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Feedback-ID: iad51458e:Fastmail
Date:   Wed, 3 Aug 2022 13:58:58 -0700
From:   Boqun Feng <boqun.feng@gmail.com>
To:     Miguel Ojeda <ojeda@kernel.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Wedson Almeida Filho <wedsonaf@google.com>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>
Subject: Re: [PATCH v8 07/31] locking/spinlock: introduce `__spin_lock_init`
Message-ID: <Yurhktr8WEpn2k9h@boqun-archlinux>
References: <20220802015052.10452-1-ojeda@kernel.org>
 <20220802015052.10452-8-ojeda@kernel.org>
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On Tue, Aug 02, 2022 at 03:49:54AM +0200, Miguel Ojeda wrote:
> From: Wedson Almeida Filho <wedsonaf@google.com>
> 
> A Rust helper (introduced in a later patch) needs to call
> `spin_lock_init` with a passed key, rather than define
> one in place.
> 
> In order to do that, this changes the `spin_lock_init` macro
> to call a new `__spin_lock_init` function which takes the key
> as an extra parameter.
> 
> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
> Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Acked-by: Boqun Feng <boqun.feng@gmail.com>

Peter, Will & Waiman, could you take a look at this patch and patch #8?

These two are needed because currently there is no way to convert a C
macro to a Rust macro, a C macro can be called as a function on Rust
side, but that's not quite for generating a static key of lockdep. As
a result, __spin_lock_init() needs to be exposed.

I think these are tiny and harmless, but looking forwards to your
insight ;-)

Regards,
Boqun

> ---
>  include/linux/spinlock.h | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
> index 5c0c5174155d..ad1c91884ed8 100644
> --- a/include/linux/spinlock.h
> +++ b/include/linux/spinlock.h
> @@ -326,12 +326,17 @@ static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
>  
>  #ifdef CONFIG_DEBUG_SPINLOCK
>  
> +static inline void __spin_lock_init(spinlock_t *lock, const char *name,
> +				    struct lock_class_key *key)
> +{
> +	__raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
> +}
> +
>  # define spin_lock_init(lock)					\
>  do {								\
>  	static struct lock_class_key __key;			\
>  								\
> -	__raw_spin_lock_init(spinlock_check(lock),		\
> -			     #lock, &__key, LD_WAIT_CONFIG);	\
> +	__spin_lock_init(lock, #lock, &__key);			\
>  } while (0)
>  
>  #else
> -- 
> 2.37.1
> 
>