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authorJason A. Donenfeld <Jason@zx2c4.com>2022-02-13 22:48:04 +0100
committerJason A. Donenfeld <Jason@zx2c4.com>2022-02-21 21:14:21 +0100
commit3191dd5a1179ef0fad5a050a1702ae98b6251e8f (patch)
treee8c1a5fde507905e32020ba845136982f7643d92 /kernel/cpu.c
parentrandom: pull add_hwgenerator_randomness() declaration into random.h (diff)
downloadlinux-3191dd5a1179ef0fad5a050a1702ae98b6251e8f.tar.xz
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random: clear fast pool, crng, and batches in cpuhp bring up
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>
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 407a2568f35e..238cba15449f 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,