lockdep: Print proper scenario if cross deadlock detected at acquisition time
For a potential deadlock about CROSSRELEASE as follow:
P1 P2
=========== =============
lock(A)
lock(X)
lock(A)
commit(X)
A: normal lock, X: cross lock
, we could detect it at two places:
1. commit time:
We have run P1 first, and have dependency A --> X in graph, and
then we run P2, and find the deadlock.
2. acquisition time:
We have run P2 first, and have dependency X --> A, in
graph(because another P3 may run previously and is acquiring for
lock X), and then we run P1 and find the deadlock.
In current print_circular_lock_scenario(), for 1) we could print the
right scenario and note that's a deadlock related to CROSSRELEASE,
however for 2) we print the scenario as a normal lockdep deadlock.
It's better to print a proper scenario related to CROSSRELEASE to help
users find their bugs more easily, so improve this.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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