[ANNOUNCE] v6.4.6-rt8

From: Sebastian Andrzej Siewior
Date: Thu Jul 27 2023 - 06:35:29 EST

Dear RT folks!

I'm pleased to announce the v6.4.6-rt8 patch set.

Changes since v6.4.6-rt7:

- Hu Chunyu reported that a task can be released in the wrong context.
This can happen for instance if the task is using the DL scheduling
policy. Patch by Wander Lairson.

- Henry Wu reported a problem within the rtmutex code that can occur
during PI-boosting. Patch by Peter Zijlstra.

- Paul Gortmaker reported a warning during reset in the i915 driver.
Patch by Tvrtko Ursulin.

Known issues
None

The delta patch against v6.4.6-rt7 is appended below and can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.4/incr/patch-6.4.6-rt7-rt8.patch.xz

You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v6.4.6-rt8

The RT patch against v6.4.6 can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.4/older/patch-6.4.6-rt8.patch.xz

The split quilt queue is available at:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.4/older/patches-6.4.6-rt8.tar.xz

Sebastian

diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index 797ea8340467e..21e50c7d8ce91 100644
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -166,13 +166,13 @@ static int i915_do_reset(struct intel_gt *gt,
/* Assert reset for at least 20 usec, and wait for acknowledgement. */
pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
udelay(50);
- err = wait_for_atomic(i915_in_reset(pdev), 50);
+ err = _wait_for_atomic(i915_in_reset(pdev), 50, 0);

/* Clear the reset request. */
pci_write_config_byte(pdev, I915_GDRST, 0);
udelay(50);
if (!err)
- err = wait_for_atomic(!i915_in_reset(pdev), 50);
+ err = _wait_for_atomic(!i915_in_reset(pdev), 50, 0);

return err;
}
@@ -192,7 +192,7 @@ static int g33_do_reset(struct intel_gt *gt,
struct pci_dev *pdev = to_pci_dev(gt->i915->drm.dev);

pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
- return wait_for_atomic(g4x_reset_complete(pdev), 50);
+ return _wait_for_atomic(g4x_reset_complete(pdev), 50, 0);
}

static int g4x_do_reset(struct intel_gt *gt,
@@ -209,7 +209,7 @@ static int g4x_do_reset(struct intel_gt *gt,

pci_write_config_byte(pdev, I915_GDRST,
GRDOM_MEDIA | GRDOM_RESET_ENABLE);
- ret = wait_for_atomic(g4x_reset_complete(pdev), 50);
+ ret = _wait_for_atomic(g4x_reset_complete(pdev), 50, 0);
if (ret) {
GT_TRACE(gt, "Wait for media reset failed\n");
goto out;
@@ -217,7 +217,7 @@ static int g4x_do_reset(struct intel_gt *gt,

pci_write_config_byte(pdev, I915_GDRST,
GRDOM_RENDER | GRDOM_RESET_ENABLE);
- ret = wait_for_atomic(g4x_reset_complete(pdev), 50);
+ ret = _wait_for_atomic(g4x_reset_complete(pdev), 50, 0);
if (ret) {
GT_TRACE(gt, "Wait for render reset failed\n");
goto out;
@@ -787,9 +787,7 @@ int __intel_gt_reset(struct intel_gt *gt, intel_engine_mask_t engine_mask)
reset_mask = wa_14015076503_start(gt, engine_mask, !retry);

GT_TRACE(gt, "engine_mask=%x\n", reset_mask);
- preempt_disable();
ret = reset(gt, reset_mask, retry);
- preempt_enable();

wa_14015076503_end(gt, reset_mask);
}
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index e0f5ac90a228b..b539090277714 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -118,11 +118,47 @@ static inline struct task_struct *get_task_struct(struct task_struct *t)
}

extern void __put_task_struct(struct task_struct *t);
+extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);

