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Subject[ANNOUNCE] v4.9.18-rt14
Dear RT folks!

I'm pleased to announce the v4.9.18-rt14 patch set.

Changes since v4.9.18-rt13:

- v4.9.11-rt9 had a fix for statically initialized PER_CPU locks. An
issue with nested locks came up which was noticed by the kernel test
robot and fixed by Peter Zijlstra.

- A larger rework of the futex / rtmutex code. In v4.8-rt1 we added a
workaround so we don't de-boost too early in the unlock path. A
small window remained in which the locking thread could de-boost the
unlocking thread. This rework by Peter Zijlstra fixes the issue.

Known issues
- CPU hotplug got a little better but can deadlock.
- The radeon driver. Probably since a change in the driver (or
DRM core) the radeon driver can hang. This problem starts probably
with the v3.18 release.
- gdb. While gdb is following a task it is possible that after a
fork() operation the task is waiting for gdb and gdb waiting
for the task.

The delta patch against v4.9.18-rt13 is appended below and can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/incr/patch-4.9.18-rt13-rt14.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 v4.9.18-rt14

The RT patch against v4.9.18 can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patch-4.9.18-rt14.patch.xz

The split quilt queue is available at:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patches-4.9.18-rt14.tar.xz

Sebastian
diff --git a/include/linux/smp.h b/include/linux/smp.h
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -120,6 +120,13 @@ extern unsigned int setup_max_cpus;
extern void __init setup_nr_cpu_ids(void);
extern void __init smp_init(void);

+extern int __boot_cpu_id;
+
+static inline int get_boot_cpu_id(void)
+{
+ return __boot_cpu_id;
+}
+
#else /* !SMP */

static inline void smp_send_stop(void) { }
@@ -158,6 +165,11 @@ static inline void smp_init(void) { up_late_init(); }
static inline void smp_init(void) { }
#endif

+static inline int get_boot_cpu_id(void)
+{
+ return 0;
+}
+
#endif /* !SMP */

/*
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -355,12 +355,6 @@ static __always_inline void spin_unlock(spinlock_t *lock)
raw_spin_unlock(&lock->rlock);
}

-static __always_inline int spin_unlock_no_deboost(spinlock_t *lock)
-{
- raw_spin_unlock(&lock->rlock);
- return 0;
-}
-
static __always_inline void spin_unlock_bh(spinlock_t *lock)
{
raw_spin_unlock_bh(&lock->rlock);
diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
--- a/include/linux/spinlock_rt.h
+++ b/include/linux/spinlock_rt.h
@@ -26,7 +26,6 @@ extern void __lockfunc rt_spin_lock(spinlock_t *lock);
extern unsigned long __lockfunc rt_spin_lock_trace_flags(spinlock_t *lock);
extern void __lockfunc rt_spin_lock_nested(spinlock_t *lock, int subclass);
extern void __lockfunc rt_spin_unlock(spinlock_t *lock);
-extern int __lockfunc rt_spin_unlock_no_deboost(spinlock_t *lock);
extern void __lockfunc rt_spin_unlock_wait(spinlock_t *lock);
extern int __lockfunc rt_spin_trylock_irqsave(spinlock_t *lock, unsigned long *flags);
extern int __lockfunc rt_spin_trylock_bh(spinlock_t *lock);
@@ -112,7 +111,6 @@ static inline unsigned long spin_lock_trace_flags(spinlock_t *lock)
#define spin_lock_nest_lock(lock, nest_lock) spin_lock_nested(lock, 0)

#define spin_unlock(lock) rt_spin_unlock(lock)
-#define spin_unlock_no_deboost(lock) rt_spin_unlock_no_deboost(lock)

#define spin_unlock_bh(lock) \
do { \
diff --git a/kernel/cpu.c b/kernel/cpu.c
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1562,6 +1562,8 @@ core_initcall(cpu_hotplug_pm_sync_init);

#endif /* CONFIG_PM_SLEEP_SMP */

+int __boot_cpu_id;
+
#endif /* CONFIG_SMP */

/* Boot processor state steps */
@@ -2245,6 +2247,10 @@ void __init boot_cpu_init(void)
set_cpu_active(cpu, true);
set_cpu_present(cpu, true);
set_cpu_possible(cpu, true);
+
+#ifdef CONFIG_SMP
+ __boot_cpu_id = cpu;
+#endif
}

/*
diff --git a/kernel/futex.c b/kernel/futex.c
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -800,7 +800,7 @@ static int refill_pi_state_cache(void)
return 0;
}

-static struct futex_pi_state * alloc_pi_state(void)
+static struct futex_pi_state *alloc_pi_state(void)
{
struct futex_pi_state *pi_state = current->pi_state_cache;

@@ -810,6 +810,11 @@ static struct futex_pi_state * alloc_pi_state(void)
return pi_state;
}

