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rculist: avoid __rcu annotations

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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: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Arnd Bergmann 2010-02-25 16:55:13 +01:00 committed by Paul E. McKenney
parent ca5ecddfa8
commit 67bdbffd69
3 changed files with 46 additions and 25 deletions
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53
include/linux/rculist.h
View File

@ -9,6 +9,12 @@
#include <linux/list.h> #include <linux/list.h>
#include <linux/rcupdate.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. * 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->next = next;
new->prev = prev; new->prev = prev;
rcu_assign_pointer(prev->next, new); rcu_assign_pointer(list_next_rcu(prev), new);
next->prev = new; next->prev = new;
} }
@ -138,7 +144,7 @@ static inline void list_replace_rcu(struct list_head *old,
{ {
new->next = old->next; new->next = old->next;
new->prev = old->prev; new->prev = old->prev;
rcu_assign_pointer(new->prev->next, new); rcu_assign_pointer(list_next_rcu(new->prev), new);
new->next->prev = new; new->next->prev = new;
old->prev = LIST_POISON2; old->prev = LIST_POISON2;
} }
@ -193,7 +199,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
*/ */
last->next = at; last->next = at;
rcu_assign_pointer(head->next, first); rcu_assign_pointer(list_next_rcu(head), first);
first->prev = head; first->prev = head;
at->prev = last; 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(). * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
*/ */
#define list_entry_rcu(ptr, type, member) \ #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 * 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) list_entry_rcu((ptr)->next, type, member)
#define __list_for_each_rcu(pos, head) \ #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 != (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 * 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(). * as long as the traversal is guarded by rcu_read_lock().
*/ */
#define list_for_each_continue_rcu(pos, head) \ #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); \ 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 * 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->next = next;
new->pprev = old->pprev; new->pprev = old->pprev;
rcu_assign_pointer(*new->pprev, new); rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new);
if (next) if (next)
new->next->pprev = &new->next; new->next->pprev = &new->next;
old->pprev = LIST_POISON2; 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 * hlist_add_head_rcu
* @n: the element to add to the hash list. * @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->next = first;
n->pprev = &h->first; n->pprev = &h->first;
rcu_assign_pointer(h->first, n); rcu_assign_pointer(hlist_first_rcu(h), n);
if (first) if (first)
first->pprev = &n->next; first->pprev = &n->next;
} }
@ -374,7 +389,7 @@ static inline void hlist_add_before_rcu(struct hlist_node *n,
{ {
n->pprev = next->pprev; n->pprev = next->pprev;
n->next = next; n->next = next;
rcu_assign_pointer(*(n->pprev), n); rcu_assign_pointer(hlist_pprev_rcu(n), n);
next->pprev = &n->next; next->pprev = &n->next;
} }
@ -401,15 +416,15 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
{ {
n->next = prev->next; n->next = prev->next;
n->pprev = &prev->next; n->pprev = &prev->next;
rcu_assign_pointer(prev->next, n); rcu_assign_pointer(hlist_next_rcu(prev), n);
if (n->next) if (n->next)
n->next->pprev = &n->next; n->next->pprev = &n->next;
} }
#define __hlist_for_each_rcu(pos, head) \ #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 && ({ 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 * hlist_for_each_entry_rcu - iterate over rcu list of given type
@ -422,11 +437,11 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
* the _rcu list-mutation primitives such as hlist_add_head_rcu() * the _rcu list-mutation primitives such as hlist_add_head_rcu()
* as long as the traversal is guarded by rcu_read_lock(). * as long as the traversal is guarded by rcu_read_lock().
*/ */
#define hlist_for_each_entry_rcu(tpos, pos, head, member) \ #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; }) && \ pos && ({ prefetch(pos->next); 1; }) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 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 * hlist_for_each_entry_rcu_bh - iterate over rcu list of given type

16
include/linux/rculist_nulls.h
View File

@ -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 * hlist_nulls_del_rcu - deletes entry from hash list without re-initialization
* @n: the element to delete from the hash list. * @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->next = first;
n->pprev = &h->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)) if (!is_a_nulls(first))
first->pprev = &n->next; first->pprev = &n->next;
} }
@ -100,11 +106,11 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
* @member: the name of the hlist_nulls_node within the struct. * @member: the name of the hlist_nulls_node within the struct.
* *
*/ */
#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \ #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)) && \ (!is_a_nulls(pos)) && \
({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \ ({ 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
#endif #endif

2
kernel/pid.c
View File

@ -401,7 +401,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
struct task_struct *result = NULL; struct task_struct *result = NULL;
if (pid) { if (pid) {
struct hlist_node *first; 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() || rcu_read_lock_held() ||
lockdep_tasklist_lock_is_held()); lockdep_tasklist_lock_is_held());
if (first) if (first)