worked until prandom_u32() was switched to the real random generator, which
takes a spinlock for extraction, which does not work on RT when invoked
from atomic contexts. lockdep has no requirement for real random numbers
and it turns out sched_clock() is good enough to create the cookie. That
works everywhere and is faster.
-----BEGIN PGP SIGNATURE-----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=iuyB
-----END PGP SIGNATURE-----
Merge tag 'locking-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull lockdep fix from Thomas Gleixner:
"A RT fix for lockdep.
lockdep invokes prandom_u32() to create cookies. This worked until
prandom_u32() was switched to the real random generator, which takes a
spinlock for extraction, which does not work on RT when invoked from
atomic contexts.
lockdep has no requirement for real random numbers and it turns out
sched_clock() is good enough to create the cookie. That works
everywhere and is faster"
* tag 'locking-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Use sched_clock() for random numbers
4afb65156a