+static void get_pi_state(struct futex_pi_state *pi_state)
+{
+ WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount));
+}
+
/*
* Drops a reference to the pi_state object and frees or caches it
* when the last reference is gone.
@@ -854,7 +859,7 @@ static void put_pi_state(struct futex_pi_state *pi_state)
* Look up the task based on what TID userspace gave us.
* We dont trust it.
*/
-static struct task_struct * futex_find_get_task(pid_t pid)
+static struct task_struct *futex_find_get_task(pid_t pid)
{
struct task_struct *p;

@@ -916,10 +921,12 @@ void exit_pi_state_list(struct task_struct *curr)
pi_state->owner = NULL;
raw_spin_unlock_irq(&curr->pi_lock);

- rt_mutex_unlock(&pi_state->pi_mutex);
-
+ get_pi_state(pi_state);
spin_unlock(&hb->lock);

+ rt_mutex_futex_unlock(&pi_state->pi_mutex);
+ put_pi_state(pi_state);
+
raw_spin_lock_irq(&curr->pi_lock);
}
raw_spin_unlock_irq(&curr->pi_lock);
@@ -973,6 +980,39 @@ void exit_pi_state_list(struct task_struct *curr)
*
* [10] There is no transient state which leaves owner and user space
* TID out of sync.
+ *
+ *
+ * Serialization and lifetime rules:
+ *
+ * hb->lock:
+ *
+ * hb -> futex_q, relation
+ * futex_q -> pi_state, relation
+ *
+ * (cannot be raw because hb can contain arbitrary amount
+ * of futex_q's)
+ *
+ * pi_mutex->wait_lock:
+ *
+ * {uval, pi_state}
+ *
+ * (and pi_mutex 'obviously')
+ *
+ * p->pi_lock:
+ *
+ * p->pi_state_list -> pi_state->list, relation
+ *
+ * pi_state->refcount:
+ *
+ * pi_state lifetime
+ *
+ *
+ * Lock order:
+ *
+ * hb->lock
+ * pi_mutex->wait_lock
+ * p->pi_lock
+ *
*/

/*
@@ -980,10 +1020,12 @@ void exit_pi_state_list(struct task_struct *curr)
* the pi_state against the user space value. If correct, attach to
* it.
*/
-static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
+static int attach_to_pi_state(u32 __user *uaddr, u32 uval,
+ struct futex_pi_state *pi_state,
struct futex_pi_state **ps)
{
pid_t pid = uval & FUTEX_TID_MASK;
+ int ret, uval2;

/*
* Userspace might have messed up non-PI and PI futexes [3]
@@ -991,9 +1033,39 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
if (unlikely(!pi_state))
return -EINVAL;

+ /*
+ * We get here with hb->lock held, and having found a
+ * futex_top_waiter(). This means that futex_lock_pi() of said futex_q
+ * has dropped the hb->lock in between queue_me() and unqueue_me_pi(),
+ * which in turn means that futex_lock_pi() still has a reference on
+ * our pi_state.
+ *
+ * The waiter holding a reference on @pi_state also protects against
+ * the unlocked put_pi_state() in futex_unlock_pi(), futex_lock_pi()
+ * and futex_wait_requeue_pi() as it cannot go to 0 and consequently
+ * free pi_state before we can take a reference ourselves.
+ */
WARN_ON(!atomic_read(&pi_state->refcount));

/*
+ * Now that we have a pi_state, we can acquire wait_lock
+ * and do the state validation.
+ */
+ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+
+ /*
+ * Since {uval, pi_state} is serialized by wait_lock, and our current
+ * uval was read without holding it, it can have changed. Verify it
+ * still is what we expect it to be, otherwise retry the entire
+ * operation.
+ */
+ if (get_futex_value_locked(&uval2, uaddr))
+ goto out_efault;
+
+ if (uval != uval2)
+ goto out_eagain;
+
+ /*
* Handle the owner died case:
*/
if (uval & FUTEX_OWNER_DIED) {
@@ -1008,11 +1080,11 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
* is not 0. Inconsistent state. [5]
*/
if (pid)
- return -EINVAL;
+ goto out_einval;
/*
* Take a ref on the state and return success. [4]
*/
- goto out_state;
+ goto out_attach;
}

/*
@@ -1024,14 +1096,14 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
* Take a ref on the state and return success. [6]
*/
if (!pid)
- goto out_state;
+ goto out_attach;
} else {
/*
* If the owner died bit is not set, then the pi_state
* must have an owner. [7]
*/
if (!pi_state->owner)
- return -EINVAL;
+ goto out_einval;
}

