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
12 struct 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 */
19 static struct rb_root comm_str_root;
20 static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,};
21
comm_str__get(struct comm_str * cs)22 static 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
comm_str__put(struct comm_str * cs)30 static 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
comm_str__alloc(const char * str)41 static 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
60 static
__comm_str__findnew(const char * str,struct rb_root * root)61 struct 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
comm_str__findnew(const char * str,struct rb_root * root)97 static 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
comm__new(const char * str,u64 timestamp,bool exec)108 struct 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
comm__override(struct comm * comm,const char * str,u64 timestamp,bool exec)127 int 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
comm__free(struct comm * comm)144 void comm__free(struct comm *comm)
145 {
146 comm_str__put(comm->comm_str);
147 free(comm);
148 }
149
comm__str(const struct comm * comm)150 const char *comm__str(const struct comm *comm)
151 {
152 return comm->comm_str->str;
153 }
154