From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
tglx@linutronix.de, Ingo Molnar <mingo@kernel.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] random: Remove preempt disabled region
Date: Sun, 22 Jul 2018 10:52:06 -0400 [thread overview]
Message-ID: <20180722145206.GA6685@thunk.org> (raw)
In-Reply-To: <20180711143721.18378-1-bigeasy@linutronix.de>
On Wed, Jul 11, 2018 at 04:37:21PM +0200, Sebastian Andrzej Siewior wrote:
> From: Ingo Molnar <mingo@elte.hu>
>
> 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>
Applied, thanks.
- Ted
prev parent reply other threads:[~2018-07-22 15:24 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 14:37 [PATCH] random: Remove preempt disabled region Sebastian Andrzej Siewior
2018-07-22 14:52 ` Theodore Y. Ts'o [this message]
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