| Thierry FOURNIER | 3c65b7a | 2017-08-31 20:35:18 +0200 | [diff] [blame] | 1 | #ifndef __XREF_H__ |
| 2 | #define __XREF_H__ |
| 3 | |
| 4 | /* xref is used to create relation between two elements. |
| 5 | * Once an element is released, it breaks the relation. If the |
| 6 | * relation is already broken, it frees the xref struct. |
| 7 | * The pointer between two elements is sort of a refcount with |
| 8 | * max value 1. The relation is only between two elements. |
| 9 | * The pointer and the type of elements a and b are conventional. |
| 10 | */ |
| 11 | |
| 12 | struct xref { |
| 13 | struct xref *peer; |
| 14 | }; |
| 15 | |
| 16 | static inline void xref_create(struct xref *xref_a, struct xref *xref_b) |
| 17 | { |
| 18 | xref_a->peer = xref_b; |
| 19 | xref_b->peer = xref_a; |
| 20 | } |
| 21 | |
| 22 | static inline struct xref *xref_get_peer(struct xref *xref) |
| 23 | { |
| 24 | if (!xref->peer) |
| 25 | return NULL; |
| 26 | return xref->peer; |
| 27 | } |
| 28 | |
| 29 | static inline void xref_disconnect(struct xref *xref) |
| 30 | { |
| 31 | if (!xref->peer) |
| 32 | return; |
| 33 | |
| 34 | xref->peer->peer = NULL; |
| 35 | xref->peer = NULL; |
| 36 | } |
| 37 | |
| 38 | #endif /* __XREF_H__ */ |