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Date:   Thu, 16 May 2019 15:59:58 +0800
From:   Yuyang Du <>
Cc:,,,,,,, Yuyang Du <>
Subject: [PATCH v2 00/17] Support for read-write lock deadlock detection

Hi Peter and Ingo,

Historically, the read-write lock (recursive-read locks included) is not
well supported in lockdep. This patchset attempts to solve this problem
sound and complete.

The bulk of the algorithm is in patch #10, which is actually not complex at
all. Hopefully, it simply works.

Now that we have read-write locks suppported, we have all the 262 cases
passed, though I have to flip some cases which, I think, are wrong.

P.S. To Boqun, I haven't got time to read your patchset except that I did
carefully read your design doc and learnt from it a lot. It is helpful.
Please give this patchset at least a look.

Change from v1:

 - As Peter pointed out the assumption that a lock class cannot ever be read
   and recursive read does not hold. The value of LOCK_TYPE_RECURSIVE is
   changed to 3 from 2, which maintains that if type1 and type2 are exclusive
   then type1 & type2 == 0. And since it is legal for a task can have a read
   and then a recursive read lock, we allow this in deadlock check.

 - Some typo fixes and rewording in comments or changelog.



Yuyang Du (17):
  locking/lockdep: Add lock type enum to explicitly specify read or
    write locks
  locking/lockdep: Add read-write type for dependency
  locking/lockdep: Add helper functions to operate on the searched path
  locking/lockdep: Update direct dependency's read-write type if it
  locking/lockdep: Rename deadlock check functions
  locking/lockdep: Adjust BFS algorithm to support multiple matches
  locking/lockdep: Introduce mark_lock_unaccessed()
  locking/lockdep: Introduce chain_hlocks_type for held lock's
    read-write type
  locking/lockdep: Hash held lock's read-write type into chain key
  locking/lockdep: Support read-write lock's deadlock detection
  locking/lockdep: Adjust lockdep selftest cases
  locking/lockdep: Remove useless lock type assignment
  locking/lockdep: Add nest lock type
  locking/lockdep: Support recursive read locks
  locking/lockdep: Adjust selftest case for recursive read lock
  locking/lockdep: Add more lockdep selftest cases
  locking/lockdep: Remove irq-safe to irq-unsafe read check

 include/linux/lockdep.h            |   57 +-
 include/linux/rcupdate.h           |    2 +-
 kernel/locking/lockdep.c           |  464 +++++++++++----
 kernel/locking/lockdep_internals.h |    4 +
 lib/locking-selftest.c             | 1099 +++++++++++++++++++++++++++++++++++-
 5 files changed, 1489 insertions(+), 137 deletions(-)


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