static inline void put_task_struct(struct task_struct *t)
{
- if (refcount_dec_and_test(&t->usage))
+ if (!refcount_dec_and_test(&t->usage))
+ return;
+
+ /*
+ * In !RT, it is always safe to call __put_task_struct().
+ * Under RT, we can only call it in preemptible context.
+ */
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
+ static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
+
+ lock_map_acquire_try(&put_task_map);
__put_task_struct(t);
+ lock_map_release(&put_task_map);
+ return;
+ }
+
+ /*
+ * under PREEMPT_RT, we can't call put_task_struct
+ * in atomic context because it will indirectly
+ * acquire sleeping locks.
+ *
+ * call_rcu() will schedule delayed_put_task_struct_rcu()
+ * to be called in process context.
+ *
+ * __put_task_struct() is called when
+ * refcount_dec_and_test(&t->usage) succeeds.
+ *
+ * This means that it can't "conflict" with
+ * put_task_struct_rcu_user() which abuses ->rcu the same
+ * way; rcu_users has a reference so task->usage can't be
+ * zero after rcu_users 1 -> 0 transition.
+ *
+ * delayed_free_task() also uses ->rcu, but it is only called
+ * when it fails to fork a process. Therefore, there is no
+ * way it can conflict with put_task_struct().
+ */
+ call_rcu(&t->rcu, __put_task_struct_rcu_cb);
}

static inline void put_task_struct_many(struct task_struct *t, int nr)
diff --git a/kernel/fork.c b/kernel/fork.c
index 8103ffd217e97..38cfcfbd8b489 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -989,6 +989,14 @@ void __put_task_struct(struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(__put_task_struct);

+void __put_task_struct_rcu_cb(struct rcu_head *rhp)
+{
+ struct task_struct *task = container_of(rhp, struct task_struct, rcu);
+
+ __put_task_struct(task);
+}
+EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb);
+
void __init __weak arch_task_cache_init(void) { }

/*
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 479a9487edcc2..08a4555076f73 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -356,21 +356,43 @@ static __always_inline int __waiter_prio(struct task_struct *task)
return prio;
}

+/*
+ * Update the waiter->tree copy of the sort keys.
+ */
static __always_inline void
waiter_update_prio(struct rt_mutex_waiter *waiter, struct task_struct *task)
{
- waiter->prio = __waiter_prio(task);
- waiter->deadline = task->dl.deadline;
+ lockdep_assert_held(&waiter->lock->wait_lock);
+ lockdep_assert(RB_EMPTY_NODE(&waiter->tree.entry));
+
+ waiter->tree.prio = __waiter_prio(task);
+ waiter->tree.deadline = task->dl.deadline;
}

/*
- * Only use with rt_mutex_waiter_{less,equal}()
+ * Update the waiter->pi_tree copy of the sort keys (from the tree copy).
*/
-#define task_to_waiter(p) \
- &(struct rt_mutex_waiter){ .prio = __waiter_prio(p), .deadline = (p)->dl.deadline }
+static __always_inline void
+waiter_clone_prio(struct rt_mutex_waiter *waiter, struct task_struct *task)
+{
+ lockdep_assert_held(&waiter->lock->wait_lock);
+ lockdep_assert_held(&task->pi_lock);
+ lockdep_assert(RB_EMPTY_NODE(&waiter->pi_tree.entry));

-static __always_inline int rt_mutex_waiter_less(struct rt_mutex_waiter *left,
- struct rt_mutex_waiter *right)
+ waiter->pi_tree.prio = waiter->tree.prio;
+ waiter->pi_tree.deadline = waiter->tree.deadline;
+}
+
+/*
+ * Only use with rt_waiter_node_{less,equal}()
+ */
+#define task_to_waiter_node(p) \
+ &(struct rt_waiter_node){ .prio = __waiter_prio(p), .deadline = (p)->dl.deadline }
+#define task_to_waiter(p) \
+ &(struct rt_mutex_waiter){ .tree = *task_to_waiter_node(p) }
+
+static __always_inline int rt_waiter_node_less(struct rt_waiter_node *left,
+ struct rt_waiter_node *right)
{
if (left->prio < right->prio)
return 1;
@@ -387,8 +409,8 @@ static __always_inline int rt_mutex_waiter_less(struct rt_mutex_waiter *left,
return 0;
}

-static __always_inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
- struct rt_mutex_waiter *right)
+static __always_inline int rt_waiter_node_equal(struct rt_waiter_node *left,
+ struct rt_waiter_node *right)
{
if (left->prio != right->prio)
return 0;
@@ -408,7 +430,7 @@ static __always_inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
static inline bool rt_mutex_steal(struct rt_mutex_waiter *waiter,
struct rt_mutex_waiter *top_waiter)
{
- if (rt_mutex_waiter_less(waiter, top_waiter))
+ if (rt_waiter_node_less(&waiter->tree, &top_waiter->tree))
return true;

