xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

rcu: Add a hlist_nulls_unhashed_lockless() function

Browse Source 
This commit adds an hlist_nulls_unhashed_lockless() to allow lockless
checking for whether or note an hlist_nulls_node is hashed or not.
While in the area, this commit also adds a docbook comment to the existing
hlist_nulls_unhashed() function.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney
2019-11-09 10:45:47 -08:00
parent 46deb7449d
commit 02b99b38f3
1 changed files with 22 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
include/linux/list_nulls.h
View File

@@ -56,11 +56,33 @@ static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr)
return ((unsigned long)ptr) >> 1; return ((unsigned long)ptr) >> 1;
} }
/**
* hlist_nulls_unhashed - Has node been removed and reinitialized?
* @h: Node to be checked
*
* Not that not all removal functions will leave a node in unhashed state.
* For example, hlist_del_init_rcu() leaves the node in unhashed state,
* but hlist_nulls_del() does not.
*/
static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h) static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)
{ {
return !h->pprev; return !h->pprev;
} }
/**
* hlist_nulls_unhashed_lockless - Has node been removed and reinitialized?
* @h: Node to be checked
*
* Not that not all removal functions will leave a node in unhashed state.
* For example, hlist_del_init_rcu() leaves the node in unhashed state,
* but hlist_nulls_del() does not. Unlike hlist_nulls_unhashed(), this
* function may be used locklessly.
*/
static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h)
{
return !READ_ONCE(h->pprev);
}
static inline int hlist_nulls_empty(const struct hlist_nulls_head *h) static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)
{ {
return is_a_nulls(READ_ONCE(h->first)); return is_a_nulls(READ_ONCE(h->first));