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random: reorder READ_ONCE() in get_random_uXX

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commit 72e5c740f6 upstream.

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>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior
2017-06-30 16:37:13 +02:00
committed by Chris
parent 3e70ca4c5e
commit f4f439ff28
1 changed files with 4 additions and 2 deletions
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6
drivers/char/random.c
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@@ -2161,7 +2161,7 @@ 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;
@@ -2177,6 +2177,7 @@ 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);
@@ -2196,7 +2197,7 @@ 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;
@@ -2206,6 +2207,7 @@ 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);