smatch_kernel_kref_put.c

   1 /*
   2  * Copyright 2023 Linaro Ltd.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 #include "smatch.h"
  19 #include "smatch_extra.h"
  20 #include "smatch_slist.h"
  21
  22 static int my_id;
  23
  24 static bool has_inc_state(const char *name, struct symbol *sym)
  25 {
  26         static int refcount_id;
  27         struct sm_state *sm, *tmp;
  28
  29         if (!refcount_id)
  30                 refcount_id = id_from_name("check_refcount_info");
  31
  32         sm = get_sm_state(refcount_id, name, sym);
  33         if (!sm)
  34                 return false;
  35
  36         FOR_EACH_PTR(sm->possible, tmp) {
  37                 if (strcmp(tmp->state->name, "inc") == 0)
  38                         return true;
  39                 /*
  40                  * &ignore counts as an inc, because that's what happens when
  41                  * you double increment.  Not ideal.
  42                  */
  43                 if (strcmp(tmp->state->name, "ignore") == 0)
  44                         return true;
  45         } END_FOR_EACH_PTR(tmp);
  46
  47         return false;
  48 }
  49
  50 static void match_kref_put(const char *fn, struct expression *call_expr,
  51                            struct expression *expr, void *_unused)
  52 {
  53         struct expression *data, *release, *fake_call;
  54         struct expression_list *args = NULL;
  55         struct symbol *sym;
  56         char *ref;
  57
  58
  59         if (call_expr->type != EXPR_CALL)
  60                 return;
  61
  62         data = get_argument_from_call_expr(call_expr->args, 0);
  63
  64         ref = get_name_sym_from_param_key(call_expr, 0, "$->refcount.refs.counter", &sym);
  65         if (has_inc_state(ref, sym))
  66                 return;
  67
  68         release = get_argument_from_call_expr(call_expr->args, 1);
  69
  70         add_ptr_list(&args, data);
  71         fake_call = call_expression(release, args);
  72         add_fake_call_after_return(fake_call);
  73 }
  74
  75 void register_kernel_kref_put(int id)
  76 {
  77         if (option_project != PROJ_KERNEL)
  78                 return;
  79
  80         my_id = id;
  81         return_implies_state_sval("kref_put", int_one, int_one, &match_kref_put, NULL);
  82 }