From 87a30e1f05d73a34e6d1895065541369131aaf1c Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 17 Jul 2019 18:08:26 -0700 Subject: driver-core, libnvdimm: Let device subsystems add local lockdep coverage 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 Cc: Ira Weiny Cc: Will Deacon Cc: Dave Jiang Cc: Keith Busch Cc: Peter Zijlstra Cc: Vishal Verma Cc: "Rafael J. Wysocki" Cc: Greg Kroah-Hartman Signed-off-by: Dan Williams Acked-by: Greg Kroah-Hartman Reviewed-by: Ira Weiny Link: https://lore.kernel.org/r/156341210661.292348.7014034644265455704.stgit@dwillia2-desk3.amr.corp.intel.com --- include/linux/device.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/device.h b/include/linux/device.h index 0da5c67f6be1..9237b857b598 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -909,6 +909,8 @@ struct dev_links_info { * This identifies the device type and carries type-specific * information. * @mutex: Mutex to synchronize calls to its driver. + * @lockdep_mutex: An optional debug lock that a subsystem can use as a + * peer lock to gain localized lockdep coverage of the device_lock. * @bus: Type of bus device is on. * @driver: Which driver has allocated this * @platform_data: Platform data specific to the device. @@ -991,6 +993,9 @@ struct device { core doesn't touch it */ void *driver_data; /* Driver data, set and get with dev_set_drvdata/dev_get_drvdata */ +#ifdef CONFIG_PROVE_LOCKING + struct mutex lockdep_mutex; +#endif struct mutex mutex; /* mutex to synchronize calls to * its driver. */ -- cgit v1.2.3