random: reorder READ_ONCE() in get_random_uXX

Avoid the READ_ONCE in commit 4a072c71f49b ("random: silence compiler
warnings and fix race") if we can leave the function after
arch_get_random_XXX().

Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 799d37981d9971142ebb35b6d2bee891f8aa6191..05d255e1c112fef87c4c8c6da5cb810fea1999cf 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2089,7 +2089,7 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
 u64 get_random_u64(void)
 {
        u64 ret;
-       bool use_lock = READ_ONCE(crng_init) < 2;
+       bool use_lock;
        unsigned long flags = 0;
        struct batched_entropy *batch;
        static void *previous;
@@ -2105,6 +2105,7 @@ u64 get_random_u64(void)
 
        warn_unseeded_randomness(&previous);
 
+       use_lock = READ_ONCE(crng_init) < 2;
        batch = &get_cpu_var(batched_entropy_u64);
        if (use_lock)
                read_lock_irqsave(&batched_entropy_reset_lock, flags);
@@ -2124,7 +2125,7 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
 u32 get_random_u32(void)
 {
        u32 ret;
-       bool use_lock = READ_ONCE(crng_init) < 2;
+       bool use_lock;
        unsigned long flags = 0;
        struct batched_entropy *batch;
        static void *previous;
@@ -2134,6 +2135,7 @@ u32 get_random_u32(void)
 
        warn_unseeded_randomness(&previous);
 
+       use_lock = READ_ONCE(crng_init) < 2;
        batch = &get_cpu_var(batched_entropy_u32);
        if (use_lock)
                read_lock_irqsave(&batched_entropy_reset_lock, flags);