Re: [Xen-devel] [PATCH 1/2] smp: convert the cpu maps lock into a rw lock

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.02.2020 12:32, Roger Pau Monne wrote:
>  void __init register_cpu_notifier(struct notifier_block *nb)
>  {
> -    if ( !spin_trylock(&cpu_add_remove_lock) )
> +    if ( !write_trylock(&cpu_add_remove_lock) )
>          BUG(); /* Should never fail as we are called only during boot. */
>      notifier_chain_register(&cpu_chain, nb);
> -    spin_unlock(&cpu_add_remove_lock);
> +    write_unlock(&cpu_add_remove_lock);
>  }

So why a write lock here?

Jan

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