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Date: Thu, 10 Feb 2022 17:24:45 +0100 From: Sebastian Andrzej Siewior <bigeasy@...utronix.de> To: "Jason A. Donenfeld" <Jason@...c4.com> Cc: linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, Theodore Ts'o <tytso@....edu>, Sultan Alsawaf <sultan@...neltoast.com>, Jonathan Neuschäfer <j.neuschaefer@....net>, Eric Biggers <ebiggers@...nel.org>, Andy Lutomirski <luto@...nel.org> Subject: Re: [PATCH v4 1/2] random: remove batched entropy locking On 2022-02-09 13:56:43 [+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@...nel.org> > Reported-by: Jonathan Neuschäfer <j.neuschaefer@....net> > Tested-by: Jonathan Neuschäfer <j.neuschaefer@....net> > Link: https://lore.kernel.org/lkml/YfMa0QgsjCVdRAvJ@latitude/ > Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de> > Cc: Sultan Alsawaf <sultan@...neltoast.com> > Signed-off-by: Jason A. Donenfeld <Jason@...c4.com> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de> Sebastian
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