> -----Original Message----- > From: Rafael J. Wysocki [mailto:rjw@xxxxxxx] > Sent: Thursday, February 14, 2013 4:04 AM > To: Moore, Robert > Cc: Toshi Kani; ACPI Devel Maling List; LKML; Bjorn Helgaas; Jiang Liu; > Yinghai Lu; Yasuaki Ishimatsu; Myron Stowe; linux-pci@xxxxxxxxxxxxxxx > Subject: Re: [Update][PATCH] ACPI / hotplug: Fix concurrency issues and > memory leaks > > On Thursday, February 14, 2013 02:31:22 AM Moore, Robert wrote: > > > > > I thought about that, but actually there's no guarantee that the > > > > > handle will be valid after _EJ0 as far as I can say. So the > > > > > race condition is going to be there anyway and using struct > > > > > acpi_device just makes it easier to avoid it. > > > > > > > > In theory, yes, a stale handle could be a problem, if _EJ0 > > > > performs unload table and if ACPICA frees up its internal data > > > > structure pointed by the handle as a result. But we should not > > > > see such issue now since we do not support dynamic ACPI namespace > yet. > > > > > > I'm waiting for information from Bob about that. If we can assume > > > ACPI handles to be always valid, that will simplify things quite a > bit. > > > > If a table is unloaded, all the namespace nodes for that table are > > removed from the namespace, and thus any ACPI_HANDLE pointers go stale > and invalid. > > OK, thanks! > > To me this means that we cannot assume a handle to stay valid between a > notify handler and acpi_bus_hot_remove_device() run from a workqueue. > > Is there a mechanism in ACPICA to ensure that a handle won't become stale > while a notify handler is running for it or is the OS responsible for > ensuring that > _EJ0 won't be run in parallel with notify handlers for device objects > being ejected? > It is up to the host. Bob > Rafael > > > -- > I speak only for myself. > Rafael J. Wysocki, Intel Open Source Technology Center. ��.n��������+%������w��{.n�����{���"�)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
