| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | |
| 3 | #ifndef DEFERRED_FREE_HELPER_H |
| 4 | #define DEFERRED_FREE_HELPER_H |
| 5 | |
| 6 | /** |
| 7 | * df_reason - enum for reason why item was freed |
| 8 | * |
| 9 | * This provides a reason for why the free function was called |
| 10 | * on the item. This is useful when deferred_free is used in |
| 11 | * combination with a pagepool, so under pressure the page can |
| 12 | * be immediately freed. |
| 13 | * |
| 14 | * DF_NORMAL: Normal deferred free |
| 15 | * |
| 16 | * DF_UNDER_PRESSURE: Free was called because the system |
| 17 | * is under memory pressure. Usually |
| 18 | * from a shrinker. Avoid allocating |
| 19 | * memory in the free call, as it may |
| 20 | * fail. |
| 21 | */ |
| 22 | enum df_reason { |
| 23 | DF_NORMAL, |
| 24 | DF_UNDER_PRESSURE, |
| 25 | }; |
| 26 | |
| 27 | /** |
| 28 | * deferred_freelist_item - item structure for deferred freelist |
| 29 | * |
| 30 | * This is to be added to the structure for whatever you want to |
| 31 | * defer freeing on. |
| 32 | * |
| 33 | * @nr_pages: number of pages used by item to be freed |
| 34 | * @free: function pointer to be called when freeing the item |
| 35 | * @list: list entry for the deferred list |
| 36 | */ |
| 37 | struct deferred_freelist_item { |
| 38 | size_t nr_pages; |
| 39 | void (*free)(struct deferred_freelist_item *i, |
| 40 | enum df_reason reason); |
| 41 | struct list_head list; |
| 42 | }; |
| 43 | |
| 44 | /** |
| 45 | * deferred_free - call to add item to the deferred free list |
| 46 | * |
| 47 | * @item: Pointer to deferred_freelist_item field of a structure |
| 48 | * @free: Function pointer to the free call |
| 49 | * @nr_pages: number of pages to be freed |
| 50 | */ |
| 51 | void deferred_free(struct deferred_freelist_item *item, |
| 52 | void (*free)(struct deferred_freelist_item *i, |
| 53 | enum df_reason reason), |
| 54 | size_t nr_pages); |
| 55 | #endif |