On Wed, Feb 09, 2022 at 01:56:43PM +0100, Jason A. Donenfeld wrote: > Rather than use spinlocks to protect batched entropy, we can instead > disable interrupts locally, since we're dealing with per-cpu data, and > manage resets with a basic generation counter. At the same time, we > can't quite do this on PREEMPT_RT, where we still want spinlocks-as- > mutexes semantics. So we use a local_lock_t, which provides the right > behavior for each. Because this is a per-cpu lock, that generation > counter is still doing the necessary CPU-to-CPU communication. > > This should improve performance a bit. It will also fix the linked splat > that Jonathan received with a PROVE_RAW_LOCK_NESTING=y. > > Suggested-by: Andy Lutomirski <luto@xxxxxxxxxx> > Reported-by: Jonathan Neuschäfer <j.neuschaefer@xxxxxxx> > Tested-by: Jonathan Neuschäfer <j.neuschaefer@xxxxxxx> > Link: https://lore.kernel.org/lkml/YfMa0QgsjCVdRAvJ@latitude/ > Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Cc: Sultan Alsawaf <sultan@xxxxxxxxxxxxxxx> > Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx> > --- > drivers/char/random.c | 55 ++++++++++++++++++++++--------------------- > 1 file changed, 28 insertions(+), 27 deletions(-) Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx> - Eric
