49 lines
1.7 KiB
Diff
49 lines
1.7 KiB
Diff
From: Ingo Molnar <mingo@elte.hu>
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Date: Fri, 3 Jul 2009 08:29:30 -0500
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Subject: [PATCH] random: Remove preempt disabled region
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.7-rt5.tar.xz
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No need to keep preemption disabled across the whole function.
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mix_pool_bytes() uses a spin_lock() to protect the pool and there are
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other places like write_pool() whhich invoke mix_pool_bytes() without
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disabling preemption.
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credit_entropy_bits() is invoked from other places like
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add_hwgenerator_randomness() without disabling preemption.
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Before commit 95b709b6be49 ("random: drop trickle mode") the function
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used __this_cpu_inc_return() which would require disabled preemption.
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The preempt_disable() section was added in commit 43d5d3018c37 ("[PATCH]
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random driver preempt robustness", history tree). It was claimed that
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the code relied on "vt_ioctl() being called under BKL".
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Cc: "Theodore Ts'o" <tytso@mit.edu>
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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[bigeasy: enhance the commit message]
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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drivers/char/random.c | 4 ----
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1 file changed, 4 deletions(-)
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--- a/drivers/char/random.c
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+++ b/drivers/char/random.c
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@@ -1122,8 +1122,6 @@ static void add_timer_randomness(struct
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} sample;
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long delta, delta2, delta3;
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- preempt_disable();
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-
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sample.jiffies = jiffies;
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sample.cycles = random_get_entropy();
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sample.num = num;
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@@ -1161,8 +1159,6 @@ static void add_timer_randomness(struct
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* and limit entropy entimate to 12 bits.
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*/
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credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
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-
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- preempt_enable();
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}
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void add_input_randomness(unsigned int type, unsigned int code,
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