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

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On Wed, Sep 06, 2017 at 04:28:11PM +0800, Boqun Feng wrote:
> 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

Hmm.. should revert

	d82fed752942 ("locking/lockdep/selftests: Fix mixed read-write ABBA tests")

for testing, as it is a work around because of we had limit support for
recursive read lock before.

I put a branch with that reverted at:

 	git://git.kernel.org/pub/scm/linux/kernel/git/boqun/linux.git arr-rfc-v2a

Selftest passed for that branch, now run it for more time.

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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