tools/perf/util/comm.c

   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
  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
  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
  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
  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
  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
 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
 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
 144 void comm__free(struct comm *comm)
 145 {
 146         comm_str__put(comm->comm_str);
 147         free(comm);
 148 }
 149
 150 const char *comm__str(const struct comm *comm)
 151 {
 152         return comm->comm_str->str;
 153 }