1 /* 2 * Copyright 2005, Red Hat, Inc., Ingo Molnar 3 * Released under the General Public License (GPL). 4 * 5 * This file contains the spinlock/rwlock implementations for 6 * DEBUG_SPINLOCK. 7 */ 8 9 #include <linux/spinlock.h> 10 #include <linux/nmi.h> 11 #include <linux/interrupt.h> 12 #include <linux/debug_locks.h> 13 #include <linux/delay.h> 14 #include <linux/export.h> 15 16 void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name, 17 struct lock_class_key *key) 18 { 19 #ifdef CONFIG_DEBUG_LOCK_ALLOC 20 /* 21 * Make sure we are not reinitializing a held lock: 22 */ 23 debug_check_no_locks_freed((void *)lock, sizeof(*lock)); 24 lockdep_init_map(&lock->dep_map, name, key, 0); 25 #endif 26 lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; 27 lock->magic = SPINLOCK_MAGIC; 28 lock->owner = SPINLOCK_OWNER_INIT; 29 lock->owner_cpu = -1; 30 } 31 32 EXPORT_SYMBOL(__raw_spin_lock_init); 33 34 void __rwlock_init(rwlock_t *lock, const char *name, 35 struct lock_class_key *key) 36 { 37 #ifdef CONFIG_DEBUG_LOCK_ALLOC 38 /* 39 * Make sure we are not reinitializing a held lock: 40 */ 41 debug_check_no_locks_freed((void *)lock, sizeof(*lock)); 42 lockdep_init_map(&lock->dep_map, name, key, 0); 43 #endif 44 lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED; 45 lock->magic = RWLOCK_MAGIC; 46 lock->owner = SPINLOCK_OWNER_INIT; 47 lock->owner_cpu = -1; 48 } 49 50 EXPORT_SYMBOL(__rwlock_init); 51 52 static void spin_dump(raw_spinlock_t *lock, const char *msg) 53 { 54 struct task_struct *owner = NULL; 55 56 if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT) 57 owner = lock->owner; 58 printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n", 59 msg, raw_smp_processor_id(), 60 current->comm, task_pid_nr(current)); 61 printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, " 62 ".owner_cpu: %d\n", 63 lock, lock->magic, 64 owner ? owner->comm : "<none>", 65 owner ? task_pid_nr(owner) : -1, 66 lock->owner_cpu); 67 dump_stack(); 68 } 69 70 static void spin_bug(raw_spinlock_t *lock, const char *msg) 71 { 72 if (!debug_locks_off()) 73 return; 74 75 spin_dump(lock, msg); 76 } 77 78 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg) 79 80 static inline void 81 debug_spin_lock_before(raw_spinlock_t *lock) 82 { 83 SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); 84 SPIN_BUG_ON(lock->owner == current, lock, "recursion"); 85 SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), 86 lock, "cpu recursion"); 87 } 88 89 static inline void debug_spin_lock_after(raw_spinlock_t *lock) 90 { 91 lock->owner_cpu = raw_smp_processor_id(); 92 lock->owner = current; 93 } 94 95 static inline void debug_spin_unlock(raw_spinlock_t *lock) 96 { 97 SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); 98 SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked"); 99 SPIN_BUG_ON(lock->owner != current, lock, "wrong owner"); 100 SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), 101 lock, "wrong CPU"); 102 lock->owner = SPINLOCK_OWNER_INIT; 103 lock->owner_cpu = -1; 104 } 105 106 static void __spin_lock_debug(raw_spinlock_t *lock) 107 { 108 u64 i; 109 u64 loops = loops_per_jiffy * HZ; 110 111 for (i = 0; i < loops; i++) { 112 if (arch_spin_trylock(&lock->raw_lock)) 113 return; 114 __delay(1); 115 } 116 /* lockup suspected: */ 117 spin_dump(lock, "lockup suspected"); 118 #ifdef CONFIG_SMP 119 trigger_all_cpu_backtrace(); 120 #endif 121 122 /* 123 * The trylock above was causing a livelock. Give the lower level arch 124 * specific lock code a chance to acquire the lock. We have already 125 * printed a warning/backtrace at this point. The non-debug arch 126 * specific code might actually succeed in acquiring the lock. If it is 127 * not successful, the end-result is the same - there is no forward 128 * progress. 