#ifdef RT_MUTEX_BUILD_SPINLOCKS
@@ -416,30 +438,30 @@ static inline bool rt_mutex_steal(struct rt_mutex_waiter *waiter,
* Note that RT tasks are excluded from same priority (lateral)
* steals to prevent the introduction of an unbounded latency.
*/
- if (rt_prio(waiter->prio) || dl_prio(waiter->prio))
+ if (rt_prio(waiter->tree.prio) || dl_prio(waiter->tree.prio))
return false;

- return rt_mutex_waiter_equal(waiter, top_waiter);
+ return rt_waiter_node_equal(&waiter->tree, &top_waiter->tree);
#else
return false;
#endif
}

#define __node_2_waiter(node) \
- rb_entry((node), struct rt_mutex_waiter, tree_entry)
+ rb_entry((node), struct rt_mutex_waiter, tree.entry)

static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_node *b)
{
struct rt_mutex_waiter *aw = __node_2_waiter(a);
struct rt_mutex_waiter *bw = __node_2_waiter(b);

- if (rt_mutex_waiter_less(aw, bw))
+ if (rt_waiter_node_less(&aw->tree, &bw->tree))
return 1;

if (!build_ww_mutex())
return 0;

- if (rt_mutex_waiter_less(bw, aw))
+ if (rt_waiter_node_less(&bw->tree, &aw->tree))
return 0;

/* NOTE: relies on waiter->ww_ctx being set before insertion */
@@ -457,48 +479,58 @@ static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_nod
static __always_inline void
rt_mutex_enqueue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
{
- rb_add_cached(&waiter->tree_entry, &lock->waiters, __waiter_less);
+ lockdep_assert_held(&lock->wait_lock);
+
+ rb_add_cached(&waiter->tree.entry, &lock->waiters, __waiter_less);
}

static __always_inline void
rt_mutex_dequeue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
{
- if (RB_EMPTY_NODE(&waiter->tree_entry))
+ lockdep_assert_held(&lock->wait_lock);
+
+ if (RB_EMPTY_NODE(&waiter->tree.entry))
return;

- rb_erase_cached(&waiter->tree_entry, &lock->waiters);
- RB_CLEAR_NODE(&waiter->tree_entry);
+ rb_erase_cached(&waiter->tree.entry, &lock->waiters);
+ RB_CLEAR_NODE(&waiter->tree.entry);
}

-#define __node_2_pi_waiter(node) \
- rb_entry((node), struct rt_mutex_waiter, pi_tree_entry)
+#define __node_2_rt_node(node) \
+ rb_entry((node), struct rt_waiter_node, entry)

-static __always_inline bool
-__pi_waiter_less(struct rb_node *a, const struct rb_node *b)
+static __always_inline bool __pi_waiter_less(struct rb_node *a, const struct rb_node *b)
{
- return rt_mutex_waiter_less(__node_2_pi_waiter(a), __node_2_pi_waiter(b));
+ return rt_waiter_node_less(__node_2_rt_node(a), __node_2_rt_node(b));
}

static __always_inline void
rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
{
- rb_add_cached(&waiter->pi_tree_entry, &task->pi_waiters, __pi_waiter_less);
+ lockdep_assert_held(&task->pi_lock);
+
+ rb_add_cached(&waiter->pi_tree.entry, &task->pi_waiters, __pi_waiter_less);
}

static __always_inline void
rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
{
- if (RB_EMPTY_NODE(&waiter->pi_tree_entry))
+ lockdep_assert_held(&task->pi_lock);
+
+ if (RB_EMPTY_NODE(&waiter->pi_tree.entry))
return;

- rb_erase_cached(&waiter->pi_tree_entry, &task->pi_waiters);
- RB_CLEAR_NODE(&waiter->pi_tree_entry);
+ rb_erase_cached(&waiter->pi_tree.entry, &task->pi_waiters);
+ RB_CLEAR_NODE(&waiter->pi_tree.entry);
}

-static __always_inline void rt_mutex_adjust_prio(struct task_struct *p)
+static __always_inline void rt_mutex_adjust_prio(struct rt_mutex_base *lock,
+ struct task_struct *p)
{
struct task_struct *pi_task = NULL;

