On Sat, 2008-06-14 at 04:28 +0800, Alok Kataria wrote: > 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. Acked-by: Zhang Rui <rui.zhang@xxxxxxxxx> thanks, rui > > 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
