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 <ying.hu...@intel.com> > > > > 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 <ying.hu...@intel.com> > 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. Best Regards, Huang Ying -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/