From d864b8ea6468cf1dce614a58eec92a23d8e07fec Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 26 Apr 2022 12:22:44 -0700 Subject: cxl/acpi: Add root device lockdep validation The CXL "root" device, ACPI0017, is an attach point for coordinating platform level CXL resources and is the parent device for a CXL port topology tree. As such it has distinct locking rules relative to other CXL subsystem objects, but because it is an ACPI device the lock class is established well before it is given to the cxl_acpi driver. However, the lockdep API does support changing the lock class "live" for situations like this. Add a device_lock_set_class() helper that a driver can use in ->probe() to set a custom lock class, and device_lock_reset_class() to return to the default "no validate" class before the custom lock class key goes out of scope after ->remove(). Note the helpers are all macros to support dead code elimination in the CONFIG_PROVE_LOCKING=n case, however device_set_lock_class() still needs #ifdef CONFIG_PROVE_LOCKING since lockdep_match_class() explicitly does not have a helper in the CONFIG_PROVE_LOCKING=n case (see comment in lockdep.h). The lockdep API needs 2 small tweaks to prevent "unused" warnings for the @key argument to lock_set_class(), and a new lock_set_novalidate_class() is added to supplement lockdep_set_novalidate_class() in the cases where the lock class is converted while the lock is held. Suggested-by: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: Alison Schofield Cc: Vishal Verma Cc: Ben Widawsky Cc: Jonathan Cameron Reviewed-by: Greg Kroah-Hartman Reviewed-by: Ira Weiny Link: https://lore.kernel.org/r/165100081305.1528964.11138612430659737238.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams --- include/linux/device.h | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 93459724dcde..833b0b3b0193 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -850,6 +850,49 @@ static inline bool device_supports_offline(struct device *dev) return dev->bus && dev->bus->offline && dev->bus->online; } +#define __device_lock_set_class(dev, name, key) \ +do { \ + struct device *__d2 __maybe_unused = dev; \ + lock_set_class(&__d2->mutex.dep_map, name, key, 0, _THIS_IP_); \ +} while (0) + +/** + * device_lock_set_class - Specify a temporary lock class while a device + * is attached to a driver + * @dev: device to modify + * @key: lock class key data + * + * This must be called with the device_lock() already held, for example + * from driver ->probe(). Take care to only override the default + * lockdep_no_validate class. + */ +#ifdef CONFIG_LOCKDEP +#define device_lock_set_class(dev, key) \ +do { \ + struct device *__d = dev; \ + dev_WARN_ONCE(__d, !lockdep_match_class(&__d->mutex, \ + &__lockdep_no_validate__), \ + "overriding existing custom lock class\n"); \ + __device_lock_set_class(__d, #key, key); \ +} while (0) +#else +#define device_lock_set_class(dev, key) __device_lock_set_class(dev, #key, key) +#endif + +/** + * device_lock_reset_class - Return a device to the default lockdep novalidate state + * @dev: device to modify + * + * This must be called with the device_lock() already held, for example + * from driver ->remove(). + */ +#define device_lock_reset_class(dev) \ +do { \ + struct device *__d __maybe_unused = dev; \ + lock_set_novalidate_class(&__d->mutex.dep_map, "&dev->mutex", \ + _THIS_IP_); \ +} while (0) + void lock_device_hotplug(void); void unlock_device_hotplug(void); int lock_device_hotplug_sysfs(void); -- cgit v1.2.3-59-g8ed1b