Andi reported that the Intel Uncore performance monitoring suffers from the global pci_lock which protects the generic PCI config space accessors.
This lock can be removed on X86 because all architecture specific config space accessors are either serialized by a seperate lock or can be converted to have their own locking. The mmconfig based access (ECAM) does not require serialization at the config read/write level because the access is a simple byte/word/dword read from or write to the memory mapped configuration space. In that case the lock does not provide any more protection than the hardware provides already. The series converts the CE4100 PCI low level accessors to use the x86 specific pci_config_lock and implements the switch over to lockless ECAM configureation space accesors when the system is capable. Thanks, tglx --- arch/x86/Kconfig | 1 arch/x86/include/asm/pci.h | 8 --- arch/x86/include/asm/pci_x86.h | 15 +++---- arch/x86/pci/Makefile | 2 arch/x86/pci/ce4100.c | 87 ++++++++++++++++++++++------------------- arch/x86/pci/common.c | 16 +++++++ arch/x86/pci/legacy.c | 19 +++++--- arch/x86/pci/mmconfig-shared.c | 36 ++++++++++++++++ arch/x86/pci/mmconfig_32.c | 12 ----- arch/x86/pci/mmconfig_64.c | 16 +------ drivers/pci/Kconfig | 3 + drivers/pci/access.c | 16 +++++-- 12 files changed, 142 insertions(+), 89 deletions(-)