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| author |   Ingo Molnar <mingo@elte.hu> | 2018-07-22 10:51:50 -0400 |
|---|---|---|
| committer |   Theodore Ts'o <tytso@mit.edu> | 2018-07-24 15:44:32 -0400 |
| commit | b34fbaa9289328c7aec67d2b8b8b7d02bc61c67d (patch) | |
| tree | 856e8498c1293498a443b2007759cd36f54a5df6 /drivers/char/random.c | |
| parent | random: add a config option to trust the CPU's hwrng (diff) | |
| download | linux-dev-b34fbaa9289328c7aec67d2b8b8b7d02bc61c67d.tar.xz linux-dev-b34fbaa9289328c7aec67d2b8b8b7d02bc61c67d.zip | |
random: remove preempt disabled region
No need to keep preemption disabled across the whole function.
mix_pool_bytes() uses a spin_lock() to protect the pool and there are
other places like write_pool() whhich invoke mix_pool_bytes() without
disabling preemption.
credit_entropy_bits() is invoked from other places like
add_hwgenerator_randomness() without disabling preemption.
Before commit 95b709b6be49 ("random: drop trickle mode") the function
used __this_cpu_inc_return() which would require disabled preemption.
The preempt_disable() section was added in commit 43d5d3018c37 ("[PATCH]
random driver preempt robustness", history tree). It was claimed that
the code relied on "vt_ioctl() being called under BKL".
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: enhance the commit message]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index f4013b8a711b..561082d46a82 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1131,8 +1131,6 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) } sample; long delta, delta2, delta3; - preempt_disable(); - sample.jiffies = jiffies; sample.cycles = random_get_entropy(); sample.num = num; @@ -1170,8 +1168,6 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) * and limit entropy entimate to 12 bits. */ credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); - - preempt_enable(); } void add_input_randomness(unsigned int type, unsigned int code, |