1*1f5207b7SJohn Levon /*
2*1f5207b7SJohn Levon * Copyright (C) 20XX Your Name.
3*1f5207b7SJohn Levon *
4*1f5207b7SJohn Levon * This program is free software; you can redistribute it and/or
5*1f5207b7SJohn Levon * modify it under the terms of the GNU General Public License
6*1f5207b7SJohn Levon * as published by the Free Software Foundation; either version 2
7*1f5207b7SJohn Levon * of the License, or (at your option) any later version.
8*1f5207b7SJohn Levon *
9*1f5207b7SJohn Levon * This program is distributed in the hope that it will be useful,
10*1f5207b7SJohn Levon * but WITHOUT ANY WARRANTY; without even the implied warranty of
11*1f5207b7SJohn Levon * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12*1f5207b7SJohn Levon * GNU General Public License for more details.
13*1f5207b7SJohn Levon *
14*1f5207b7SJohn Levon * You should have received a copy of the GNU General Public License
15*1f5207b7SJohn Levon * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16*1f5207b7SJohn Levon */
17*1f5207b7SJohn Levon
18*1f5207b7SJohn Levon /*
19*1f5207b7SJohn Levon * First of all, it's best if you lower your expectations from finding
20*1f5207b7SJohn Levon * errors to just finding suspicious code. There tends to be a lot
21*1f5207b7SJohn Levon * of false positives so having low expectations helps.
22*1f5207b7SJohn Levon *
23*1f5207b7SJohn Levon * For this test let's look for functions that return a negative value
24*1f5207b7SJohn Levon * with a semaphore held.
25*1f5207b7SJohn Levon *
26*1f5207b7SJohn Levon * This is just a template check. It's designed for teaching
27*1f5207b7SJohn Levon * only and is deliberately less useful than it could be. check_locking.c
28*1f5207b7SJohn Levon * is a better real world test.
29*1f5207b7SJohn Levon *
30*1f5207b7SJohn Levon * The biggest short coming is that it assumes a function isn't supposed
31*1f5207b7SJohn Levon * to return negative with a lock held. Also it assumes the function was
32*1f5207b7SJohn Levon * called without the lock held. It would be better if it handled the stuff
33*1f5207b7SJohn Levon * like this:
34*1f5207b7SJohn Levon * ret = -ENOMEM;
35*1f5207b7SJohn Levon * return ret;
36*1f5207b7SJohn Levon * Another idea would be to test other kinds of locks besides just semaphores.
37*1f5207b7SJohn Levon *
38*1f5207b7SJohn Levon */
39*1f5207b7SJohn Levon
40*1f5207b7SJohn Levon #include "smatch.h"
41*1f5207b7SJohn Levon #include "smatch_slist.h"
42*1f5207b7SJohn Levon
43*1f5207b7SJohn Levon static int my_id;
44*1f5207b7SJohn Levon
45*1f5207b7SJohn Levon STATE(lock);
46*1f5207b7SJohn Levon STATE(unlock);
47*1f5207b7SJohn Levon
48*1f5207b7SJohn Levon /*
49*1f5207b7SJohn Levon * unmatched_state() deals with the case where code is known to be
50*1f5207b7SJohn Levon * locked on one path but not known on the other side of a merge. Here
51*1f5207b7SJohn Levon * we assume it's the opposite.
52*1f5207b7SJohn Levon */
53*1f5207b7SJohn Levon
unmatched_state(struct sm_state * sm)54*1f5207b7SJohn Levon static struct smatch_state *unmatched_state(struct sm_state *sm)
55*1f5207b7SJohn Levon {
56*1f5207b7SJohn Levon if (sm->state == &lock)
57*1f5207b7SJohn Levon return &unlock;
58*1f5207b7SJohn Levon if (sm->state == &unlock)
59*1f5207b7SJohn Levon return &lock;
60*1f5207b7SJohn Levon return &undefined;
61*1f5207b7SJohn Levon }
62*1f5207b7SJohn Levon
match_call(struct expression * expr)63*1f5207b7SJohn Levon static void match_call(struct expression *expr)
64*1f5207b7SJohn Levon {
65*1f5207b7SJohn Levon char *fn_name;
66*1f5207b7SJohn Levon struct expression *sem_expr;
67*1f5207b7SJohn Levon char *sem_name;
68*1f5207b7SJohn Levon
69*1f5207b7SJohn Levon fn_name = expr_to_var(expr->fn);
70*1f5207b7SJohn Levon if (!fn_name || (strcmp(fn_name, "down") && strcmp(fn_name, "up")))
71*1f5207b7SJohn Levon goto free_fn;
72*1f5207b7SJohn Levon
73*1f5207b7SJohn Levon sem_expr = get_argument_from_call_expr(expr->args, 0);
74*1f5207b7SJohn Levon sem_name = expr_to_var(sem_expr);
75*1f5207b7SJohn Levon if (!strcmp(fn_name, "down")) {
76*1f5207b7SJohn Levon set_state(my_id, sem_name, NULL, &lock);
77*1f5207b7SJohn Levon } else {
78*1f5207b7SJohn Levon set_state(my_id, sem_name, NULL, &unlock);
79*1f5207b7SJohn Levon }
80*1f5207b7SJohn Levon free_string(sem_name);
81*1f5207b7SJohn Levon free_fn:
82*1f5207b7SJohn Levon free_string(fn_name);
83*1f5207b7SJohn Levon }
84*1f5207b7SJohn Levon
match_return(struct expression * ret_value)85*1f5207b7SJohn Levon static void match_return(struct expression *ret_value)
86*1f5207b7SJohn Levon {
87*1f5207b7SJohn Levon sval_t ret_val;
88*1f5207b7SJohn Levon struct stree *stree;
89*1f5207b7SJohn Levon struct sm_state *tmp;
90*1f5207b7SJohn Levon
91*1f5207b7SJohn Levon if (!get_value(ret_value, &ret_val) || sval_cmp_val(ret_val, 0) >= 0)
92*1f5207b7SJohn Levon return;
93*1f5207b7SJohn Levon
94*1f5207b7SJohn Levon stree = __get_cur_stree();
95*1f5207b7SJohn Levon FOR_EACH_MY_SM(my_id, stree, tmp) {
96*1f5207b7SJohn Levon if (tmp->state != &unlock)
97*1f5207b7SJohn Levon sm_warning("returned negative with %s semaphore held",
98*1f5207b7SJohn Levon tmp->name);
99*1f5207b7SJohn Levon } END_FOR_EACH_SM(tmp);
100*1f5207b7SJohn Levon }
101*1f5207b7SJohn Levon
check_template(int id)102*1f5207b7SJohn Levon void check_template(int id)
103*1f5207b7SJohn Levon {
104*1f5207b7SJohn Levon my_id = id;
105*1f5207b7SJohn Levon add_unmatched_state_hook(my_id, &unmatched_state);
106*1f5207b7SJohn Levon add_hook(&match_call, FUNCTION_CALL_HOOK);
107*1f5207b7SJohn Levon add_hook(&match_return, RETURN_HOOK);
108*1f5207b7SJohn Levon }
109