| 1 | /* |
| 2 | * urcu-checker.c |
| 3 | * |
| 4 | * Userspace RCU library checker |
| 5 | * |
| 6 | * Copyright (c) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 8 | * This library is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * This library is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with this library; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | /* |
| 24 | * NOTE: build application with -rdynamic -ldl -lurcu-common. |
| 25 | */ |
| 26 | |
| 27 | #define _GNU_SOURCE |
| 28 | #include <string.h> |
| 29 | #include <assert.h> |
| 30 | #include <stdlib.h> |
| 31 | #include <stdio.h> |
| 32 | #include <execinfo.h> |
| 33 | #include <dlfcn.h> |
| 34 | #include <sys/types.h> |
| 35 | #include <urcu/urcu-checker.h> |
| 36 | #include <urcu/tls-compat.h> |
| 37 | |
| 38 | #define URCU_DEBUG_STACK_LEN 10 |
| 39 | #define DEFAULT_PRINT_BACKTRACE_LEN 5 |
| 40 | #define BACKTRACE_LEN 16 |
| 41 | |
| 42 | #ifdef __linux__ |
| 43 | #include <syscall.h> |
| 44 | #endif |
| 45 | |
| 46 | #if defined(_syscall0) |
| 47 | _syscall0(pid_t, gettid) |
| 48 | #elif defined(__NR_gettid) |
| 49 | #include <unistd.h> |
| 50 | static inline pid_t gettid(void) |
| 51 | { |
| 52 | return syscall(__NR_gettid); |
| 53 | } |
| 54 | #else |
| 55 | #include <sys/types.h> |
| 56 | #include <unistd.h> |
| 57 | |
| 58 | /* Fall-back on getpid for tid if not available. */ |
| 59 | static inline pid_t gettid(void) |
| 60 | { |
| 61 | return getpid(); |
| 62 | } |
| 63 | #endif |
| 64 | |
| 65 | #define err_printf(fmt, args...) \ |
| 66 | fprintf(stderr, "[urcu-checker %ld/%ld] " fmt, \ |
| 67 | (long) getpid(), (long) gettid(), ## args) |
| 68 | |
| 69 | struct urcu_debug_entry { |
| 70 | void *ip; |
| 71 | int depth; |
| 72 | }; |
| 73 | |
| 74 | struct urcu_debug_stack { |
| 75 | struct urcu_debug_entry stack[URCU_DEBUG_STACK_LEN]; |
| 76 | int stackend; |
| 77 | }; |
| 78 | |
| 79 | struct backtrace { |
| 80 | void *ptrs[BACKTRACE_LEN]; |
| 81 | char **symbols; |
| 82 | }; |
| 83 | |
| 84 | static DEFINE_URCU_TLS(struct urcu_debug_stack, rcu_debug_stack); |
| 85 | |
| 86 | static volatile int print_backtrace_len = DEFAULT_PRINT_BACKTRACE_LEN; |
| 87 | |
| 88 | /* |
| 89 | * Allocates a string, or NULL. |
| 90 | */ |
| 91 | static |
| 92 | char *get_symbol(const void *caller) |
| 93 | { |
| 94 | Dl_info info; |
| 95 | char *caller_symbol; |
| 96 | |
| 97 | if (caller && dladdr(caller, &info) && info.dli_sname) { |
| 98 | caller_symbol = strdup(info.dli_sname); |
| 99 | } else { |
| 100 | caller_symbol = NULL; |
| 101 | } |
| 102 | return caller_symbol; |
| 103 | } |
| 104 | |
| 105 | static inline __attribute__((always_inline)) |
| 106 | void save_backtrace(struct backtrace *bt) |
| 107 | { |
| 108 | memset(bt, 0, sizeof(*bt)); |
| 109 | (void) backtrace(bt->ptrs, BACKTRACE_LEN); |
| 110 | bt->symbols = backtrace_symbols(bt->ptrs, BACKTRACE_LEN); |
| 111 | } |
| 112 | |
| 113 | static |
| 114 | void free_backtrace(struct backtrace *bt) |
| 115 | { |
| 116 | free(bt->symbols); |
| 117 | } |
| 118 | |
| 119 | static |
| 120 | void print_bt(struct backtrace *bt) |
| 121 | { |
| 122 | int j; |
| 123 | unsigned int empty = 1; |
| 124 | |
| 125 | for (j = 0; j < BACKTRACE_LEN; j++) { |
| 126 | if (bt->ptrs[j]) { |
| 127 | empty = 0; |
| 128 | break; |
| 129 | } |
| 130 | } |
| 131 | if (empty) |
| 132 | return; |
| 133 | |
| 134 | err_printf("[backtrace]\n"); |
| 135 | for (j = 0; j < BACKTRACE_LEN && j < print_backtrace_len; j++) { |
| 136 | if (!bt->ptrs[j]) |
| 137 | continue; |
| 138 | if (bt->symbols) |
| 139 | err_printf(" %p <%s>\n", bt->ptrs[j], bt->symbols[j]); |
| 140 | else |
| 141 | err_printf(" %p\n", bt->ptrs[j]); |
| 142 | } |
| 143 | } |
| 144 | |
| 145 | void rcu_read_lock_debug(void) |
| 146 | { |
| 147 | struct urcu_debug_stack *r = &URCU_TLS(rcu_debug_stack); |
| 148 | |
| 149 | r->stack[r->stackend++].ip = __builtin_return_address(0); |
| 150 | } |
| 151 | |
| 152 | void rcu_read_unlock_debug(void) |
| 153 | { |
| 154 | struct urcu_debug_stack *r = &URCU_TLS(rcu_debug_stack); |
| 155 | |
| 156 | assert(r->stackend != 0); |
| 157 | r->stack[--r->stackend].ip = NULL; |
| 158 | } |
| 159 | |
| 160 | void rcu_read_ongoing_check_debug(const char *func) |
| 161 | { |
| 162 | struct urcu_debug_stack *r = &URCU_TLS(rcu_debug_stack); |
| 163 | |
| 164 | if (r->stackend == 0) { |
| 165 | struct backtrace bt; |
| 166 | |
| 167 | err_printf("rcu_dereference() used outside of critical section at %p <%s>\n", |
| 168 | __builtin_return_address(0), |
| 169 | get_symbol(__builtin_return_address(0))); |
| 170 | save_backtrace(&bt); |
| 171 | print_bt(&bt); |
| 172 | free_backtrace(&bt); |
| 173 | } |
| 174 | } |