+ lockdep_assert_held(&lock->wait_lock);
+ lockdep_assert(rt_mutex_owner(lock) == p);
lockdep_assert_held(&p->pi_lock);

if (task_has_pi_waiters(p))
@@ -594,9 +626,14 @@ static __always_inline struct rt_mutex_base *task_blocked_on_lock(struct task_st
* Chain walk basics and protection scope
*
* [R] refcount on task
- * [P] task->pi_lock held
+ * [Pn] task->pi_lock held
* [L] rtmutex->wait_lock held
*
+ * Normal locking order:
+ *
+ * rtmutex->wait_lock
+ * task->pi_lock
+ *
* Step Description Protected by
* function arguments:
* @task [R]
@@ -611,27 +648,32 @@ static __always_inline struct rt_mutex_base *task_blocked_on_lock(struct task_st
* again:
* loop_sanity_check();
* retry:
- * [1] lock(task->pi_lock); [R] acquire [P]
- * [2] waiter = task->pi_blocked_on; [P]
- * [3] check_exit_conditions_1(); [P]
- * [4] lock = waiter->lock; [P]
- * [5] if (!try_lock(lock->wait_lock)) { [P] try to acquire [L]
- * unlock(task->pi_lock); release [P]
+ * [1] lock(task->pi_lock); [R] acquire [P1]
+ * [2] waiter = task->pi_blocked_on; [P1]
+ * [3] check_exit_conditions_1(); [P1]
+ * [4] lock = waiter->lock; [P1]
+ * [5] if (!try_lock(lock->wait_lock)) { [P1] try to acquire [L]
+ * unlock(task->pi_lock); release [P1]
* goto retry;
* }
- * [6] check_exit_conditions_2(); [P] + [L]
- * [7] requeue_lock_waiter(lock, waiter); [P] + [L]
- * [8] unlock(task->pi_lock); release [P]
+ * [6] check_exit_conditions_2(); [P1] + [L]
+ * [7] requeue_lock_waiter(lock, waiter); [P1] + [L]
+ * [8] unlock(task->pi_lock); release [P1]
* put_task_struct(task); release [R]
* [9] check_exit_conditions_3(); [L]
* [10] task = owner(lock); [L]
* get_task_struct(task); [L] acquire [R]
- * lock(task->pi_lock); [L] acquire [P]
- * [11] requeue_pi_waiter(tsk, waiters(lock));[P] + [L]
- * [12] check_exit_conditions_4(); [P] + [L]
- * [13] unlock(task->pi_lock); release [P]
+ * lock(task->pi_lock); [L] acquire [P2]
+ * [11] requeue_pi_waiter(tsk, waiters(lock));[P2] + [L]
+ * [12] check_exit_conditions_4(); [P2] + [L]
+ * [13] unlock(task->pi_lock); release [P2]
* unlock(lock->wait_lock); release [L]
* goto again;
+ *
+ * Where P1 is the blocking task and P2 is the lock owner; going up one step
+ * the owner becomes the next blocked task etc..
+ *
+*
*/
static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
enum rtmutex_chainwalk chwalk,
@@ -779,7 +821,7 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
* enabled we continue, but stop the requeueing in the chain
* walk.
*/
- if (rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
+ if (rt_waiter_node_equal(&waiter->tree, task_to_waiter_node(task))) {
if (!detect_deadlock)
goto out_unlock_pi;
else
@@ -787,13 +829,18 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
}

/*
- * [4] Get the next lock
+ * [4] Get the next lock; per holding task->pi_lock we can't unblock
+ * and guarantee @lock's existence.
*/
lock = waiter->lock;
/*
* [5] We need to trylock here as we are holding task->pi_lock,
* which is the reverse lock order versus the other rtmutex
* operations.
+ *
+ * Per the above, holding task->pi_lock guarantees lock exists, so
+ * inverting this lock order is infeasible from a life-time
+ * perspective.
*/
if (!raw_spin_trylock(&lock->wait_lock)) {
raw_spin_unlock_irq(&task->pi_lock);
@@ -897,17 +944,18 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
* or
*
* DL CBS enforcement advancing the effective deadline.
- *
- * Even though pi_waiters also uses these fields, and that tree is only
- * updated in [11], we can do this here, since we hold [L], which
- * serializes all pi_waiters access and rb_erase() does not care about
- * the values of the node being removed.
*/
waiter_update_prio(waiter, task);

rt_mutex_enqueue(lock, waiter);

- /* [8] Release the task */
+ /*
+ * [8] Release the (blocking) task in preparation for
+ * taking the owner task in [10].
+ *
+ * Since we hold lock->waiter_lock, task cannot unblock, even if we
+ * release task->pi_lock.
+ */
raw_spin_unlock(&task->pi_lock);
put_task_struct(task);

