diff options
| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-02-13 22:48:04 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-30 09:29:09 +0200 |
| commit | 144c1e7ecf00688ae8c7f9a8483820527505a9d7 (patch) | |
| tree | 35192257d25570b6c2fd6ac26ca72b0b8a081f70 /kernel | |
| parent | 80c1f7f8f3cd58114fedb190f744f485e54541c9 (diff) | |
random: clear fast pool, crng, and batches in cpuhp bring up
commit 3191dd5a1179ef0fad5a050a1702ae98b6251e8f upstream.
For the irq randomness fast pool, rather than having to use expensive
atomics, which were visibly the most expensive thing in the entire irq
handler, simply take care of the extreme edge case of resetting count to
zero in the cpuhp online handler, just after workqueues have been
reenabled. This simplifies the code a bit and lets us use vanilla
variables rather than atomics, and performance should be improved.
As well, very early on when the CPU comes up, while interrupts are still
disabled, we clear out the per-cpu crng and its batches, so that it
always starts with fresh randomness.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpu.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 5601216eb51b..da871eb07566 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -34,6 +34,7 @@ #include <linux/scs.h> #include <linux/percpu-rwsem.h> #include <linux/cpuset.h> +#include <linux/random.h> #include <trace/events/power.h> #define CREATE_TRACE_POINTS @@ -1659,6 +1660,11 @@ static struct cpuhp_step cpuhp_hp_states[] = { .startup.single = perf_event_init_cpu, .teardown.single = perf_event_exit_cpu, }, + [CPUHP_RANDOM_PREPARE] = { + .name = "random:prepare", + .startup.single = random_prepare_cpu, + .teardown.single = NULL, + }, [CPUHP_WORKQUEUE_PREP] = { .name = "workqueue:prepare", .startup.single = workqueue_prepare_cpu, @@ -1782,6 +1788,11 @@ static struct cpuhp_step cpuhp_hp_states[] = { .startup.single = workqueue_online_cpu, .teardown.single = workqueue_offline_cpu, }, + [CPUHP_AP_RANDOM_ONLINE] = { + .name = "random:online", + .startup.single = random_online_cpu, + .teardown.single = NULL, + }, [CPUHP_AP_RCUTREE_ONLINE] = { .name = "RCU/tree:online", .startup.single = rcutree_online_cpu, |