LXR linux/tools/perf/util/comm.c

   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
  11struct 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 */
  18static struct rb_root comm_str_root;
  19static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,};
  20
  21static 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
  29static 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
  40static 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
  59static
  60struct 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
  96static 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
 107struct 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
 126int 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
 143void comm__free(struct comm *comm)
 144{
 145        comm_str__put(comm->comm_str);
 146        free(comm);
 147}
 148
 149const char *comm__str(const struct comm *comm)
 150{
 151        return comm->comm_str->str;
 152}
 153