Adding debian version 4.19.249-2.debian/4.19.249-2debian

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 254 insertions, 0 deletions

diff --git a/debian/patches-rt/0129-rtmutex-Handle-the-various-new-futex-race-conditions.patch b/debian/patches-rt/0129-rtmutex-Handle-the-various-new-futex-race-conditions.patch
new file mode 100644
index 000000000..bdf75c3c6
--- /dev/null
+++ b/debian/patches-rt/0129-rtmutex-Handle-the-various-new-futex-race-conditions.patch
@@ -0,0 +1,254 @@
+From 9c83cf8ce7911f4f00f4fc71b365a30ebed5fdf4 Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Fri, 10 Jun 2011 11:04:15 +0200
+Subject: [PATCH 129/347] rtmutex: Handle the various new futex race conditions
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+RT opens a few new interesting race conditions in the rtmutex/futex
+combo due to futex hash bucket lock being a 'sleeping' spinlock and
+therefor not disabling preemption.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+---
+ kernel/futex.c                  | 77 ++++++++++++++++++++++++++-------
+ kernel/locking/rtmutex.c        | 36 ++++++++++++---
+ kernel/locking/rtmutex_common.h |  2 +
+ 3 files changed, 94 insertions(+), 21 deletions(-)
+
+diff --git a/kernel/futex.c b/kernel/futex.c
+index ac015d1dd16c..dc2d81d11b17 100644
+--- a/kernel/futex.c
++++ b/kernel/futex.c
+@@ -2253,6 +2253,16 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
+ 				requeue_pi_wake_futex(this, &key2, hb2);
+ 				drop_count++;
+ 				continue;
++			} else if (ret == -EAGAIN) {
++				/*
++				 * Waiter was woken by timeout or
++				 * signal and has set pi_blocked_on to
++				 * PI_WAKEUP_INPROGRESS before we
++				 * tried to enqueue it on the rtmutex.
++				 */
++				this->pi_state = NULL;
++				put_pi_state(pi_state);
++				continue;
+ 			} else if (ret) {
+ 				/*
+ 				 * rt_mutex_start_proxy_lock() detected a
+@@ -3331,7 +3341,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
+ {
+ 	struct hrtimer_sleeper timeout, *to = NULL;
+ 	struct rt_mutex_waiter rt_waiter;
+-	struct futex_hash_bucket *hb;
++	struct futex_hash_bucket *hb, *hb2;
+ 	union futex_key key2 = FUTEX_KEY_INIT;
+ 	struct futex_q q = futex_q_init;
+ 	int res, ret;
+@@ -3389,20 +3399,55 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
+ 	/* Queue the futex_q, drop the hb lock, wait for wakeup. */
+ 	futex_wait_queue_me(hb, &q, to);
+ 
+-	spin_lock(&hb->lock);
+-	ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
+-	spin_unlock(&hb->lock);
+-	if (ret)
+-		goto out_put_keys;
++	/*
++	 * On RT we must avoid races with requeue and trying to block
++	 * on two mutexes (hb->lock and uaddr2's rtmutex) by
++	 * serializing access to pi_blocked_on with pi_lock.
++	 */
++	raw_spin_lock_irq(&current->pi_lock);
++	if (current->pi_blocked_on) {
++		/*
++		 * We have been requeued or are in the process of
++		 * being requeued.
++		 */
++		raw_spin_unlock_irq(&current->pi_lock);
++	} else {
++		/*
++		 * Setting pi_blocked_on to PI_WAKEUP_INPROGRESS
++		 * prevents a concurrent requeue from moving us to the
++		 * uaddr2 rtmutex. After that we can safely acquire
++		 * (and possibly block on) hb->lock.
++		 */
++		current->pi_blocked_on = PI_WAKEUP_INPROGRESS;
++		raw_spin_unlock_irq(&current->pi_lock);
++
++		spin_lock(&hb->lock);
++
++		/*
++		 * Clean up pi_blocked_on. We might leak it otherwise
++		 * when we succeeded with the hb->lock in the fast
++		 * path.
++		 */
++		raw_spin_lock_irq(&current->pi_lock);
++		current->pi_blocked_on = NULL;
++		raw_spin_unlock_irq(&current->pi_lock);
++
++		ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
++		spin_unlock(&hb->lock);
++		if (ret)
++			goto out_put_keys;
++	}
+ 
+ 	/*
+-	 * In order for us to be here, we know our q.key == key2, and since
+-	 * we took the hb->lock above, we also know that futex_requeue() has
+-	 * completed and we no longer have to concern ourselves with a wakeup
+-	 * race with the atomic proxy lock acquisition by the requeue code. The
+-	 * futex_requeue dropped our key1 reference and incremented our key2
+-	 * reference count.
++	 * In order to be here, we have either been requeued, are in
++	 * the process of being requeued, or requeue successfully
++	 * acquired uaddr2 on our behalf.  If pi_blocked_on was
++	 * non-null above, we may be racing with a requeue.  Do not
++	 * rely on q->lock_ptr to be hb2->lock until after blocking on
++	 * hb->lock or hb2->lock. The futex_requeue dropped our key1
++	 * reference and incremented our key2 reference count.
+ 	 */
++	hb2 = hash_futex(&key2);
+ 
+ 	/* Check if the requeue code acquired the second futex for us. */
+ 	if (!q.rt_waiter) {
+@@ -3411,14 +3456,15 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
+ 		 * did a lock-steal - fix up the PI-state in that case.
