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 /* 107 * We are now relying on the NMI watchdog to detect lockup instead of doing 108 * the detection here with an unfair lock which can cause problem of its own. 109 */ 110 void do_raw_spin_lock(raw_spinlock_t *lock) 111 { 112 debug_spin_lock_before(lock); 113 arch_spin_lock(&lock->raw_lock); 114 mmiowb_spin_lock(); 115 debug_spin_lock_after(lock); 116 } 117 118 int do_raw_spin_trylock(raw_spinlock_t *lock) 119 { 120 int ret = arch_spin_trylock(&lock->raw_lock); 121 122 if (ret) { 123 mmiowb_spin_lock(); 124 debug_spin_lock_after(lock); 125 } 126 #ifndef CONFIG_SMP 127 /* 128 * Must not happen on UP: 129 */ 130 SPIN_BUG_ON(!ret, lock, "trylock failure on UP"); 131 #endif 132 return ret; 133 } 134 135 void do_raw_spin_unlock(raw_spinlock_t *lock) 136 { 137 mmiowb_spin_unlock(); 138 debug_spin_unlock(lock); 139 arch_spin_unlock(&lock->raw_lock); 140 } 141 142 static void rwlock_bug(rwlock_t *lock, const char *msg) 143 { 144 if (!debug_locks_off()) 145 return; 146 147 printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n", 148 msg, raw_smp_processor_id(), current->comm, 149 task_pid_nr(current), lock); 150 dump_stack(); 151 } 152 153 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg) 154 155 void do_raw_read_lock(rwlock_t *lock) 156 { 157 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 158 arch_read_lock(&lock->raw_lock); 159 } 160 161 int do_raw_read_trylock(rwlock_t *lock) 162 { 163 int ret = arch_read_trylock(&lock->raw_lock); 164 165 #ifndef CONFIG_SMP 166 /* 167 * Must not happen on UP: 168 */ 169 RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); 170 #endif 171 return ret; 172 } 173 174 void do_raw_read_unlock(rwlock_t *lock) 175 { 176 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 177 arch_read_unlock(&lock->raw_lock); 178 } 179 180 static inline void debug_write_lock_before(rwlock_t *lock) 181 { 182 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 183 RWLOCK_BUG_ON(lock->owner == current, lock, "recursion"); 184 RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), 185 lock, "cpu recursion"); 186 } 187 188 static inline void debug_write_lock_after(rwlock_t *lock) 189 { 190 lock->owner_cpu = raw_smp_processor_id(); 191 lock->owner = current; 192 } 193 194 static inline void debug_write_unlock(rwlock_t *lock) 195 { 196 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); 197 RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner"); 198 RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), 199 lock, "wrong CPU"); 200 lock->owner = SPINLOCK_OWNER_INIT; 201 lock->owner_cpu = -1; 202 } 203 204 void do_raw_write_lock(rwlock_t *lock) 205 { 206 debug_write_lock_before(lock); 207 arch_write_lock(&lock->raw_lock); 208 debug_write_lock_after(lock); 209 } 210 211 int do_raw_write_trylock(rwlock_t *lock) 212 { 213 int ret = arch_write_trylock(&lock->raw_lock); 214 215 if (ret) 216 debug_write_lock_after(lock); 217 #ifndef CONFIG_SMP 218 /* 219 * Must not happen on UP: 220 */ 221 RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); 222 #endif 223 return ret; 224 } 225 226 void do_raw_write_unlock(rwlock_t *lock) 227 { 228 debug_write_unlock(lock); 229 arch_write_unlock(&lock->raw_lock); 230 } 231