From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 12 May 2017 15:46:17 +0200
Subject: random: avoid preempt_disable()ed section
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 4bed11300e24d5178829758e535cc4996490b7c8
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension
extract_crng() will use sleeping locks while in a preempt_disable()
section due to get_cpu_var().
Work around it with local_locks.
Cc: stable-rt@vger.kernel.org # where it applies to
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
drivers/char/random.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -263,6 +263,7 @@
#include <linux/syscalls.h>
#include <linux/completion.h>
#include <linux/uuid.h>
+#include <linux/locallock.h>
#include <crypto/chacha20.h>
#include <asm/processor.h>
@@ -2175,35 +2176,37 @@ struct batched_entropy {
* point prior.
*/
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
+static DEFINE_LOCAL_IRQ_LOCK(batched_entropy_u64_lock);
u64 get_random_u64(void)
{
u64 ret;
struct batched_entropy *batch;
- batch = &get_cpu_var(batched_entropy_u64);
+ batch = &get_locked_var(batched_entropy_u64_lock, batched_entropy_u64);
if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
extract_crng((u8 *)batch->entropy_u64);
batch->position = 0;
}
ret = batch->entropy_u64[batch->position++];
- put_cpu_var(batched_entropy_u64);
+ put_locked_var(batched_entropy_u64_lock, batched_entropy_u64);
return ret;
}
EXPORT_SYMBOL(get_random_u64);
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
+static DEFINE_LOCAL_IRQ_LOCK(batched_entropy_u32_lock);
u32 get_random_u32(void)
{
u32 ret;
struct batched_entropy *batch;
- batch = &get_cpu_var(batched_entropy_u32);
+ batch = &get_locked_var(batched_entropy_u32_lock, batched_entropy_u32);
if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
extract_crng((u8 *)batch->entropy_u32);
batch->position = 0;
}
ret = batch->entropy_u32[batch->position++];
- put_cpu_var(batched_entropy_u32);
+ put_locked_var(batched_entropy_u32_lock, batched_entropy_u32);
return ret;
}
EXPORT_SYMBOL(get_random_u32);