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[RFC tip/locking v2 00/13] lockdep: Support deadlock detection for recursive read locks

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Hi Ingo and Peter,

This is V2 for recursive read lock support in lockdep. I fix several
bugs in V1 and also add irq inversion detection support for recursive
read locks.

V1: https://marc.info/?l=linux-kernel&m=150393341825453


As Peter pointed out:

	https://marc.info/?l=linux-kernel&m=150349072023540

The lockdep current has a limit support for recursive read locks, the
deadlock case as follow could not be detected:

	read_lock(A);
				lock(B);
	lock(B);
				write_lock(A);

I got some inspiration from Gautham R Shenoy:

	https://lwn.net/Articles/332801/

, and came up with this series.

The basic idea is:

*	Add recursive read locks into the graph

*	Classify dependencies into --(RR)-->, --(NR)-->, --(RN)-->,
	--(NN)-->, where R stands for recursive read lock, N stands for
	other locks(i.e. non-recursive read locks and write locks).

*	Define strong dependency paths as the paths of dependencies
	don't have two adjacent dependencies as --(*R)--> and --(R*)-->.

*	Extend __bfs() to only traverse on strong dependency paths.

*	If __bfs() finds a strong dependency circle, then a deadlock is
	reported.

The whole series is based on current master branch of Linus' tree:

	e7d0c41ecc2e ("Merge tag 'devprop-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm")

, and I also put it at:

	git://git.kernel.org/pub/scm/linux/kernel/git/boqun/linux.git arr-rfc-v2

The whole series consists of 13 patches:

1.	Do a clean up on the return value of __bfs() and its friends.

2.	Make __bfs() able to visit every dependency until a match is
	found. The old version of __bfs() could only visit each lock
	class once, and this is insufficient if we are going to add
	recursive read locks into the dependency graph.

3.	Make lock state LOCK_*_READ stand for recursive read lock only
	and LOCK_* stand for write lock and non-recursive read lock.

4-5	Extend __bfs() to be able to traverse the stong dependency
	patchs after recursive read locks added into the graph.

6-8	Adjust check_redundant(), check_noncircular() and
	check_irq_usage() with recursive read locks into consideration.

9.	Finally add recursive read locks into the dependency graph.

10-11	Adjust lock cache chain key generation with recursive read locks
	into consideration, and provide a test case.

12-13	Add more test cases.

I did pass all the lockdep selftest cases(including those I introduce),
and now run it on one of my box, haven't shot my feet yet.

Test and comments are welcome!

Regards,
Boqun

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[RFC tip/locking v2 00/13] lockdep: Support deadlock detection for recursive read locks Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:30 +0200
  [RFC tip/locking v2 01/13] lockdep: Demagic the return value of BFS Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:30 +0200
  [RFC tip/locking v2 08/13] lockdep: Fix recursive read lock related safe->unsafe detection Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 12/13] lockdep/selftest: Unleash irq_read_recursion2 and add more Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 07/13] lockdep: Support deadlock detection for recursive read in check_noncircular() Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 13/13] lockdep/selftest: Add more recursive read related test cases Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 03/13] lockdep: Change the meanings of LOCK_{USED_IN, ENABLED}_*_{READ} Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 04/13] lockdep: Introduce lock_list::dep Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 05/13] lockdep: Extend __bfs() to work with multiple kinds of dependencies Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 09/13] lockdep: Add recursive read locks into dependency graph Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 11/13] lockdep: Take read/write status in consideration when generate chainkey Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 02/13] lockdep: Make __bfs() visit every dependency rather than every class until a match Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 06/13] lockdep: Adjust check_redundant() for recursive read change Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  [RFC tip/locking v2 10/13] lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:40 +0200
  Re: [RFC tip/locking v2 00/13] lockdep: Support deadlock detection  for recursive read locks Boqun Feng <boqun.feng@gmail.com> - 2017-09-06 10:50 +0200

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