list.count = 1; - arg_list.pointer = &arg; - arg.type = ACPI_TYPE_INTEGER; - arg.integer.value = 1; - - /* - * TBD: _EJD support. - */ - status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL); - if (ACPI_FAILURE(status)) - return -ENODEV; - return 0; } @@ -153,6 +120,8 @@ { int ret = count; acpi_status status; + struct acpi_object_list arg_list; + union acpi_object arg; acpi_object_type type = 0; struct acpi_device *acpi_device = to_acpi_device(d); struct task_struct *task; @@ -172,9 +141,37 @@ goto err; } - /* remove the device in another thread to fix the deadlock issue */ + /* power off device */ + status = acpi_evaluate_object(acpi_device->handle, "_PS3", NULL, NULL); + if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) + ACPI_DEBUG_PRINT((ACPI_DB_WARN, + "Power-off device failed\n")); + + if (acpi_device->flags.lockable) { + arg_list.count = 1; + arg_list.pointer = &arg; + arg.type = ACPI_TYPE_INTEGER; + arg.integer.value = 0; + acpi_evaluate_object(acpi_device->handle, + "_LCK", &arg_list, NULL); + } + + arg_list.count = 1; + arg_list.pointer = &arg; + arg.type = ACPI_TYPE_INTEGER; + arg.integer.value = 1; + + /* + * TBD: _EJD support. + */ + status = acpi_evaluate_object(acpi_device->handle, + "_EJ0", &arg_list, NULL); + if (ACPI_FAILURE(status)) + return -ENODEV; + + /* unregister the device in another thread to fix the deadlock issue */ task = kthread_run(acpi_bus_hot_remove_device, - acpi_device->handle, "acpi_hot_remove_device"); + acpi_device, "acpi_hot_remove_device"); if (IS_ERR(task)) ret = PTR_ERR(task); err: -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
