Re: [PATCH kernel 1/9] rcu: Define notrace version of list_for_each_entry_rcu

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Sep 15, 2015 at 08:49:31PM +1000, Alexey Kardashevskiy wrote:
> This defines list_for_each_entry_rcu_notrace and list_entry_rcu_notrace
> which use rcu_dereference_raw_notrace instead of rcu_dereference_raw.
> This allows using list_for_each_entry_rcu_notrace in real mode (MMU is off).
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  include/linux/rculist.h | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index 17c6b1f..439c4d7 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -253,6 +253,25 @@ static inline void list_splice_init_rcu(struct list_head *list,
>  })
>  
>  /**
> + * list_entry_rcu_notrace - get the struct for this entry
> + * @ptr:        the &struct list_head pointer.
> + * @type:       the type of the struct this is embedded in.
> + * @member:     the name of the list_struct within the struct.
> + *
> + * This primitive may safely run concurrently with the _rcu list-mutation
> + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
> + *
> + * This is the same as list_entry_rcu() except that it does
> + * not do any RCU debugging or tracing.
> + */
> +#define list_entry_rcu_notrace(ptr, type, member) \
> +({ \
> +	typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
> +	container_of((typeof(ptr))rcu_dereference_raw_notrace(__ptr), \
> +			type, member); \
> +})
> +
> +/**
>   * Where are list_empty_rcu() and list_first_entry_rcu()?
>   *
>   * Implementing those functions following their counterparts list_empty() and
> @@ -308,6 +327,25 @@ static inline void list_splice_init_rcu(struct list_head *list,
>  		pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
>  
>  /**
> + * list_for_each_entry_rcu_notrace - iterate over rcu list of given type
> + * @pos:	the type * to use as a loop cursor.
> + * @head:	the head for your list.
> + * @member:	the name of the list_struct within the struct.
> + *
> + * This list-traversal primitive may safely run concurrently with
> + * the _rcu list-mutation primitives such as list_add_rcu()
> + * as long as the traversal is guarded by rcu_read_lock().
> + *
> + * This is the same as list_for_each_entry_rcu() except that it does
> + * not do any RCU debugging or tracing.
> + */
> +#define list_for_each_entry_rcu_notrace(pos, head, member) \
> +	for (pos = list_entry_rcu_notrace((head)->next, typeof(*pos), member); \
> +		&pos->member != (head); \
> +		pos = list_entry_rcu_notrace(pos->member.next, typeof(*pos), \
> +				member))
> +
> +/**
>   * list_for_each_entry_continue_rcu - continue iteration over list of given type
>   * @pos:	the type * to use as a loop cursor.
>   * @head:	the head for your list.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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