@@ -931,7 +979,12 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
return 0;
}

- /* [10] Grab the next task, i.e. the owner of @lock */
+ /*
+ * [10] Grab the next task, i.e. the owner of @lock
+ *
+ * Per holding lock->wait_lock and checking for !owner above, there
+ * must be an owner and it cannot go away.
+ */
task = get_task_struct(rt_mutex_owner(lock));
raw_spin_lock(&task->pi_lock);

@@ -944,8 +997,9 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
* and adjust the priority of the owner.
*/
rt_mutex_dequeue_pi(task, prerequeue_top_waiter);
+ waiter_clone_prio(waiter, task);
rt_mutex_enqueue_pi(task, waiter);
- rt_mutex_adjust_prio(task);
+ rt_mutex_adjust_prio(lock, task);

} else if (prerequeue_top_waiter == waiter) {
/*
@@ -960,8 +1014,9 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
*/
rt_mutex_dequeue_pi(task, waiter);
waiter = rt_mutex_top_waiter(lock);
+ waiter_clone_prio(waiter, task);
rt_mutex_enqueue_pi(task, waiter);
- rt_mutex_adjust_prio(task);
+ rt_mutex_adjust_prio(lock, task);
} else {
/*
* Nothing changed. No need to do any priority
@@ -1177,6 +1232,7 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
waiter->task = task;
waiter->lock = lock;
waiter_update_prio(waiter, task);
+ waiter_clone_prio(waiter, task);

/* Get the top priority waiter on the lock */
if (rt_mutex_has_waiters(lock))
@@ -1210,7 +1266,7 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
rt_mutex_dequeue_pi(owner, top_waiter);
rt_mutex_enqueue_pi(owner, waiter);

- rt_mutex_adjust_prio(owner);
+ rt_mutex_adjust_prio(lock, owner);
if (owner->pi_blocked_on)
chain_walk = 1;
} else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) {
@@ -1257,6 +1313,8 @@ static void __sched mark_wakeup_next_waiter(struct rt_wake_q_head *wqh,
{
struct rt_mutex_waiter *waiter;

+ lockdep_assert_held(&lock->wait_lock);
+
raw_spin_lock(&current->pi_lock);

waiter = rt_mutex_top_waiter(lock);
@@ -1269,7 +1327,7 @@ static void __sched mark_wakeup_next_waiter(struct rt_wake_q_head *wqh,
* task unblocks.
*/
rt_mutex_dequeue_pi(current, waiter);
- rt_mutex_adjust_prio(current);
+ rt_mutex_adjust_prio(lock, current);

/*
* As we are waking up the top waiter, and the waiter stays
@@ -1505,7 +1563,7 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
if (rt_mutex_has_waiters(lock))
rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock));

- rt_mutex_adjust_prio(owner);
+ rt_mutex_adjust_prio(lock, owner);

/* Store the lock on which owner is blocked or NULL */
next_lock = task_blocked_on_lock(owner);
diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c
index cb9fdff76a8a3..a6974d0445930 100644
--- a/kernel/locking/rtmutex_api.c
+++ b/kernel/locking/rtmutex_api.c
@@ -459,7 +459,7 @@ void __sched rt_mutex_adjust_pi(struct task_struct *task)
raw_spin_lock_irqsave(&task->pi_lock, flags);

waiter = task->pi_blocked_on;
- if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
+ if (!waiter || rt_waiter_node_equal(&waiter->tree, task_to_waiter_node(task))) {
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
return;
}
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index c47e8361bfb5c..1162e07cdaea1 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -17,27 +17,44 @@
#include <linux/rtmutex.h>
#include <linux/sched/wake_q.h>

