linux-kernel - Re: [PATCH 25/27] locking/lockdep: Add support for dynamic keys

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Date:   Mon, 3 Dec 2018 18:31:32 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     mingo@...hat.com, tj@...nel.org, johannes.berg@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 25/27] locking/lockdep: Add support for dynamic keys

On Mon, Dec 03, 2018 at 09:07:00AM -0800, Bart Van Assche wrote:
> How about adding this as an additional patch before patch 25/27?

Excellent, thanks!

> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 9a7cca6dc3d4..ce05b9b419f4 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -725,6 +725,15 @@ static bool assign_lock_key(struct lockdep_map *lock)
>  {
>  	unsigned long can_addr, addr = (unsigned long)lock;
>  
> +	/*
> +	 * lockdep_free_key_range() assumes that struct lock_class_key
> +	 * objects do not overlap. Since we use the address of lock
> +	 * objects as class key for static objects, check whether the
> +	 * size of lock_class_key objects does not exceed the size of
> +	 * the smallest lock object.
> +	 */
> +	BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
> +
>  	if (__is_kernel_percpu_address(addr, &can_addr))
>  		lock->key = (void *)can_addr;
>  	else if (__is_module_percpu_address(addr, &can_addr))
> 
> Thanks,
> 
> Bart.