From 67546762978f523749eac157903e0b01c18e083a Mon Sep 17 00:00:00 2001 From: Yijing Wang Date: Fri, 17 Jul 2015 17:16:31 +0800 Subject: PCI: Protect pci_bus->slots with pci_slot_mutex, not pci_bus_sem Rajat Jain reported a deadlock when PCIe hot-add and AER recovery happen at the same time: thread 1: pciehp_enable_slot pciehp_configure_device pci_bus_add_devices pci_bus_add_device device_attach device_lock(dev) # acquire device lock ... pciehp_probe init_slot pci_hp_register pci_create_slot down_write(pci_bus_sem) # deadlock here thread 2: aer_isr_one_error aer_process_err_device do_recovery broadcast_error_message(..., report_error_detected) pci_walk_bus(..., cb=report_error_detected, ...) down_read(&pci_bus_sem) # acquire pci_bus_sem report_error_detected(dev) # cb() device_lock(dev) # deadlock here Previously, the bus->devices and bus->slots list were protected by pci_bus_sem. In pci_create_slot(), we held it for writing so we could add to the bus->slots list. Add a new local pci_slot_mutex to protect bus->slots. Hold pci_bus_sem for reading while searching the bus->devices list. [bhelgaas: changelog] Link: http://lkml.kernel.org/r/CAA93t1qpPqbih+UB0McA_d_+2rVaNkXsinAUxYzK9+JXSS+L-g@mail.gmail.com Reported-by: Rajat Jain Tested-by: Guenter Roeck Signed-off-by: Yijing Wang Signed-off-by: Bjorn Helgaas --- include/linux/pci.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/pci.h') diff --git a/include/linux/pci.h b/include/linux/pci.h index 8a0321a8fb59..aaee493174e2 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -446,7 +446,8 @@ struct pci_bus { struct list_head children; /* list of child buses */ struct list_head devices; /* list of devices on this bus */ struct pci_dev *self; /* bridge device as seen by parent */ - struct list_head slots; /* list of slots on this bus */ + struct list_head slots; /* list of slots on this bus; + protected by pci_slot_mutex */ struct resource *resource[PCI_BRIDGE_RESOURCE_NUM]; struct list_head resources; /* address space routed to this bus */ struct resource busn_res; /* bus numbers routed to this bus */ -- cgit v1.2.3