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Subject: [PATCH v3 0/8] device-core: Enable device_lock() lockdep validation
From:   Dan Williams <dan.j.williams@intel.com>
To:     linux-cxl@vger.kernel.org
Cc:     Ira Weiny <ira.weiny@intel.com>,
        Ben Widawsky <ben.widawsky@intel.com>,
        Will Deacon <will@kernel.org>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Alison Schofield <alison.schofield@intel.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Ingo Molnar <mingo@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Waiman Long <longman@redhat.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>, nvdimm@lists.linux.dev,
        linux-kernel@vger.kernel.org
Date:   Thu, 21 Apr 2022 08:33:08 -0700
Message-ID: <165055518776.3745911.9346998911322224736.stgit@dwillia2-desk3.amr.corp.intel.com>
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Changes since v2 [1]
- Use lockdep_set_class(), lockdep_set_class_and_subclass(), and
  lock_set_class() instead of a 'lockdep_mutex' in 'struct device'.
  (Peter and Waiman)
- Include a fix identifed by this new infrastructure

[1]: https://lore.kernel.org/r/164982968798.684294.15817853329823976469.stgit@dwillia2-desk3.amr.corp.intel.com

The device_lock() uses lockdep_set_novalidate_class() because it is
taken in too many contexts that cannot be described by a single mutex
lock class. The lack of lockdep coverage leads to deadlock scenarios
landing upstream. To mitigate that problem the lockdep_mutex was added
[2].

The lockdep_mutex, however, is an unscalable hack that overlooks
advancements in the lockdep API to change a given lock's lock class [3].
With lockdep_set_class() a device subsystem can initialize a dedicated
lock class per device type at device creation time, with
lock_set_class() a device-driver can temporarily override a lockdep
class after-the-fact. Use lockdep class assignment APIs to replace the
usage of lockdep_mutex in the CXL and NVDIMM subsystems, and delete
lockdep_mutex.

[2]: commit 87a30e1f05d7 ("driver-core, libnvdimm: Let device subsystems add local lockdep coverage")
[3]: https://lore.kernel.org/r/Ylf0dewci8myLvoW@hirez.programming.kicks-ass.net

---

Dan Williams (8):
      cxl: Replace lockdep_mutex with local lock classes
      cxl/acpi: Add root device lockdep validation
      cxl: Drop cxl_device_lock()
      nvdimm: Replace lockdep_mutex with local lock classes
      ACPI: NFIT: Drop nfit_device_lock()
      nvdimm: Drop nd_device_lock()
      device-core: Kill the lockdep_mutex
      nvdimm: Fix firmware activation deadlock scenarios


 drivers/acpi/nfit/core.c        |   30 ++++++++-------
 drivers/acpi/nfit/nfit.h        |   24 ------------
 drivers/base/core.c             |    3 --
 drivers/cxl/acpi.c              |   15 ++++++++
 drivers/cxl/core/memdev.c       |    3 ++
 drivers/cxl/core/pmem.c         |   10 ++++-
 drivers/cxl/core/port.c         |   68 ++++++++++++++++------------------
 drivers/cxl/cxl.h               |   78 ---------------------------------------
 drivers/cxl/mem.c               |    4 +-
 drivers/cxl/pmem.c              |   12 +++---
 drivers/nvdimm/btt_devs.c       |   23 +++++++-----
 drivers/nvdimm/bus.c            |   38 ++++++++-----------
 drivers/nvdimm/core.c           |   14 +++----
 drivers/nvdimm/dax_devs.c       |    4 +-
 drivers/nvdimm/dimm_devs.c      |   12 ++++--
 drivers/nvdimm/namespace_devs.c |   46 ++++++++++++++---------
 drivers/nvdimm/nd-core.h        |   68 +---------------------------------
 drivers/nvdimm/pfn_devs.c       |   31 +++++++++-------
 drivers/nvdimm/pmem.c           |    2 +
 drivers/nvdimm/region.c         |    2 +
 drivers/nvdimm/region_devs.c    |   20 ++++++----
 include/linux/device.h          |   30 +++++++++++++--
 lib/Kconfig.debug               |   23 ------------
 23 files changed, 209 insertions(+), 351 deletions(-)

base-commit: ce522ba9ef7e2d9fb22a39eb3371c0c64e2a433e