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Commit 67bdbffd authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Paul E. McKenney
Browse files

rculist: avoid __rcu annotations 



This avoids warnings from missing __rcu annotations
in the rculist implementation, making it possible to
use the same lists in both RCU and non-RCU cases.

We can add rculist annotations later, together with
lockdep support for rculist, which is missing as well,
but that may involve changing all the users.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent ca5ecddf

include/linux/rculist.h

+34 −19
Original line number Diff line number Diff line
@@ -9,6 +9,12 @@ 
#include <linux/list.h>

#include <linux/rcupdate.h>



/*

 * return the ->next pointer of a list_head in an rcu safe

 * way, we must not access it directly

 */

#define list_next_rcu(list)	(*((struct list_head __rcu **)(&(list)->next)))



/*

 * Insert a new entry between two known consecutive entries.

 *
@@ -20,7 +26,7 @@ static inline void __list_add_rcu(struct list_head *new, 
{

	new->next = next;

	new->prev = prev;

	rcu_assign_pointer(prev->next, new);

	rcu_assign_pointer(list_next_rcu(prev), new);

	next->prev = new;

}
@@ -138,7 +144,7 @@ static inline void list_replace_rcu(struct list_head *old, 
{

	new->next = old->next;

	new->prev = old->prev;

	rcu_assign_pointer(new->prev->next, new);

	rcu_assign_pointer(list_next_rcu(new->prev), new);

	new->next->prev = new;

	old->prev = LIST_POISON2;

}
@@ -193,7 +199,7 @@ static inline void list_splice_init_rcu(struct list_head *list, 
	 */



	last->next = at;

	rcu_assign_pointer(head->next, first);

	rcu_assign_pointer(list_next_rcu(head), first);

	first->prev = head;

	at->prev = last;

}
@@ -208,7 +214,9 @@ static inline void list_splice_init_rcu(struct list_head *list, 
 * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().

 */

#define list_entry_rcu(ptr, type, member) \

	container_of(rcu_dereference_raw(ptr), type, member)

	({typeof (*ptr) __rcu *__ptr = (typeof (*ptr) __rcu __force *)ptr; \

	 container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \

	})



/**

 * list_first_entry_rcu - get the first element from a list
@@ -225,9 +233,9 @@ static inline void list_splice_init_rcu(struct list_head *list, 
	list_entry_rcu((ptr)->next, type, member)



#define __list_for_each_rcu(pos, head) \

	for (pos = rcu_dereference_raw((head)->next); \

	for (pos = rcu_dereference_raw(list_next_rcu(head)); \

		pos != (head); \

		pos = rcu_dereference_raw(pos->next))

		pos = rcu_dereference_raw(list_next_rcu((pos)))



/**

 * list_for_each_entry_rcu	-	iterate over rcu list of given type
@@ -257,9 +265,9 @@ static inline void list_splice_init_rcu(struct list_head *list, 
 * as long as the traversal is guarded by rcu_read_lock().

 */

#define list_for_each_continue_rcu(pos, head) \

	for ((pos) = rcu_dereference_raw((pos)->next); \

	for ((pos) = rcu_dereference_raw(list_next_rcu(pos)); \

		prefetch((pos)->next), (pos) != (head); \

		(pos) = rcu_dereference_raw((pos)->next))

		(pos) = rcu_dereference_raw(list_next_rcu(pos)))



/**

 * list_for_each_entry_continue_rcu - continue iteration over list of given type
@@ -314,12 +322,19 @@ static inline void hlist_replace_rcu(struct hlist_node *old, 


	new->next = next;

	new->pprev = old->pprev;

	rcu_assign_pointer(*new->pprev, new);

	rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new);

	if (next)

		new->next->pprev = &new->next;

	old->pprev = LIST_POISON2;

}



/*

 * return the first or the next element in an RCU protected hlist

 */

#define hlist_first_rcu(head)	(*((struct hlist_node __rcu **)(&(head)->first)))

