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-rw-r--r--kernel/futex.c67
1 files changed, 37 insertions, 30 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 82cd270f25a0..a316dce74c3d 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1263,6 +1263,36 @@ static int handle_exit_race(u32 __user *uaddr, u32 uval,
return -ESRCH;
}
+static void __attach_to_pi_owner(struct task_struct *p, union futex_key *key,
+ struct futex_pi_state **ps)
+{
+ /*
+ * No existing pi state. First waiter. [2]
+ *
+ * This creates pi_state, we have hb->lock held, this means nothing can
+ * observe this state, wait_lock is irrelevant.
+ */
+ struct futex_pi_state *pi_state = alloc_pi_state();
+
+ /*
+ * Initialize the pi_mutex in locked state and make @p
+ * the owner of it:
+ */
+ rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p);
+
+ /* Store the key for possible exit cleanups: */
+ pi_state->key = *key;
+
+ WARN_ON(!list_empty(&pi_state->list));
+ list_add(&pi_state->list, &p->pi_state_list);
+ /*
+ * Assignment without holding pi_state->pi_mutex.wait_lock is safe
+ * because there is no concurrency as the object is not published yet.
+ */
+ pi_state->owner = p;
+
+ *ps = pi_state;
+}
/*
* Lookup the task for the TID provided from user space and attach to
* it after doing proper sanity checks.
@@ -1272,7 +1302,6 @@ static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key,
struct task_struct **exiting)
{
pid_t pid = uval & FUTEX_TID_MASK;
- struct futex_pi_state *pi_state;
struct task_struct *p;
/*
@@ -1324,36 +1353,11 @@ static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key,
return ret;
}
- /*
- * No existing pi state. First waiter. [2]
- *
- * This creates pi_state, we have hb->lock held, this means nothing can
- * observe this state, wait_lock is irrelevant.
- */
- pi_state = alloc_pi_state();
-
- /*
- * Initialize the pi_mutex in locked state and make @p
- * the owner of it:
- */
- rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p);
-
- /* Store the key for possible exit cleanups: */
- pi_state->key = *key;
-
- WARN_ON(!list_empty(&pi_state->list));
- list_add(&pi_state->list, &p->pi_state_list);
- /*
- * Assignment without holding pi_state->pi_mutex.wait_lock is safe
- * because there is no concurrency as the object is not published yet.
- */
- pi_state->owner = p;
+ __attach_to_pi_owner(p, key, ps);
raw_spin_unlock_irq(&p->pi_lock);
put_task_struct(p);
- *ps = pi_state;
-
return 0;
}
@@ -1464,11 +1468,14 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
* @task is guaranteed to be alive and it cannot be exiting
* because it is either sleeping or waiting in
* futex_requeue_pi_wakeup_sync().
+ *
+ * No need to do the full attach_to_pi_owner() exercise
+ * because @task is known and valid.
*/
if (set_waiters) {
- ret = attach_to_pi_owner(uaddr, newval, key, ps,
- exiting);
- WARN_ON(ret);
+ raw_spin_lock_irq(&task->pi_lock);
+ __attach_to_pi_owner(task, key, ps);
+ raw_spin_unlock_irq(&task->pi_lock);
}
return 1;
}