locking/lockdep: Detect chain_key collisions

Add detection for chain_key collision under CONFIG_DEBUG_LOCKDEP.
When a collision is detected the problem is reported and all lock
debugging is turned off.

Tested using liblockdep and the added tests before and after
applying the fix, confirming both that the code added for the
detection correctly reports the problem and that the fix actually
fixes it.

Tested tweaking lockdep to generate false collisions and
verified that the problem is reported and that lock debugging is
turned off.

Also tested with lockdep's test suite after applying the patch:

    [    0.000000] Good, all 253 testcases passed! |

Signed-off-by: Alfredo Alvarez Fernandez <[email protected]>
Cc: Alfredo Alvarez Fernandez <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/1455864533-7536-4-git-send-email-alfredoalvarezernandez@gmail.com
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions