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10542ca0 IM |
1 | /* |
2 | * Copyright 2014 IBM Corp. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version | |
7 | * 2 of the License, or (at your option) any later version. | |
8 | */ | |
9 | ||
10 | #include <linux/module.h> | |
11 | #include <linux/rcupdate.h> | |
12 | #include <asm/errno.h> | |
13 | #include <misc/cxl.h> | |
14 | #include "cxl.h" | |
15 | ||
16 | /* protected by rcu */ | |
17 | static struct cxl_calls *cxl_calls; | |
18 | ||
19 | atomic_t cxl_use_count = ATOMIC_INIT(0); | |
20 | EXPORT_SYMBOL(cxl_use_count); | |
21 | ||
22 | #ifdef CONFIG_CXL_MODULE | |
23 | ||
24 | static inline struct cxl_calls *cxl_calls_get(void) | |
25 | { | |
26 | struct cxl_calls *calls = NULL; | |
27 | ||
28 | rcu_read_lock(); | |
29 | calls = rcu_dereference(cxl_calls); | |
30 | if (calls && !try_module_get(calls->owner)) | |
31 | calls = NULL; | |
32 | rcu_read_unlock(); | |
33 | ||
34 | return calls; | |
35 | } | |
36 | ||
37 | static inline void cxl_calls_put(struct cxl_calls *calls) | |
38 | { | |
39 | BUG_ON(calls != cxl_calls); | |
40 | ||
41 | /* we don't need to rcu this, as we hold a reference to the module */ | |
42 | module_put(cxl_calls->owner); | |
43 | } | |
44 | ||
45 | #else /* !defined CONFIG_CXL_MODULE */ | |
46 | ||
47 | static inline struct cxl_calls *cxl_calls_get(void) | |
48 | { | |
49 | return cxl_calls; | |
50 | } | |
51 | ||
52 | static inline void cxl_calls_put(struct cxl_calls *calls) { } | |
53 | ||
54 | #endif /* CONFIG_CXL_MODULE */ | |
55 | ||
56 | void cxl_slbia(struct mm_struct *mm) | |
57 | { | |
58 | struct cxl_calls *calls; | |
59 | ||
60 | calls = cxl_calls_get(); | |
61 | if (!calls) | |
62 | return; | |
63 | ||
64 | if (cxl_ctx_in_use()) | |
65 | calls->cxl_slbia(mm); | |
66 | ||
67 | cxl_calls_put(calls); | |
68 | } | |
69 | ||
70 | int register_cxl_calls(struct cxl_calls *calls) | |
71 | { | |
72 | if (cxl_calls) | |
73 | return -EBUSY; | |
74 | ||
75 | rcu_assign_pointer(cxl_calls, calls); | |
76 | return 0; | |
77 | } | |
78 | EXPORT_SYMBOL_GPL(register_cxl_calls); | |
79 | ||
80 | void unregister_cxl_calls(struct cxl_calls *calls) | |
81 | { | |
82 | BUG_ON(cxl_calls->owner != calls->owner); | |
83 | RCU_INIT_POINTER(cxl_calls, NULL); | |
84 | synchronize_rcu(); | |
85 | } | |
86 | EXPORT_SYMBOL_GPL(unregister_cxl_calls); |