/*
@@ -1040,11 +1112,29 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
* user space TID. [9/10]
*/
if (pid != task_pid_vnr(pi_state->owner))
- return -EINVAL;
-out_state:
- atomic_inc(&pi_state->refcount);
+ goto out_einval;
+
+out_attach:
+ get_pi_state(pi_state);
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
*ps = pi_state;
return 0;
+
+out_einval:
+ ret = -EINVAL;
+ goto out_error;
+
+out_eagain:
+ ret = -EAGAIN;
+ goto out_error;
+
+out_efault:
+ ret = -EFAULT;
+ goto out_error;
+
+out_error:
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
+ return ret;
}

/*
@@ -1095,6 +1185,9 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key,

/*
* 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();

@@ -1119,17 +1212,18 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key,
return 0;
}

-static int lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
+static int lookup_pi_state(u32 __user *uaddr, u32 uval,
+ struct futex_hash_bucket *hb,
union futex_key *key, struct futex_pi_state **ps)
{
- struct futex_q *match = futex_top_waiter(hb, key);
+ struct futex_q *top_waiter = futex_top_waiter(hb, key);

/*
* If there is a waiter on that futex, validate it and
* attach to the pi_state when the validation succeeds.
*/
- if (match)
- return attach_to_pi_state(uval, match->pi_state, ps);
+ if (top_waiter)
+ return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);

/*
* We are the first waiter - try to look up the owner based on
@@ -1148,7 +1242,7 @@ static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval)
if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)))
return -EFAULT;

- /*If user space value changed, let the caller retry */
+ /* If user space value changed, let the caller retry */
return curval != uval ? -EAGAIN : 0;
}

@@ -1176,7 +1270,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
struct task_struct *task, int set_waiters)
{
u32 uval, newval, vpid = task_pid_vnr(task);
- struct futex_q *match;
+ struct futex_q *top_waiter;
int ret;

/*
@@ -1202,9 +1296,9 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
* Lookup existing state first. If it exists, try to attach to
* its pi_state.
*/
- match = futex_top_waiter(hb, key);
- if (match)
- return attach_to_pi_state(uval, match->pi_state, ps);
+ top_waiter = futex_top_waiter(hb, key);
+ if (top_waiter)
+ return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);

/*
* No waiter and user TID is 0. We are here because the
@@ -1290,46 +1384,39 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q)
* memory barrier is required here to prevent the following
* store to lock_ptr from getting ahead of the plist_del.
*/
- smp_wmb();
- q->lock_ptr = NULL;
+ smp_store_release(&q->lock_ptr, NULL);
}

-static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
- struct futex_hash_bucket *hb)
+/*
+ * Caller must hold a reference on @pi_state.
+ */
+static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_state)
{
- struct task_struct *new_owner;
- struct futex_pi_state *pi_state = this->pi_state;
u32 uninitialized_var(curval), newval;
+ struct task_struct *new_owner;
+ bool deboost = false;
WAKE_Q(wake_q);
WAKE_Q(wake_sleeper_q);
- bool deboost;
int ret = 0;

- if (!pi_state)
- return -EINVAL;
-
- /*
- * If current does not own the pi_state then the futex is
- * inconsistent and user space fiddled with the futex value.
- */
- if (pi_state->owner != current)
- return -EINVAL;
-
- raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
+ if (WARN_ON_ONCE(!new_owner)) {
+ /*
+ * As per the comment in futex_unlock_pi() this should not happen.
+ *
+ * When this happens, give up our locks and try again, giving
+ * the futex_lock_pi() instance time to complete, either by
+ * waiting on the rtmutex or removing itself from the futex
+ * queue.
+ */
+ ret = -EAGAIN;
+ goto out_unlock;
+ }

/*
- * It is possible that the next waiter (the one that brought
- * this owner to the kernel) timed out and is no longer
- * waiting on the lock.
- */
- if (!new_owner)
- new_owner = this->task;
-
- /*
- * We pass it to the next owner. The WAITERS bit is always
- * kept enabled while there is PI state around. We cleanup the
- * owner died bit, because we are the owner.
+ * We pass it to the next owner. The WAITERS bit is always kept
+ * enabled while there is PI state around. We cleanup the owner
+ * died bit, because we are the owner.
*/
newval = FUTEX_WAITERS | task_pid_vnr(new_owner);

@@ -1338,6 +1425,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,

if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) {
ret = -EFAULT;
+
} else if (curval != uval) {
/*
* If a unconditional UNLOCK_PI operation (user space did not
@@ -1350,10 +1438,9 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
else
ret = -EINVAL;
}
- if (ret) {
- raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
- return ret;
- }
+
+ if (ret)
+ goto out_unlock;

raw_spin_lock(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
@@ -1366,24 +1453,22 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
pi_state->owner = new_owner;
raw_spin_unlock(&new_owner->pi_lock);

+ /*
+ * We've updated the uservalue, this unlock cannot fail.
+ */
+ deboost = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q,
+ &wake_sleeper_q);
+
+out_unlock:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);

