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Date:   Thu, 13 Oct 2022 19:04:27 -0700
From:   Mark Gross <markgross@kernel.org>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     Mark Gross <markgross@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-rt-users <linux-rt-users@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Carsten Emde <C.Emde@osadl.org>,
        John Kacur <jkacur@redhat.com>,
        Danie l Wagner <dwagner@suse.de>,
        Tom Zanussi <tom.zanussi@linux.intel.com>,
        Clark Williams <williams@redhat.com>,
        Junxiao Chang <junxiao.chang@intel.com>
Subject: Re: [ANNOUNCE] 4.9.327-rt197
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 <YzcEIU17EIZ7ZIF5@linutronix.de>
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On Fri, Sep 30, 2022 at 04:58:41PM +0200, Sebastian Andrzej Siewior wrote:
> On 2022-09-23 13:09:41 [-0700], Mark Gross wrote:
> > > As this was a tricky one I request people to give a good look over.
> 
> You did good. I not so much. If you could please add the following patch
> on top, then it will compile also on !RT.
> 
> Thank you for work.
> 
> ------->8----------
> 
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Date: Fri, 30 Sep 2022 16:55:34 +0200
> Subject: [PATCH] local_lock: Provide INIT_LOCAL_LOCK().
> 
> The original code was using INIT_LOCAL_LOCK() and I tried to sneak
> around it and forgot that this code also needs to compile on !RT
> platforms.
> 
> Provide INIT_LOCAL_LOCK() to initialize properly on RT and do nothing on
> !RT. Let random.c use which is the only user so far and oes not compile
> on !RT otherwise.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  drivers/char/random.c     | 4 ++--
>  include/linux/locallock.h | 5 +++++
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index daea466812fed..86c475f70343d 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -236,7 +236,7 @@ struct crng {
>  
>  static DEFINE_PER_CPU(struct crng, crngs) = {
>  	.generation = ULONG_MAX,
> -	.lock.lock = __SPIN_LOCK_UNLOCKED(crngs.lock.lock),
> +	.lock = INIT_LOCAL_LOCK(crngs.lock),
>  };
>  
>  /* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
> @@ -515,7 +515,7 @@ struct batch_ ##type {								\
>  };										\
>  										\
>  static DEFINE_PER_CPU(struct batch_ ##type, batched_entropy_ ##type) = {	\
> -	.lock.lock = __SPIN_LOCK_UNLOCKED(batched_entropy_ ##type.lock.lock),	\
> +	.lock = INIT_LOCAL_LOCK(batched_entropy_ ##type.lock),			\
>  	.position = UINT_MAX							\
>  };										\
>  										\
> diff --git a/include/linux/locallock.h b/include/linux/locallock.h
> index 0c3ff5b23f6a1..70af9a177197e 100644
> --- a/include/linux/locallock.h
> +++ b/include/linux/locallock.h
> @@ -22,6 +22,8 @@ struct local_irq_lock {
>  	unsigned long		flags;
>  };
>  
> +#define INIT_LOCAL_LOCK(lvar)			{ .lock = __SPIN_LOCK_UNLOCKED((lvar).lock.lock) }
> +
>  #define DEFINE_LOCAL_IRQ_LOCK(lvar)					\
>  	DEFINE_PER_CPU(struct local_irq_lock, lvar) = {			\
>  		.lock = __SPIN_LOCK_UNLOCKED((lvar).lock) }
> @@ -256,6 +258,9 @@ static inline int __local_unlock_irqrestore(struct local_irq_lock *lv,
>  
>  #else /* PREEMPT_RT_BASE */
>  
> +struct local_irq_lock { };
> +#define INIT_LOCAL_LOCK(lvar)			{ }
> +
>  #define DEFINE_LOCAL_IRQ_LOCK(lvar)		__typeof__(const int) lvar
>  #define DECLARE_LOCAL_IRQ_LOCK(lvar)		extern __typeof__(const int) lvar
>  
> -- 
> 2.37.2
> 
> 
> Sebastian

Thanks!  I've applied this and starting some testing. I've also pushed the
update to v4.9-rt-next if anyone feels like giving a spin before I make the
release.

I think I'll finally get the release done in the next few days.

--mark