1// SPDX-License-Identifier: GPL-2.0
2#include "comm.h"
3#include <errno.h>
4#include <stdlib.h>
5#include <stdio.h>
6#include <string.h>
7#include <linux/refcount.h>
8#include <linux/rbtree.h>
9#include <linux/zalloc.h>
10#include "rwsem.h"
11
12struct comm_str {
13	char *str;
14	struct rb_node rb_node;
15	refcount_t refcnt;
16};
17
18/* Should perhaps be moved to struct machine */
19static struct rb_root comm_str_root;
20static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,};
21
22static struct comm_str *comm_str__get(struct comm_str *cs)
23{
24	if (cs && refcount_inc_not_zero(&cs->refcnt))
25		return cs;
26
27	return NULL;
28}
29
30static void comm_str__put(struct comm_str *cs)
31{
32	if (cs && refcount_dec_and_test(&cs->refcnt)) {
33		down_write(&comm_str_lock);
34		rb_erase(&cs->rb_node, &comm_str_root);
35		up_write(&comm_str_lock);
36		zfree(&cs->str);
37		free(cs);
38	}
39}
40
41static struct comm_str *comm_str__alloc(const char *str)
42{
43	struct comm_str *cs;
44
45	cs = zalloc(sizeof(*cs));
46	if (!cs)
47		return NULL;
48
49	cs->str = strdup(str);
50	if (!cs->str) {
51		free(cs);
52		return NULL;
53	}
54
55	refcount_set(&cs->refcnt, 1);
56
57	return cs;
58}
59
60static
61struct comm_str *__comm_str__findnew(const char *str, struct rb_root *root)
62{
63	struct rb_node **p = &root->rb_node;
64	struct rb_node *parent = NULL;
65	struct comm_str *iter, *new;
66	int cmp;
67
68	while (*p != NULL) {
69		parent = *p;
70		iter = rb_entry(parent, struct comm_str, rb_node);
71
72		/*
73		 * If we race with comm_str__put, iter->refcnt is 0
74		 * and it will be removed within comm_str__put call
75		 * shortly, ignore it in this search.
76		 */
77		cmp = strcmp(str, iter->str);
78		if (!cmp && comm_str__get(iter))
79			return iter;
80
81		if (cmp < 0)
82			p = &(*p)->rb_left;
83		else
84			p = &(*p)->rb_right;
85	}
86
87	new = comm_str__alloc(str);
88	if (!new)
89		return NULL;
90
91	rb_link_node(&new->rb_node, parent, p);
92	rb_insert_color(&new->rb_node, root);
93
94	return new;
95}
96
97static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root)
98{
99	struct comm_str *cs;
100
101	down_write(&comm_str_lock);
102	cs = __comm_str__findnew(str, root);
103	up_write(&comm_str_lock);
104
105	return cs;
106}
107
108struct comm *comm__new(const char *str, u64 timestamp, bool exec)
109{
110	struct comm *comm = zalloc(sizeof(*comm));
111
112	if (!comm)
113		return NULL;
114
115	comm->start = timestamp;
116	comm->exec = exec;
117
118	comm->comm_str = comm_str__findnew(str, &comm_str_root);
119	if (!comm->comm_str) {
120		free(comm);
121		return NULL;
122	}
123
124	return comm;
125}
126
127int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec)
128{
129	struct comm_str *new, *old = comm->comm_str;
130
131	new = comm_str__findnew(str, &comm_str_root);
132	if (!new)
133		return -ENOMEM;
134
135	comm_str__put(old);
136	comm->comm_str = new;
137	comm->start = timestamp;
138	if (exec)
139		comm->exec = true;
140
141	return 0;
142}
143
144void comm__free(struct comm *comm)
145{
146	comm_str__put(comm->comm_str);
147	free(comm);
148}
149
150const char *comm__str(const struct comm *comm)
151{
152	return comm->comm_str->str;
153}
154