From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: linux-kernel@vger.kernel.org,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
John Ogness <john.ogness@linutronix.de>,
Mike Galbraith <efault@gmx.de>, Petr Mladek <pmladek@suse.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Theodore Ts'o <tytso@mit.edu>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v4] lib/vsprintf: defer filling siphash key on RT
Date: Mon, 1 Aug 2022 14:46:35 +0200 [thread overview]
Message-ID: <YufLK6hio/v1gfmq@linutronix.de> (raw)
In-Reply-To: <20220801123945.43081-1-Jason@zx2c4.com>
On 2022-08-01 14:39:46 [+0200], Jason A. Donenfeld wrote:
> On RT, we can't call get_random_bytes() from inside of the raw locks
> that callers of vsprintf might take, because get_random_bytes() takes
> normal spinlocks. So on those RT systems, defer the siphash key
> generation to a worker.
>
> Also, avoid using a static_branch, as this isn't the fast path.
> Using static_branch_likely() to signal that ptr_key has been filled is a
> bit much given that it is not a fast path.
>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Reported-by: Mike Galbraith <efault@gmx.de>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> Sebastian - feel free to take this and tweak it as needed. Sending this
> mostly as something illustrative of what the "simpler" thing would be
> that I had in mind. -Jason
Can have the same behaviour regardless of CONFIG_PREEMPT_RT? Here
lockdep _may_ yell with !RT because it is broken for RT.
If we agree that we drop the first %p print here, can we do this on
both (regardless of CONFIG_PREEMPT_RT)?
Sebastian
next prev parent reply other threads:[~2022-08-01 12:52 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-29 15:47 [PATCH 0/2 v2] Init the hashed pointer from a worker Sebastian Andrzej Siewior
2022-07-29 15:47 ` [PATCH 1/2 v2] lib/vsprintf: Remove static_branch_likely() from __ptr_to_hashval() Sebastian Andrzej Siewior
2022-08-01 12:11 ` Jason A. Donenfeld
2022-08-01 12:41 ` Sebastian Andrzej Siewior
2022-08-01 12:13 ` Jason A. Donenfeld
2022-08-01 12:42 ` Sebastian Andrzej Siewior
2022-07-29 15:47 ` [PATCH 2/2 v2] lib/vsprintf: Initialize vsprintf's pointer hash once the random core is ready Sebastian Andrzej Siewior
2022-07-29 23:29 ` Jason A. Donenfeld
2022-08-01 7:32 ` Sebastian Andrzej Siewior
2022-08-01 9:34 ` [PATCH 2/2 v3] " Sebastian Andrzej Siewior
2022-08-01 12:36 ` Jason A. Donenfeld
2022-08-01 12:39 ` [PATCH v4] lib/vsprintf: defer filling siphash key on RT Jason A. Donenfeld
2022-08-01 12:46 ` Sebastian Andrzej Siewior [this message]
2022-08-01 13:36 ` Jason A. Donenfeld
2022-08-01 13:44 ` Jason A. Donenfeld
2022-08-01 14:25 ` Sebastian Andrzej Siewior
2022-08-01 14:30 ` Jason A. Donenfeld
2022-08-01 13:47 ` Sebastian Andrzej Siewior
2022-08-01 13:55 ` Jason A. Donenfeld
2022-08-01 14:12 ` [PATCH v5] " Jason A. Donenfeld
2022-08-01 14:26 ` Sebastian Andrzej Siewior
2022-08-01 12:41 ` [PATCH 2/2 v3] lib/vsprintf: Initialize vsprintf's pointer hash once the random core is ready Sebastian Andrzej Siewior
2022-09-20 15:01 ` Jason A. Donenfeld
2022-09-23 10:36 ` Petr Mladek
2022-09-23 15:28 ` Sebastian Andrzej Siewior
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