LXR linux/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
  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