tools/perf/util/pstack.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Simple pointer stack
   4  *
   5  * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
   6  */
   7
   8 #include "pstack.h"
   9 #include "debug.h"
  10 #include <linux/kernel.h>
  11 #include <linux/zalloc.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14
  15 struct pstack {
  16         unsigned short  top;
  17         unsigned short  max_nr_entries;
  18         void            *entries[0];
  19 };
  20
  21 struct pstack *pstack__new(unsigned short max_nr_entries)
  22 {
  23         struct pstack *pstack = zalloc((sizeof(*pstack) +
  24                                        max_nr_entries * sizeof(void *)));
  25         if (pstack != NULL)
  26                 pstack->max_nr_entries = max_nr_entries;
  27         return pstack;
  28 }
  29
  30 void pstack__delete(struct pstack *pstack)
  31 {
  32         free(pstack);
  33 }
  34
  35 bool pstack__empty(const struct pstack *pstack)
  36 {
  37         return pstack->top == 0;
  38 }
  39
  40 void pstack__remove(struct pstack *pstack, void *key)
  41 {
  42         unsigned short i = pstack->top, last_index = pstack->top - 1;
  43
  44         while (i-- != 0) {
  45                 if (pstack->entries[i] == key) {
  46                         if (i < last_index)
  47                                 memmove(pstack->entries + i,
  48                                         pstack->entries + i + 1,
  49                                         (last_index - i) * sizeof(void *));
  50                         --pstack->top;
  51                         return;
  52                 }
  53         }
  54         pr_err("%s: %p not on the pstack!\n", __func__, key);
  55 }
  56
  57 void pstack__push(struct pstack *pstack, void *key)
  58 {
  59         if (pstack->top == pstack->max_nr_entries) {
  60                 pr_err("%s: top=%d, overflow!\n", __func__, pstack->top);
  61                 return;
  62         }
  63         pstack->entries[pstack->top++] = key;
  64 }
  65
  66 void *pstack__pop(struct pstack *pstack)
  67 {
  68         void *ret;
  69
  70         if (pstack->top == 0) {
  71                 pr_err("%s: underflow!\n", __func__);
  72                 return NULL;
  73         }
  74
  75         ret = pstack->entries[--pstack->top];
  76         pstack->entries[pstack->top] = NULL;
  77         return ret;
  78 }
  79
  80 void *pstack__peek(struct pstack *pstack)
  81 {
  82         if (pstack->top == 0)
  83                 return NULL;
  84         return pstack->entries[pstack->top - 1];
  85 }