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-rw-r--r--lib/rwsem.c22
1 files changed, 2 insertions, 20 deletions
diff --git a/lib/rwsem.c b/lib/rwsem.c
index fb658af1c12c..66f307e90761 100644
--- a/lib/rwsem.c
+++ b/lib/rwsem.c
@@ -182,7 +182,6 @@ try_again_write:
182 */ 182 */
183struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem) 183struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
184{ 184{
185 enum rwsem_waiter_type type = RWSEM_WAITING_FOR_READ;
186 signed long adjustment = -RWSEM_ACTIVE_READ_BIAS; 185 signed long adjustment = -RWSEM_ACTIVE_READ_BIAS;
187 struct rwsem_waiter waiter; 186 struct rwsem_waiter waiter;
188 struct task_struct *tsk = current; 187 struct task_struct *tsk = current;
@@ -190,7 +189,7 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
190 189
191 /* set up my own style of waitqueue */ 190 /* set up my own style of waitqueue */
192 waiter.task = tsk; 191 waiter.task = tsk;
193 waiter.type = type; 192 waiter.type = RWSEM_WAITING_FOR_READ;
194 get_task_struct(tsk); 193 get_task_struct(tsk);
195 194
196 raw_spin_lock_irq(&sem->wait_lock); 195 raw_spin_lock_irq(&sem->wait_lock);
@@ -201,17 +200,9 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
201 /* we're now waiting on the lock, but no longer actively locking */ 200 /* we're now waiting on the lock, but no longer actively locking */
202 count = rwsem_atomic_update(adjustment, sem); 201 count = rwsem_atomic_update(adjustment, sem);
203 202
204 /* If there are no active locks, wake the front queued process(es) up. 203 /* If there are no active locks, wake the front queued process(es). */
205 *
206 * Alternatively, if we're called from a failed down_write(), there
207 * were already threads queued before us and there are no active
208 * writers, the lock must be read owned; so we try to wake any read
209 * locks that were queued ahead of us. */
210 if (count == RWSEM_WAITING_BIAS) 204 if (count == RWSEM_WAITING_BIAS)
211 sem = __rwsem_do_wake(sem, RWSEM_WAKE_NO_ACTIVE); 205 sem = __rwsem_do_wake(sem, RWSEM_WAKE_NO_ACTIVE);
212 else if (count > RWSEM_WAITING_BIAS &&
213 adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
214 sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
215 206
216 raw_spin_unlock_irq(&sem->wait_lock); 207 raw_spin_unlock_irq(&sem->wait_lock);
217 208
@@ -220,15 +211,6 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
220 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 211 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
221 if (!waiter.task) 212 if (!waiter.task)
222 break; 213 break;
223
224 raw_spin_lock_irq(&sem->wait_lock);
225 /* Try to get the writer sem, may steal from the head writer: */
226 if (type == RWSEM_WAITING_FOR_WRITE)
227 if (try_get_writer_sem(sem, &waiter)) {
228 raw_spin_unlock_irq(&sem->wait_lock);
229 return sem;
230 }
231 raw_spin_unlock_irq(&sem->wait_lock);
232 schedule(); 214 schedule();
233 } 215 }
234 216