1 files changed, 17 insertions, 16 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 36d29da31af0..e872acc1238f 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1265,29 +1265,30 @@ static void __cold entropy_timer(struct timer_list *timer)
 static void __cold try_to_generate_entropy(void)
 {
 	enum { NUM_TRIAL_SAMPLES = 8192, MAX_SAMPLES_PER_BIT = HZ / 15 };
-	struct entropy_timer_state stack;
+	u8 stack_bytes[sizeof(struct entropy_timer_state) + SMP_CACHE_BYTES - 1];
+	struct entropy_timer_state *stack = PTR_ALIGN((void *)stack_bytes, SMP_CACHE_BYTES);
 	unsigned int i, num_different = 0;
 	unsigned long last = random_get_entropy();
 	int cpu = -1;
 
 	for (i = 0; i < NUM_TRIAL_SAMPLES - 1; ++i) {
-		stack.entropy = random_get_entropy();
-		if (stack.entropy != last)
+		stack->entropy = random_get_entropy();
+		if (stack->entropy != last)
 			++num_different;
-		last = stack.entropy;
+		last = stack->entropy;
 	}
-	stack.samples_per_bit = DIV_ROUND_UP(NUM_TRIAL_SAMPLES, num_different + 1);
-	if (stack.samples_per_bit > MAX_SAMPLES_PER_BIT)
+	stack->samples_per_bit = DIV_ROUND_UP(NUM_TRIAL_SAMPLES, num_different + 1);
+	if (stack->samples_per_bit > MAX_SAMPLES_PER_BIT)
 		return;
 
-	atomic_set(&stack.samples, 0);
-	timer_setup_on_stack(&stack.timer, entropy_timer, 0);
+	atomic_set(&stack->samples, 0);
+	timer_setup_on_stack(&stack->timer, entropy_timer, 0);
 	while (!crng_ready() && !signal_pending(current)) {
 		/*
 		 * Check !timer_pending() and then ensure that any previous callback has finished
 		 * executing by checking try_to_del_timer_sync(), before queueing the next one.
 		 */
-		if (!timer_pending(&stack.timer) && try_to_del_timer_sync(&stack.timer) >= 0) {
+		if (!timer_pending(&stack->timer) && try_to_del_timer_sync(&stack->timer) >= 0) {
 			struct cpumask timer_cpus;
 			unsigned int num_cpus;
 
@@ -1314,20 +1315,20 @@ static void __cold try_to_generate_entropy(void)
 			} while (cpu == smp_processor_id() && num_cpus > 1);
 
 			/* Expiring the timer at `jiffies` means it's the next tick. */
-			stack.timer.expires = jiffies;
+			stack->timer.expires = jiffies;
 
-			add_timer_on(&stack.timer, cpu);
+			add_timer_on(&stack->timer, cpu);
 
 			preempt_enable();
 		}
-		mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
+		mix_pool_bytes(&stack->entropy, sizeof(stack->entropy));
 		schedule();
-		stack.entropy = random_get_entropy();
+		stack->entropy = random_get_entropy();
 	}
-	mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
+	mix_pool_bytes(&stack->entropy, sizeof(stack->entropy));
 
-	del_timer_sync(&stack.timer);
-	destroy_timer_on_stack(&stack.timer);
+	del_timer_sync(&stack->timer);
+	destroy_timer_on_stack(&stack->timer);
 }