Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 2823d41..2874bf5 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* RT-Mutexes: simple blocking mutual exclusion locks with PI support
*
@@ -8,7 +9,7 @@
* Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
* Copyright (C) 2006 Esben Nielsen
*
- * See Documentation/locking/rt-mutex-design.txt for details.
+ * See Documentation/locking/rt-mutex-design.rst for details.
*/
#include <linux/spinlock.h>
#include <linux/export.h>
@@ -627,8 +628,7 @@
}
/* [10] Grab the next task, i.e. owner of @lock */
- task = rt_mutex_owner(lock);
- get_task_struct(task);
+ task = get_task_struct(rt_mutex_owner(lock));
raw_spin_lock(&task->pi_lock);
/*
@@ -708,8 +708,7 @@
}
/* [10] Grab the next task, i.e. the owner of @lock */
- task = rt_mutex_owner(lock);
- get_task_struct(task);
+ task = get_task_struct(rt_mutex_owner(lock));
raw_spin_lock(&task->pi_lock);
/* [11] requeue the pi waiters if necessary */
@@ -1485,9 +1484,9 @@
__rt_mutex_lock(lock, subclass);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
-#endif
-#ifndef CONFIG_DEBUG_LOCK_ALLOC
+#else /* !CONFIG_DEBUG_LOCK_ALLOC */
+
/**
* rt_mutex_lock - lock a rt_mutex
*
@@ -1726,12 +1725,33 @@
rt_mutex_set_owner(lock, NULL);
}
+/**
+ * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task
+ * @lock: the rt_mutex to take
+ * @waiter: the pre-initialized rt_mutex_waiter
+ * @task: the task to prepare
+ *
+ * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
+ * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
+ *
+ * NOTE: does _NOT_ remove the @waiter on failure; must either call
+ * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this.
+ *
+ * Returns:
+ * 0 - task blocked on lock
+ * 1 - acquired the lock for task, caller should wake it up
+ * <0 - error
+ *
+ * Special API call for PI-futex support.
+ */
int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task)
{
int ret;
+ lockdep_assert_held(&lock->wait_lock);
+
if (try_to_take_rt_mutex(lock, task, NULL))
return 1;
@@ -1749,9 +1769,6 @@
ret = 0;
}
- if (unlikely(ret))
- remove_waiter(lock, waiter);
-
debug_rt_mutex_print_deadlock(waiter);
return ret;
@@ -1763,12 +1780,18 @@
* @waiter: the pre-initialized rt_mutex_waiter
* @task: the task to prepare
*
+ * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
+ * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
+ *
+ * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter
+ * on failure.
+ *
* Returns:
* 0 - task blocked on lock
* 1 - acquired the lock for task, caller should wake it up
* <0 - error
*
- * Special API call for FUTEX_REQUEUE_PI support.
+ * Special API call for PI-futex support.
*/
int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
@@ -1778,6 +1801,8 @@
raw_spin_lock_irq(&lock->wait_lock);
ret = __rt_mutex_start_proxy_lock(lock, waiter, task);
+ if (unlikely(ret))
+ remove_waiter(lock, waiter);
raw_spin_unlock_irq(&lock->wait_lock);
return ret;
@@ -1845,7 +1870,8 @@
* @lock: the rt_mutex we were woken on
* @waiter: the pre-initialized rt_mutex_waiter
*
- * Attempt to clean up after a failed rt_mutex_wait_proxy_lock().
+ * Attempt to clean up after a failed __rt_mutex_start_proxy_lock() or
+ * rt_mutex_wait_proxy_lock().
*
* Unless we acquired the lock; we're still enqueued on the wait-list and can
* in fact still be granted ownership until we're removed. Therefore we can