/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef DEFERRED_FREE_HELPER_H
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#define DEFERRED_FREE_HELPER_H
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/**
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* df_reason - enum for reason why item was freed
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*
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* This provides a reason for why the free function was called
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* on the item. This is useful when deferred_free is used in
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* combination with a pagepool, so under pressure the page can
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* be immediately freed.
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*
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* DF_NORMAL: Normal deferred free
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*
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* DF_UNDER_PRESSURE: Free was called because the system
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* is under memory pressure. Usually
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* from a shrinker. Avoid allocating
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* memory in the free call, as it may
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* fail.
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*/
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enum df_reason {
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DF_NORMAL,
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DF_UNDER_PRESSURE,
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};
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/**
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* deferred_freelist_item - item structure for deferred freelist
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*
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* This is to be added to the structure for whatever you want to
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* defer freeing on.
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*
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* @nr_pages: number of pages used by item to be freed
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* @free: function pointer to be called when freeing the item
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* @list: list entry for the deferred list
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*/
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struct deferred_freelist_item {
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size_t nr_pages;
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void (*free)(struct deferred_freelist_item *i,
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enum df_reason reason);
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struct list_head list;
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};
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/**
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* deferred_free - call to add item to the deferred free list
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*
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* @item: Pointer to deferred_freelist_item field of a structure
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* @free: Function pointer to the free call
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* @nr_pages: number of pages to be freed
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*/
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void deferred_free(struct deferred_freelist_item *item,
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void (*free)(struct deferred_freelist_item *i,
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enum df_reason reason),
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size_t nr_pages);
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unsigned long get_freelist_nr_pages(void);
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#endif
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