From 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Wed, 24 Oct 2012 14:54:13 +0800 Subject: PCI/PM: Fix deadlock when unbinding device if parent in D3cold 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. Signed-off-by: Huang Ying Signed-off-by: Bjorn Helgaas Acked-by: Rafael J. Wysocki CC: stable@vger.kernel.org # v3.6+ CC: Zhang Yanmin --- drivers/pci/bus.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'drivers/pci/bus.c') diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 6241fd05bd41..a543746fb354 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -320,10 +320,7 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), } else next = dev->bus_list.next; - /* Run device routines with the device locked */ - device_lock(&dev->dev); retval = cb(dev, userdata); - device_unlock(&dev->dev); if (retval) break; } -- cgit