Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
locking/mutex: Use try_cmpxchg()
For simpler and better code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Yanfei Xu <yanfei.xu@windriver.com>
Link: https://lore.kernel.org/r/20210630154114.834438545@infradead.org
+6
-21
+6
-21
kernel/locking/mutex.c
+6
-21
kernel/locking/mutex.c
···
100
100
101
101
owner = atomic_long_read(&lock->owner);
102
102
for (;;) { /* must loop, can race against a flag */
103
-
unsigned long old, flags = __owner_flags(owner);
103
+
unsigned long flags = __owner_flags(owner);
104
104
unsigned long task = owner & ~MUTEX_FLAGS;
105
105
106
106
if (task) {
···
124
124
*/
125
125
flags &= ~MUTEX_FLAG_HANDOFF;
126
126
127
-
old = atomic_long_cmpxchg_acquire(&lock->owner, owner, curr | flags);
128
-
if (old == owner)
127
+
if (atomic_long_try_cmpxchg_acquire(&lock->owner, &owner, curr | flags))
129
128
return NULL;
130
-
131
-
owner = old;
132
129
}
133
130
134
131
return __owner_task(owner);
···
165
168
{
166
169
unsigned long curr = (unsigned long)current;
167
170
168
-
if (atomic_long_cmpxchg_release(&lock->owner, curr, 0UL) == curr)
169
-
return true;
170
-
171
-
return false;
171
+
return atomic_long_try_cmpxchg_release(&lock->owner, &curr, 0UL);
172
172
}
173
173
#endif
174
174
···
210
216
unsigned long owner = atomic_long_read(&lock->owner);
211
217
212
218
for (;;) {
213
-
unsigned long old, new;
219
+
unsigned long new;
214
220
215
221
#ifdef CONFIG_DEBUG_MUTEXES
216
222
DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current);
···
222
228
if (task)
223
229
new |= MUTEX_FLAG_PICKUP;
224
230
225
-
old = atomic_long_cmpxchg_release(&lock->owner, owner, new);
226
-
if (old == owner)
231
+
if (atomic_long_try_cmpxchg_release(&lock->owner, &owner, new))
227
232
break;
228
-
229
-
owner = old;
230
233
}
231
234
}
232
235
···
1220
1229
*/
1221
1230
owner = atomic_long_read(&lock->owner);
1222
1231
for (;;) {
1223
-
unsigned long old;
1224
-
1225
1232
#ifdef CONFIG_DEBUG_MUTEXES
1226
1233
DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current);
1227
1234
DEBUG_LOCKS_WARN_ON(owner & MUTEX_FLAG_PICKUP);
···
1228
1239
if (owner & MUTEX_FLAG_HANDOFF)
1229
1240
break;
1230
1241
1231
-
old = atomic_long_cmpxchg_release(&lock->owner, owner,
1232
-
__owner_flags(owner));
1233
-
if (old == owner) {
1242
+
if (atomic_long_try_cmpxchg_release(&lock->owner, &owner, __owner_flags(owner))) {
1234
1243
if (owner & MUTEX_FLAG_WAITERS)
1235
1244
break;
1236
1245
1237
1246
return;
1238
1247
}
1239
-
1240
-
owner = old;
1241
1248
}
1242
1249
1243
1250
spin_lock(&lock->wait_lock);