+ 		 */
+ 		if (q.pi_state && (q.pi_state->owner != current)) {
+-			spin_lock(q.lock_ptr);
++			spin_lock(&hb2->lock);
++			BUG_ON(&hb2->lock != q.lock_ptr);
+ 			ret = fixup_pi_state_owner(uaddr2, &q, current);
+ 			/*
+ 			 * Drop the reference to the pi state which
+ 			 * the requeue_pi() code acquired for us.
+ 			 */
+ 			put_pi_state(q.pi_state);
+-			spin_unlock(q.lock_ptr);
++			spin_unlock(&hb2->lock);
+ 			/*
+ 			 * Adjust the return value. It's either -EFAULT or
+ 			 * success (1) but the caller expects 0 for success.
+@@ -3437,7 +3483,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
+ 		pi_mutex = &q.pi_state->pi_mutex;
+ 		ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter);
+ 
+-		spin_lock(q.lock_ptr);
++		spin_lock(&hb2->lock);
++		BUG_ON(&hb2->lock != q.lock_ptr);
+ 		if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter))
+ 			ret = 0;
+ 
+diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
+index 4bec24dfafc6..9d472eb48ba7 100644
+--- a/kernel/locking/rtmutex.c
++++ b/kernel/locking/rtmutex.c
+@@ -135,6 +135,11 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
+ 		WRITE_ONCE(*p, owner & ~RT_MUTEX_HAS_WAITERS);
+ }
+ 
++static int rt_mutex_real_waiter(struct rt_mutex_waiter *waiter)
++{
++	return waiter && waiter != PI_WAKEUP_INPROGRESS;
++}
++
+ /*
+  * We can speed up the acquire/release, if there's no debugging state to be
+  * set up.
+@@ -379,7 +384,8 @@ int max_lock_depth = 1024;
+ 
+ static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
+ {
+-	return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
++	return rt_mutex_real_waiter(p->pi_blocked_on) ?
++		p->pi_blocked_on->lock : NULL;
+ }
+ 
+ /*
+@@ -515,7 +521,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
+ 	 * reached or the state of the chain has changed while we
+ 	 * dropped the locks.
+ 	 */
+-	if (!waiter)
++	if (!rt_mutex_real_waiter(waiter))
+ 		goto out_unlock_pi;
+ 
+ 	/*
+@@ -951,6 +957,22 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
+ 		return -EDEADLK;
+ 
+ 	raw_spin_lock(&task->pi_lock);
++	/*
++	 * In the case of futex requeue PI, this will be a proxy
++	 * lock. The task will wake unaware that it is enqueueed on
++	 * this lock. Avoid blocking on two locks and corrupting
++	 * pi_blocked_on via the PI_WAKEUP_INPROGRESS
++	 * flag. futex_wait_requeue_pi() sets this when it wakes up
++	 * before requeue (due to a signal or timeout). Do not enqueue
++	 * the task if PI_WAKEUP_INPROGRESS is set.
++	 */
++	if (task != current && task->pi_blocked_on == PI_WAKEUP_INPROGRESS) {
++		raw_spin_unlock(&task->pi_lock);
++		return -EAGAIN;
++	}
++
++       BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on));
++
+ 	waiter->task = task;
+ 	waiter->lock = lock;
+ 	waiter->prio = task->prio;
+@@ -974,7 +996,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
+ 		rt_mutex_enqueue_pi(owner, waiter);
+ 
+ 		rt_mutex_adjust_prio(owner);
+-		if (owner->pi_blocked_on)
++		if (rt_mutex_real_waiter(owner->pi_blocked_on))
+ 			chain_walk = 1;
+ 	} else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) {
+ 		chain_walk = 1;
+@@ -1070,7 +1092,7 @@ static void remove_waiter(struct rt_mutex *lock,
+ {
+ 	bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock));
+ 	struct task_struct *owner = rt_mutex_owner(lock);
+-	struct rt_mutex *next_lock;
++	struct rt_mutex *next_lock = NULL;
+ 
+ 	lockdep_assert_held(&lock->wait_lock);
+ 
+@@ -1096,7 +1118,8 @@ static void remove_waiter(struct rt_mutex *lock,
+ 	rt_mutex_adjust_prio(owner);
+ 
+ 	/* Store the lock on which owner is blocked or NULL */
+-	next_lock = task_blocked_on_lock(owner);
++	if (rt_mutex_real_waiter(owner->pi_blocked_on))
++		next_lock = task_blocked_on_lock(owner);
+ 
+ 	raw_spin_unlock(&owner->pi_lock);
+ 
+@@ -1132,7 +1155,8 @@ void 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 (!rt_mutex_real_waiter(waiter) ||
++	    rt_mutex_waiter_equal(waiter, task_to_waiter(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 ca6fb489007b..8f39bc139735 100644
+--- a/kernel/locking/rtmutex_common.h
++++ b/kernel/locking/rtmutex_common.h
+@@ -130,6 +130,8 @@ enum rtmutex_chainwalk {
+ /*
+  * PI-futex support (proxy locking functions, etc.):
+  */
++#define PI_WAKEUP_INPROGRESS	((struct rt_mutex_waiter *) 1)
++
+ extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
+ extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+ 				       struct task_struct *proxy_owner);
+-- 
+2.36.1
+