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From: Peter Zijlstra <peterz@infradead.org>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: x86@kernel.org, jpoimboe@redhat.com, jbaron@akamai.com,
	rostedt@goodmis.org, ardb@kernel.org,
	linux-kernel@vger.kernel.org, sumit.garg@linaro.org,
	oliver.sang@intel.com, jarkko@kernel.org
Subject: Re: [PATCH 2/3] static_call: Align static_call_is_init() patching condition
Date: Mon, 22 Mar 2021 17:59:08 +0100	[thread overview]
Message-ID: <YFjM3HgyZS14x0m/@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <c4e9dfdf-c83a-3314-8c55-5b2371a56ec8@rasmusvillemoes.dk>

On Fri, Mar 19, 2021 at 03:40:46PM +0100, Rasmus Villemoes wrote:
> On 19/03/2021 15.13, Peter Zijlstra wrote:
> 
> >> Dunno, probably overkill, but perhaps we could have an atomic_t (or
> >> refcount, whatever) init_ref inited to 1, with init_ref_get() doing an
> >> inc_unless_zero, and iff you get a ref, you're free to call (/patch)
> >> __init functions and access __initdata, but must do init_ref_put(), with
> >> PID1 dropping its initial ref and waiting for it to drop to 0 before
> >> doing the *free_initmem() calls.
> > 
> > I'd as soon simply add another SYSTEM state. That way we don't have to
> > worry about who else looks at RUNNING for what etc..
> 
> I don't understand. How would that solve the
> 
> PID1                           PIDX
>                                ok = system_state < INIT_MEM_GONE;
> system_state = INIT_MEM_GONE;
> free_initmem();
> system_state = RUNNING;
>                                if (ok)
>                                    poke init mem
> 
> race?

Argh, I meant to put it before SMP bringup, but then still have to run
the smp_init calls :/

N/m, you're quite right.

  parent reply	other threads:[~2021-03-22 17:01 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18 11:31 [PATCH 0/3] static_call() vs __exit fixes Peter Zijlstra
2021-03-18 11:31 ` [PATCH 1/3] static_call: Fix static_call_set_init() Peter Zijlstra
2021-03-19 12:25   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-03-18 11:31 ` [PATCH 2/3] static_call: Align static_call_is_init() patching condition Peter Zijlstra
2021-03-19 12:25   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-03-19 13:31   ` [PATCH 2/3] " Rasmus Villemoes
2021-03-19 14:13     ` Peter Zijlstra
2021-03-19 14:40       ` Rasmus Villemoes
2021-03-19 15:44         ` Rasmus Villemoes
2021-03-22 16:59         ` Peter Zijlstra [this message]
2021-03-18 11:31 ` [PATCH 3/3] static_call: Fix static_call_update() sanity check Peter Zijlstra
2021-03-18 11:42   ` Peter Zijlstra
2021-03-18 16:13   ` Josh Poimboeuf
2021-03-18 16:58     ` Peter Zijlstra
2021-03-19 12:57       ` Peter Zijlstra
2021-03-19 18:00         ` Steven Rostedt
2021-03-19 19:34           ` Peter Zijlstra
2021-03-19 20:57             ` Steven Rostedt
2021-03-22 14:50               ` Jessica Yu
2021-03-22 16:54                 ` Peter Zijlstra
2021-03-22 17:36                   ` Jessica Yu
2021-03-22 13:07           ` Jessica Yu
2021-03-22 14:06             ` Peter Zijlstra
2021-03-19 12:25   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-03-18 12:15 ` [PATCH 0/3] static_call() vs __exit fixes Sumit Garg
2021-03-18 19:38 ` Jarkko Sakkinen

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