• Dan Williams's avatar
    driver-core, libnvdimm: Let device subsystems add local lockdep coverage · 87a30e1f
    Dan Williams authored
    For good reason, the standard device_lock() is marked
    lockdep_set_novalidate_class() because there is simply no sane way to
    describe the myriad ways the device_lock() ordered with other locks.
    However, that leaves subsystems that know their own local device_lock()
    ordering rules to find lock ordering mistakes manually. Instead,
    introduce an optional / additional lockdep-enabled lock that a subsystem
    can acquire in all the same paths that the device_lock() is acquired.
    A conversion of the NFIT driver and NVDIMM subsystem to a
    lockdep-validate device_lock() scheme is included. The
    debug_nvdimm_lock() implementation implements the correct lock-class and
    stacking order for the libnvdimm device topology hierarchy.
    Yes, this is a hack, but hopefully it is a useful hack for other
    subsystems device_lock() debug sessions. Quoting Greg:
        "Yeah, it feels a bit hacky but it's really up to a subsystem to mess up
         using it as much as anything else, so user beware :)
         I don't object to it if it makes things easier for you to debug."
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Ira Weiny <ira.weiny@intel.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Dave Jiang <dave.jiang@intel.com>
    Cc: Keith Busch <keith.busch@intel.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Vishal Verma <vishal.l.verma@intel.com>
    Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
    Link: https://lore.kernel.org/r/156341210661.292348.7014034644265455704.stgit@dwillia2-desk3.amr.corp.intel.com