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