1 /* SPDX-License-Identifier: GPL-2.0
2 *
3 * Network memory
4 *
5 * Author: Mina Almasry <almasrymina@google.com>
6 */
7
8 #ifndef _NET_NETMEM_H
9 #define _NET_NETMEM_H
10
11 /**
12 * typedef netmem_ref - a nonexistent type marking a reference to generic
13 * network memory.
14 *
15 * A netmem_ref currently is always a reference to a struct page. This
16 * abstraction is introduced so support for new memory types can be added.
17 *
18 * Use the supplied helpers to obtain the underlying memory pointer and fields.
19 */
20 typedef unsigned long __bitwise netmem_ref;
21
22 /* This conversion fails (returns NULL) if the netmem_ref is not struct page
23 * backed.
24 *
25 * Currently struct page is the only possible netmem, and this helper never
26 * fails.
27 */
28 static inline struct page *netmem_to_page(netmem_ref netmem)
29 {
30 return (__force struct page *)netmem;
31 }
32
33 /* Converting from page to netmem is always safe, because a page can always be
34 * a netmem.
35 */
36 static inline netmem_ref page_to_netmem(struct page *page)
37 {
38 return (__force netmem_ref)page;
39 }
40
41 static inline int netmem_ref_count(netmem_ref netmem)
42 {
43 return page_ref_count(netmem_to_page(netmem));
44 }
45
46 static inline unsigned long netmem_to_pfn(netmem_ref netmem)
47 {
48 return page_to_pfn(netmem_to_page(netmem));
49 }
50
51 static inline netmem_ref netmem_compound_head(netmem_ref netmem)
52 {
53 return page_to_netmem(compound_head(netmem_to_page(netmem)));
54 }
55
56 #endif /* _NET_NETMEM_H */
57
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