1 // SPDX-License-Identifier: GPL-2.0
2 #define CREATE_TRACE_POINTS
3 #include <trace/events/mmap_lock.h>
4
5 #include <linux/mm.h>
6 #include <linux/cgroup.h>
7 #include <linux/memcontrol.h>
8 #include <linux/mmap_lock.h>
9 #include <linux/mutex.h>
10 #include <linux/percpu.h>
11 #include <linux/rcupdate.h>
12 #include <linux/smp.h>
13 #include <linux/trace_events.h>
14 #include <linux/local_lock.h>
15
16 EXPORT_TRACEPOINT_SYMBOL(mmap_lock_start_locking);
17 EXPORT_TRACEPOINT_SYMBOL(mmap_lock_acquire_returned);
18 EXPORT_TRACEPOINT_SYMBOL(mmap_lock_released);
19
20 #ifdef CONFIG_MEMCG
21
22 static atomic_t reg_refcount;
23
24 /*
25 * Size of the buffer for memcg path names. Ignoring stack trace support,
26 * trace_events_hist.c uses MAX_FILTER_STR_VAL for this, so we also use it.
27 */
28 #define MEMCG_PATH_BUF_SIZE MAX_FILTER_STR_VAL
29
30 int trace_mmap_lock_reg(void)
31 {
32 atomic_inc(®_refcount);
33 return 0;
34 }
35
36 void trace_mmap_lock_unreg(void)
37 {
38 atomic_dec(®_refcount);
39 }
40
41 #define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \
42 do { \
43 char buf[MEMCG_PATH_BUF_SIZE]; \
44 get_mm_memcg_path(mm, buf, sizeof(buf)); \
45 trace_mmap_lock_##type(mm, buf, ##__VA_ARGS__); \
46 } while (0)
47
48 #else /* !CONFIG_MEMCG */
49
50 int trace_mmap_lock_reg(void)
51 {
52 return 0;
53 }
54
55 void trace_mmap_lock_unreg(void)
56 {
57 }
58
59 #define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \
60 trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
61
62 #endif /* CONFIG_MEMCG */
63
64 #ifdef CONFIG_TRACING
65 #ifdef CONFIG_MEMCG
66 /*
67 * Write the given mm_struct's memcg path to a buffer. If the path cannot be
68 * determined or the trace event is being unregistered, empty string is written.
69 */
70 static void get_mm_memcg_path(struct mm_struct *mm, char *buf, size_t buflen)
71 {
72 struct mem_cgroup *memcg;
73
74 buf[0] = '\0';
75 /* No need to get path if no trace event is registered. */
76 if (!atomic_read(®_refcount))
77 return;
78 memcg = get_mem_cgroup_from_mm(mm);
79 if (memcg == NULL)
80 return;
81 if (memcg->css.cgroup)
82 cgroup_path(memcg->css.cgroup, buf, buflen);
83 css_put(&memcg->css);
84 }
85
86 #endif /* CONFIG_MEMCG */
87
88 /*
89 * Trace calls must be in a separate file, as otherwise there's a circular
90 * dependency between linux/mmap_lock.h and trace/events/mmap_lock.h.
91 */
92
93 void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write)
94 {
95 TRACE_MMAP_LOCK_EVENT(start_locking, mm, write);
96 }
97 EXPORT_SYMBOL(__mmap_lock_do_trace_start_locking);
98
99 void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
100 bool success)
101 {
102 TRACE_MMAP_LOCK_EVENT(acquire_returned, mm, write, success);
103 }
104 EXPORT_SYMBOL(__mmap_lock_do_trace_acquire_returned);
105
106 void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write)
107 {
108 TRACE_MMAP_LOCK_EVENT(released, mm, write);
109 }
110 EXPORT_SYMBOL(__mmap_lock_do_trace_released);
111 #endif /* CONFIG_TRACING */
112
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