#define hlist_next_rcu(node)	(*((struct hlist_node __rcu **)(&(node)->next)))

#define hlist_pprev_rcu(node)	(*((struct hlist_node __rcu **)((node)->pprev)))



/**

 * hlist_add_head_rcu

 * @n: the element to add to the hash list.
@@ -346,7 +361,7 @@ static inline void hlist_add_head_rcu(struct hlist_node *n, 


	n->next = first;

	n->pprev = &h->first;

	rcu_assign_pointer(h->first, n);

	rcu_assign_pointer(hlist_first_rcu(h), n);

	if (first)

		first->pprev = &n->next;

}
@@ -374,7 +389,7 @@ static inline void hlist_add_before_rcu(struct hlist_node *n, 
{

	n->pprev = next->pprev;

	n->next = next;

	rcu_assign_pointer(*(n->pprev), n);

	rcu_assign_pointer(hlist_pprev_rcu(n), n);

	next->pprev = &n->next;

}
@@ -401,15 +416,15 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev, 
{

	n->next = prev->next;

	n->pprev = &prev->next;

	rcu_assign_pointer(prev->next, n);

	rcu_assign_pointer(hlist_next_rcu(prev), n);

	if (n->next)

		n->next->pprev = &n->next;

}



#define __hlist_for_each_rcu(pos, head)				\

	for (pos = rcu_dereference((head)->first);	\

	for (pos = rcu_dereference(hlist_first_rcu(head));	\

	     pos && ({ prefetch(pos->next); 1; });		\

	     pos = rcu_dereference(pos->next))

	     pos = rcu_dereference(hlist_next_rcu(pos)))



/**

 * hlist_for_each_entry_rcu - iterate over rcu list of given type
@@ -423,10 +438,10 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev, 
 * as long as the traversal is guarded by rcu_read_lock().

 */

#define hlist_for_each_entry_rcu(tpos, pos, head, member)		\

	for (pos = rcu_dereference_raw((head)->first);			 \

	for (pos = rcu_dereference_raw(hlist_first_rcu(head));		\

		pos && ({ prefetch(pos->next); 1; }) &&			 \

		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \

		pos = rcu_dereference_raw(pos->next))

		pos = rcu_dereference_raw(hlist_next_rcu(pos)))



/**

 * hlist_for_each_entry_rcu_bh - iterate over rcu list of given type

include/linux/rculist_nulls.h

+11 −5
Original line number Diff line number Diff line
@@ -37,6 +37,12 @@ static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n) 
	}

}



#define hlist_nulls_first_rcu(head) \

	(*((struct hlist_nulls_node __rcu __force **)&(head)->first))



#define hlist_nulls_next_rcu(node) \

	(*((struct hlist_nulls_node __rcu __force **)&(node)->next))



/**

 * hlist_nulls_del_rcu - deletes entry from hash list without re-initialization

 * @n: the element to delete from the hash list.
@@ -88,7 +94,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n, 


	n->next = first;

	n->pprev = &h->first;

	rcu_assign_pointer(h->first, n);

	rcu_assign_pointer(hlist_nulls_first_rcu(h), n);

	if (!is_a_nulls(first))

		first->pprev = &n->next;

}
@@ -101,10 +107,10 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n, 
 *

 */

#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member)			\

	for (pos = rcu_dereference_raw((head)->first);			 \

	for (pos = rcu_dereference_raw(hlist_nulls_first_rcu(head));		\

		(!is_a_nulls(pos)) &&						\

		({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \

		pos = rcu_dereference_raw(pos->next))

		pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)))



#endif

#endif

kernel/pid.c

+1 −1
Original line number Diff line number Diff line
@@ -401,7 +401,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type) 
	struct task_struct *result = NULL;

	if (pid) {

		struct hlist_node *first;

		first = rcu_dereference_check(pid->tasks[type].first,

		first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),

					      rcu_read_lock_held() ||

					      lockdep_tasklist_lock_is_held());

		if (first)