Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1c97be67 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

list: Use WRITE_ONCE() when adding to lists and hlists 



Code that does lockless emptiness testing of non-RCU lists is relying
on the list-addition code to write the list head's ->next pointer
atomically.  This commit therefore adds WRITE_ONCE() to list-addition
pointer stores that could affect the head's ->next pointer.

Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 6cf10081

include/linux/list.h

+4 −4
Original line number Original line Diff line number Diff line
@@ -42,7 +42,7 @@ static inline void __list_add(struct list_head *new, 
	next->prev = new;

	next->prev = new;

	new->next = next;

	new->next = next;

	new->prev = prev;

	new->prev = prev;

	prev->next = new;

	WRITE_ONCE(prev->next, new);

}

}

#else

#else

extern void __list_add(struct list_head *new,

extern void __list_add(struct list_head *new,
@@ -642,7 +642,7 @@ static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) 
	n->next = first;

	n->next = first;

	if (first)

	if (first)

		first->pprev = &n->next;

		first->pprev = &n->next;

	h->first = n;

	WRITE_ONCE(h->first, n);

	n->pprev = &h->first;

	n->pprev = &h->first;

}

}
@@ -653,14 +653,14 @@ static inline void hlist_add_before(struct hlist_node *n, 
	n->pprev = next->pprev;

	n->pprev = next->pprev;

	n->next = next;

	n->next = next;

	next->pprev = &n->next;

	next->pprev = &n->next;

	*(n->pprev) = n;

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

}

}





static inline void hlist_add_behind(struct hlist_node *n,

static inline void hlist_add_behind(struct hlist_node *n,

				    struct hlist_node *prev)

				    struct hlist_node *prev)

{

{

	n->next = prev->next;

	n->next = prev->next;

	prev->next = n;

	WRITE_ONCE(prev->next, n);

	n->pprev = &prev->next;

	n->pprev = &prev->next;





	if (n->next)

	if (n->next)

lib/list_debug.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -37,7 +37,7 @@ void __list_add(struct list_head *new, 
	next->prev = new;

	next->prev = new;

	new->next = next;

	new->next = next;

	new->prev = prev;

	new->prev = prev;

	prev->next = new;

	WRITE_ONCE(prev->next, new);

}

}

EXPORT_SYMBOL(__list_add);

EXPORT_SYMBOL(__list_add);