On Mon, 2012-11-26 at 11:30 -0800, Greg Kroah-Hartman wrote: > On Mon, Nov 26, 2012 at 11:08:18AM -0800, Greg Kroah-Hartman wrote: > > On Mon, Nov 26, 2012 at 10:55:05AM -0800, Greg Kroah-Hartman wrote: > > > On Fri, Nov 23, 2012 at 11:09:37AM +0800, Huang Ying wrote: > > > > On Fri, 2012-11-23 at 02:35 +0000, Ben Hutchings wrote: > > > > > On Wed, 2012-11-21 at 16:39 -0800, Greg Kroah-Hartman wrote: > > > > > > 3.0-stable review patch. If anyone has any objections, please let > > > > > > me know. > > > > > > > > > > > > ------------------ > > > > > > > > > > > > From: Huang Ying <[email protected]> > > > > > > > > > > > > commit 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e upstream. > > > > > > > > > > > > If a PCI device and its parents are put into D3cold, unbinding the > > > > > > device will trigger deadlock as follow: > > > > > > > > > > > > - driver_unbind > > > > > > - device_release_driver > > > > > > - device_lock(dev) <--- previous > > > > > > lock here > > > > > > - __device_release_driver > > > > > > - pm_runtime_get_sync > > > > > > ... > > > > > > - rpm_resume(dev) > > > > > > - rpm_resume(dev->parent) > > > > > > ... > > > > > > - pci_pm_runtime_resume > > > > > > ... > > > > > > - pci_set_power_state > > > > > > - __pci_start_power_transition > > > > > > - pci_wakeup_bus(dev->parent->subordinate) > > > > > > - pci_walk_bus > > > > > > - device_lock(dev) <--- deadlock > > > > > > here > > > > > > > > > > > > > > > > > > If we do not do device_lock in pci_walk_bus, we can avoid deadlock. > > > > > > Device_lock in pci_walk_bus is introduced in commit: > > > > > > d71374dafbba7ec3f67371d3b7e9f6310a588808, corresponding email thread > > > > > > is: https://lkml.org/lkml/2006/5/26/38. The patch author Zhang > > > > > > Yanmin > > > > > > said device_lock is added to pci_walk_bus because: > > > > > > > > > > > > Some error handling functions call pci_walk_bus. For example, PCIe > > > > > > aer. Here we lock the device, so the driver wouldn't detach from > > > > > > the > > > > > > device, as the cb might call driver's callback function. > > > > > > > > > > > > So I fixed the deadlock as follows: > > > > > > > > > > > > - remove device_lock from pci_walk_bus > > > > > > - add device_lock into callback if callback will call driver's > > > > > > callback > > > > > > > > > > > > I checked pci_walk_bus users one by one, and found only PCIe aer > > > > > > needs > > > > > > device lock. > > > > > [...] > > > > > > > > > > What about eeh_report_error() in > > > > > arch/powerpc/platforms/pseries/eeh_driver.c? > > > > > > > > En... Because pci_walk_bus() invocation is removed in 3.7, so this > > > > patch is only valid for 3.7. We need another version for 3.6. > > > > > > > > > Also, is the deadlock even possible before this change in Linux 3.6? > > > > > > > > > > commit 448bd857d48e69b33ef323739dc6d8ca20d4cda7 > > > > > Author: Huang Ying <[email protected]> > > > > > Date: Sat Jun 23 10:23:51 2012 +0800 > > > > > > > > > > PCI/PM: add PCIe runtime D3cold support > > > > > > > > Before this, there will be no deadlock. So we do not need fixes before > > > > Linux 3.6. > > > > > > So the first patch mentioned here should not be included in the 3.0 and > > > 3.4 stable kernel releases? > > > > Ok, I've dropped the patch from 3.0 and 3.4-stable trees now. > > > > For 3.6, what should I do? > > Ok, for now, I've dropped this patch from 3.6-stable as well. If you > think it still needs to go there, can you provide something that works? > I see you posted one patch in this thread, but I don't understand if > that is what needs to go upstream in Linus's tree, or if it is for the > 3.6-stable tree. Please clarify.
Sorry for late. The patch I posted in this thread is for 3.6-stable tree. But I have no powerpc machine to test it, just build test it. Best Regards, Huang Ying -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