+
+/*
+ * This is a helper for the struct rt_mutex_waiter below. A waiter goes in two
+ * separate trees and they need their own copy of the sort keys because of
+ * different locking requirements.
+ *
+ * @entry: rbtree node to enqueue into the waiters tree
+ * @prio: Priority of the waiter
+ * @deadline: Deadline of the waiter if applicable
+ *
+ * See rt_waiter_node_less() and waiter_*_prio().
+ */
+struct rt_waiter_node {
+ struct rb_node entry;
+ int prio;
+ u64 deadline;
+};
+
/*
* This is the control structure for tasks blocked on a rt_mutex,
* which is allocated on the kernel stack on of the blocked task.
*
- * @tree_entry: pi node to enqueue into the mutex waiters tree
- * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
+ * @tree: node to enqueue into the mutex waiters tree
+ * @pi_tree: node to enqueue into the mutex owner waiters tree
* @task: task reference to the blocked task
* @lock: Pointer to the rt_mutex on which the waiter blocks
* @wake_state: Wakeup state to use (TASK_NORMAL or TASK_RTLOCK_WAIT)
- * @prio: Priority of the waiter
- * @deadline: Deadline of the waiter if applicable
* @ww_ctx: WW context pointer
+ *
+ * @tree is ordered by @lock->wait_lock
+ * @pi_tree is ordered by rt_mutex_owner(@lock)->pi_lock
*/
struct rt_mutex_waiter {
- struct rb_node tree_entry;
- struct rb_node pi_tree_entry;
+ struct rt_waiter_node tree;
+ struct rt_waiter_node pi_tree;
struct task_struct *task;
struct rt_mutex_base *lock;
unsigned int wake_state;
- int prio;
- u64 deadline;
struct ww_acquire_ctx *ww_ctx;
};

@@ -105,7 +122,7 @@ static inline bool rt_mutex_waiter_is_top_waiter(struct rt_mutex_base *lock,
{
struct rb_node *leftmost = rb_first_cached(&lock->waiters);

- return rb_entry(leftmost, struct rt_mutex_waiter, tree_entry) == waiter;
+ return rb_entry(leftmost, struct rt_mutex_waiter, tree.entry) == waiter;
}

static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex_base *lock)
@@ -113,8 +130,10 @@ static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex_base *
struct rb_node *leftmost = rb_first_cached(&lock->waiters);
struct rt_mutex_waiter *w = NULL;

+ lockdep_assert_held(&lock->wait_lock);
+
if (leftmost) {
- w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
+ w = rb_entry(leftmost, struct rt_mutex_waiter, tree.entry);
BUG_ON(w->lock != lock);
}
return w;
@@ -127,8 +146,10 @@ static inline int task_has_pi_waiters(struct task_struct *p)

static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p)
{
+ lockdep_assert_held(&p->pi_lock);
+
return rb_entry(p->pi_waiters.rb_leftmost, struct rt_mutex_waiter,
- pi_tree_entry);
+ pi_tree.entry);
}

#define RT_MUTEX_HAS_WAITERS 1UL
@@ -190,8 +211,8 @@ static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
static inline void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
{
debug_rt_mutex_init_waiter(waiter);
- RB_CLEAR_NODE(&waiter->pi_tree_entry);
- RB_CLEAR_NODE(&waiter->tree_entry);
+ RB_CLEAR_NODE(&waiter->pi_tree.entry);
+ RB_CLEAR_NODE(&waiter->tree.entry);
waiter->wake_state = TASK_NORMAL;
waiter->task = NULL;
}
diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
index 56f139201f246..3ad2cc4823e59 100644
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -96,25 +96,25 @@ __ww_waiter_first(struct rt_mutex *lock)
struct rb_node *n = rb_first(&lock->rtmutex.waiters.rb_root);
if (!n)
return NULL;
- return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+ return rb_entry(n, struct rt_mutex_waiter, tree.entry);
}

static inline struct rt_mutex_waiter *
__ww_waiter_next(struct rt_mutex *lock, struct rt_mutex_waiter *w)
{
- struct rb_node *n = rb_next(&w->tree_entry);
+ struct rb_node *n = rb_next(&w->tree.entry);
if (!n)
return NULL;
- return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+ return rb_entry(n, struct rt_mutex_waiter, tree.entry);
}

static inline struct rt_mutex_waiter *
__ww_waiter_prev(struct rt_mutex *lock, struct rt_mutex_waiter *w)
{
- struct rb_node *n = rb_prev(&w->tree_entry);
+ struct rb_node *n = rb_prev(&w->tree.entry);
if (!n)
return NULL;
- return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+ return rb_entry(n, struct rt_mutex_waiter, tree.entry);
}

static inline struct rt_mutex_waiter *
@@ -123,7 +123,7 @@ __ww_waiter_last(struct rt_mutex *lock)
struct rb_node *n = rb_last(&lock->rtmutex.waiters.rb_root);
if (!n)
return NULL;
- return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+ return rb_entry(n, struct rt_mutex_waiter, tree.entry);
}

static inline void
diff --git a/localversion-rt b/localversion-rt
index 045478966e9f1..700c857efd9ba 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt7
+-rt8