129 */ 130 arch_spin_lock(&lock->raw_lock); 131 } 132 133 void do_raw_spin_lock(raw_spinlock_t *lock) 134 { 135 debug_spin_lock_before(lock); 136 if (unlikely(!arch_spin_trylock(&lock->raw_lock))) 137 __spin_lock_debug(lock); 138 debug_spin_lock_after(lock); 139 } 140 141 int do_raw_spin_trylock(raw_spinlock_t *lock) 142 { 143 int ret = arch_spin_trylock(&lock->raw_lock); 144 145 if (ret) 146 debug_spin_lock_after(lock); 147 #ifndef CONFIG_SMP 148 /* 149 * Must not happen on UP: 150 */ 151 SPIN_BUG_ON(!ret, lock, "trylock failure on UP"); 152 #endif 153 return ret; 154 } 155 156 void do_raw_spin_unlock(raw_spinlock_t *lock) 157 { 158 debug_spin_unlock(lock); 159 arch_spin_unlock(&lock->raw_lock); 160 } 161 162 static void rwlock_bug(rwlock_t *lock, const char *msg) 163 { 164 if (!debug_locks_off()) 165 return; 166 167 printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n", 168 msg, raw_smp_processor_id(), current->comm, 169 task_pid_nr(current), lock); 170 dump_stack(); 171 } 172 173 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg) 174 175 #if 0 /* __write_lock_debug() can lock up - maybe this can too? */ 176 static void __read_lock_debug(rwlock_t *lock) 177 { 178 u64 i; 179 u64 loops = loops_per_jiffy * HZ; 180 int print_once = 1; 181 182 for (;;) { 183 for (i = 0; i < loops; i++) { 184 if (arch_read_trylock(&lock->raw_lock)) 185 return; 186 __delay(1); 187 } 188 /* lockup suspected: */ 189 if (print_once) { 190 print_once = 0; 191 printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, " 192 "%s/%d, %p\n", 193 raw_smp_processor_id(), current->comm, 194 current->pid, lock); 195 dump_stack(); 196 } 197 } 198 } 199 #endif 200 201 void do_raw_read_lock(rwlock_t *lock) 202 { 203 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 204 arch_read_lock(&lock->raw_lock); 205 } 206 207 int do_raw_read_trylock(rwlock_t *lock) 208 { 209 int ret = arch_read_trylock(&lock->raw_lock); 210 211 #ifndef CONFIG_SMP 212 /* 213 * Must not happen on UP: 214 */ 215 RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); 216 #endif 217 return ret; 218 } 219 220 void do_raw_read_unlock(rwlock_t *lock) 221 { 222 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 223 arch_read_unlock(&lock->raw_lock); 224 } 225 226 static inline void debug_write_lock_before(rwlock_t *lock) 227 { 228 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 229 RWLOCK_BUG_ON(lock->owner == current, lock, "recursion"); 230 RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), 231 lock, "cpu recursion"); 232 } 233 234 static inline void debug_write_lock_after(rwlock_t *lock) 235 { 236 lock->owner_cpu = raw_smp_processor_id(); 237 lock->owner = current; 238 } 239 240 static inline void debug_write_unlock(rwlock_t *lock) 241 { 242 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 243 RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner"); 244 RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), 245 lock, "wrong CPU"); 246 lock->owner = SPINLOCK_OWNER_INIT; 247 lock->owner_cpu = -1; 248 } 249 250 #if 0 /* This can cause lockups */ 251 static void __write_lock_debug(rwlock_t *lock) 252 { 253 u64 i; 254 u64 loops = loops_per_jiffy * HZ; 255 int print_once = 1; 256 257 for (;;) { 258 for (i = 0; i < loops; i++) { 259 if (arch_write_trylock(&lock->raw_lock)) 260 return; 261 __delay(1); 262 } 263 /* lockup suspected: */ 264 if (print_once) { 265 print_once = 0; 266 printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, " 267 "%s/%d, %p\n", 268 raw_smp_processor_id(), current->comm, 269 current->pid, lock); 270 dump_stack(); 271 } 272 } 273 } 274 #endif 275 276 void do_raw_write_lock(rwlock_t *lock) 277 { 278 debug_write_lock_before(lock); 279 arch_write_lock(&lock->raw_lock); 280 debug_write_lock_after(lock); 281 } 282 283 int do_raw_write_trylock(rwlock_t *lock) 284 { 285 int ret = arch_write_trylock(&lock->raw_lock); 286 287 if (ret) 288 debug_write_lock_after(lock); 289 #ifndef CONFIG_SMP 290 /* 291 * Must not happen on UP: 292 */ 293 RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); 294 #endif 295 return ret; 296 } 297 298 void do_raw_write_unlock(rwlock_t *lock) 299 { 300 debug_write_unlock(lock); 301 arch_write_unlock(&lock->raw_lock); 302 } 303