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random: reorder READ_ONCE() in get_random_uXX 

Avoid the READ_ONCE in commit 4a072c71f4 ("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>
This commit is contained in:
Sebastian Andrzej Siewior 2017-06-30 16:37:13 +02:00 committed by Theodore Ts'o
parent eecabf5674
commit 72e5c740f6
1 changed files with 4 additions and 2 deletions
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6
drivers/char/random.c
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@ -2089,7 +2089,7 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
u64 get_random_u64(void) u64 get_random_u64(void)
{ {
u64 ret; u64 ret;
bool use_lock = READ_ONCE(crng_init) < 2; bool use_lock;
unsigned long flags = 0; unsigned long flags = 0;
struct batched_entropy *batch; struct batched_entropy *batch;
static void *previous; static void *previous;
@ -2105,6 +2105,7 @@ u64 get_random_u64(void)
warn_unseeded_randomness(&previous); warn_unseeded_randomness(&previous);
use_lock = READ_ONCE(crng_init) < 2;
batch = &get_cpu_var(batched_entropy_u64); batch = &get_cpu_var(batched_entropy_u64);
if (use_lock) if (use_lock)
read_lock_irqsave(&batched_entropy_reset_lock, flags); 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 get_random_u32(void)
{ {
u32 ret; u32 ret;
bool use_lock = READ_ONCE(crng_init) < 2; bool use_lock;
unsigned long flags = 0; unsigned long flags = 0;
struct batched_entropy *batch; struct batched_entropy *batch;
static void *previous; static void *previous;
@ -2134,6 +2135,7 @@ u32 get_random_u32(void)
warn_unseeded_randomness(&previous); warn_unseeded_randomness(&previous);
use_lock = READ_ONCE(crng_init) < 2;
batch = &get_cpu_var(batched_entropy_u32); batch = &get_cpu_var(batched_entropy_u32);
if (use_lock) if (use_lock)
read_lock_irqsave(&batched_entropy_reset_lock, flags); read_lock_irqsave(&batched_entropy_reset_lock, flags);