summaryrefslogtreecommitdiff
path: root/tools/perf/util/comm.c
blob: 49b79cf0c5cc513bf66d160413cdcca40317b05d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
// SPDX-License-Identifier: GPL-2.0
#include "comm.h"
#include <errno.h>
#include <string.h>
#include <internal/rc_check.h>
#include <linux/refcount.h>
#include <linux/zalloc.h>
#include "rwsem.h"

DECLARE_RC_STRUCT(comm_str) {
	refcount_t refcnt;
	char str[];
};

static struct comm_strs {
	struct rw_semaphore lock;
	struct comm_str **strs;
	int num_strs;
	int capacity;
} _comm_strs;

static void comm_strs__remove_if_last(struct comm_str *cs);

static void comm_strs__init(void)
{
	init_rwsem(&_comm_strs.lock);
	_comm_strs.capacity = 16;
	_comm_strs.num_strs = 0;
	_comm_strs.strs = calloc(16, sizeof(*_comm_strs.strs));
}

static struct comm_strs *comm_strs__get(void)
{
	static pthread_once_t comm_strs_type_once = PTHREAD_ONCE_INIT;

	pthread_once(&comm_strs_type_once, comm_strs__init);

	return &_comm_strs;
}

static refcount_t *comm_str__refcnt(struct comm_str *cs)
{
	return &RC_CHK_ACCESS(cs)->refcnt;
}

static const char *comm_str__str(const struct comm_str *cs)
{
	return &RC_CHK_ACCESS(cs)->str[0];
}

static struct comm_str *comm_str__get(struct comm_str *cs)
{
	struct comm_str *result;

	if (RC_CHK_GET(result, cs))
		refcount_inc_not_zero(comm_str__refcnt(cs));

	return result;
}

static void comm_str__put(struct comm_str *cs)
{
	if (!cs)
		return;

	if (refcount_dec_and_test(comm_str__refcnt(cs))) {
		RC_CHK_FREE(cs);
	} else {
		if (refcount_read(comm_str__refcnt(cs)) == 1)
			comm_strs__remove_if_last(cs);

		RC_CHK_PUT(cs);
	}
}

static struct comm_str *comm_str__new(const char *str)
{
	struct comm_str *result = NULL;
	RC_STRUCT(comm_str) *cs;

	cs = malloc(sizeof(*cs) + strlen(str) + 1);
	if (ADD_RC_CHK(result, cs)) {
		refcount_set(comm_str__refcnt(result), 1);
		strcpy(&cs->str[0], str);
	}
	return result;
}

static int comm_str__search(const void *_key, const void *_member)
{
	const char *key = _key;
	const struct comm_str *member = *(const struct comm_str * const *)_member;

	return strcmp(key, comm_str__str(member));
}

static void comm_strs__remove_if_last(struct comm_str *cs)
{
	struct comm_strs *comm_strs = comm_strs__get();

	down_write(&comm_strs->lock);
	/*
	 * Are there only references from the array, if so remove the array
	 * reference under the write lock so that we don't race with findnew.
	 */
	if (refcount_read(comm_str__refcnt(cs)) == 1) {
		struct comm_str **entry;

		entry = bsearch(comm_str__str(cs), comm_strs->strs, comm_strs->num_strs,
				sizeof(struct comm_str *), comm_str__search);
		comm_str__put(*entry);
		for (int i = entry - comm_strs->strs; i < comm_strs->num_strs - 1; i++)
			comm_strs->strs[i] = comm_strs->strs[i + 1];
		comm_strs->num_strs--;
	}
	up_write(&comm_strs->lock);
}

static struct comm_str *__comm_strs__find(struct comm_strs *comm_strs, const char *str)
{
	struct comm_str **result;

	result = bsearch(str, comm_strs->strs, comm_strs->num_strs, sizeof(struct comm_str *),
			 comm_str__search);

	if (!result)
		return NULL;

	return comm_str__get(*result);
}

static struct comm_str *comm_strs__findnew(const char *str)
{
	struct comm_strs *comm_strs = comm_strs__get();
	struct comm_str *result;

	if (!comm_strs)
		return NULL;

	down_read(&comm_strs->lock);
	result = __comm_strs__find(comm_strs, str);
	up_read(&comm_strs->lock);
	if (result)
		return result;

	down_write(&comm_strs->lock);
	result = __comm_strs__find(comm_strs, str);
	if (!result) {
		if (comm_strs->num_strs == comm_strs->capacity) {
			struct comm_str **tmp;

			tmp = reallocarray(comm_strs->strs,
					   comm_strs->capacity + 16,
					   sizeof(*comm_strs->strs));
			if (!tmp) {
				up_write(&comm_strs->lock);
				return NULL;
			}
			comm_strs->strs = tmp;
			comm_strs->capacity += 16;
		}
		result = comm_str__new(str);
		if (result) {
			int low = 0, high = comm_strs->num_strs - 1;
			int insert = comm_strs->num_strs; /* Default to inserting at the end. */

			while (low <= high) {
				int mid = low + (high - low) / 2;
				int cmp = strcmp(comm_str__str(comm_strs->strs[mid]), str);

				if (cmp < 0) {
					low = mid + 1;
				} else {
					high = mid - 1;
					insert = mid;
				}
			}
			memmove(&comm_strs->strs[insert + 1], &comm_strs->strs[insert],
				(comm_strs->num_strs - insert) * sizeof(struct comm_str *));
			comm_strs->num_strs++;
			comm_strs->strs[insert] = result;
		}
	}
	up_write(&comm_strs->lock);
	return comm_str__get(result);
}

struct comm *comm__new(const char *str, u64 timestamp, bool exec)
{
	struct comm *comm = zalloc(sizeof(*comm));

	if (!comm)
		return NULL;

	comm->start = timestamp;
	comm->exec = exec;

	comm->comm_str = comm_strs__findnew(str);
	if (!comm->comm_str) {
		free(comm);
		return NULL;
	}

	return comm;
}

int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec)
{
	struct comm_str *new, *old = comm->comm_str;

	new = comm_strs__findnew(str);
	if (!new)
		return -ENOMEM;

	comm_str__put(old);
	comm->comm_str = new;
	comm->start = timestamp;
	if (exec)
		comm->exec = true;

	return 0;
}

void comm__free(struct comm *comm)
{
	comm_str__put(comm->comm_str);
	free(comm);
}

const char *comm__str(const struct comm *comm)
{
	return comm_str__str(comm->comm_str);
}