- deboost = rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q,
- &wake_sleeper_q);
-
- /*
- * First unlock HB so the waiter does not spin on it once he got woken
- * up. Second wake up the waiter before the priority is adjusted. If we
- * deboost first (and lose our higher priority), then the task might get
- * scheduled away before the wake up can take place.
- */
- deboost |= spin_unlock_no_deboost(&hb->lock);
- wake_up_q(&wake_q);
- wake_up_q_sleeper(&wake_sleeper_q);
- if (deboost)
+ if (deboost) {
+ wake_up_q(&wake_q);
+ wake_up_q_sleeper(&wake_sleeper_q);
rt_mutex_adjust_prio(current);
+ }

- return 0;
+ return ret;
}

/*
@@ -1829,7 +1914,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
* If that call succeeds then we have pi_state and an
* initial refcount on it.
*/
- ret = lookup_pi_state(ret, hb2, &key2, &pi_state);
+ ret = lookup_pi_state(uaddr2, ret, hb2, &key2, &pi_state);
}

switch (ret) {
@@ -1912,7 +1997,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
* refcount on the pi_state and store the pointer in
* the futex_q object of the waiter.
*/
- atomic_inc(&pi_state->refcount);
+ get_pi_state(pi_state);
this->pi_state = pi_state;
ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,
this->rt_waiter,
@@ -2022,20 +2107,7 @@ queue_unlock(struct futex_hash_bucket *hb)
hb_waiters_dec(hb);
}

-/**
- * queue_me() - Enqueue the futex_q on the futex_hash_bucket
- * @q: The futex_q to enqueue
- * @hb: The destination hash bucket
- *
- * The hb->lock must be held by the caller, and is released here. A call to
- * queue_me() is typically paired with exactly one call to unqueue_me(). The
- * exceptions involve the PI related operations, which may use unqueue_me_pi()
- * or nothing if the unqueue is done as part of the wake process and the unqueue
- * state is implicit in the state of woken task (see futex_wait_requeue_pi() for
- * an example).
- */
-static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
- __releases(&hb->lock)
+static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
{
int prio;

@@ -2052,6 +2124,24 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
plist_node_init(&q->list, prio);
plist_add(&q->list, &hb->chain);
q->task = current;
+}
+
+/**
+ * queue_me() - Enqueue the futex_q on the futex_hash_bucket
+ * @q: The futex_q to enqueue
+ * @hb: The destination hash bucket
+ *
+ * The hb->lock must be held by the caller, and is released here. A call to
+ * queue_me() is typically paired with exactly one call to unqueue_me(). The
+ * exceptions involve the PI related operations, which may use unqueue_me_pi()
+ * or nothing if the unqueue is done as part of the wake process and the unqueue
+ * state is implicit in the state of woken task (see futex_wait_requeue_pi() for
+ * an example).
+ */
+static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
+ __releases(&hb->lock)
+{
+ __queue_me(q, hb);
spin_unlock(&hb->lock);
}

@@ -2138,10 +2228,13 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
{
u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
struct futex_pi_state *pi_state = q->pi_state;
- struct task_struct *oldowner = pi_state->owner;
u32 uval, uninitialized_var(curval), newval;
+ struct task_struct *oldowner;
int ret;

+ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+
+ oldowner = pi_state->owner;
/* Owner died? */
if (!pi_state->owner)
newtid |= FUTEX_OWNER_DIED;
@@ -2149,7 +2242,8 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
/*
* We are here either because we stole the rtmutex from the
* previous highest priority waiter or we are the highest priority
- * waiter but failed to get the rtmutex the first time.
+ * waiter but have failed to get the rtmutex the first time.
+ *
* We have to replace the newowner TID in the user space variable.
* This must be atomic as we have to preserve the owner died bit here.
*
@@ -2157,17 +2251,16 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
* because we can fault here. Imagine swapped out pages or a fork
* that marked all the anonymous memory readonly for cow.
*
- * Modifying pi_state _before_ the user space value would
- * leave the pi_state in an inconsistent state when we fault
- * here, because we need to drop the hash bucket lock to
- * handle the fault. This might be observed in the PID check
- * in lookup_pi_state.
+ * Modifying pi_state _before_ the user space value would leave the
+ * pi_state in an inconsistent state when we fault here, because we
+ * need to drop the locks to handle the fault. This might be observed
+ * in the PID check in lookup_pi_state.
*/
retry:
if (get_futex_value_locked(&uval, uaddr))
goto handle_fault;

- while (1) {
+ for (;;) {
newval = (uval & FUTEX_OWNER_DIED) | newtid;

if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))
@@ -2182,47 +2275,60 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
* itself.
*/
if (pi_state->owner != NULL) {
- raw_spin_lock_irq(&pi_state->owner->pi_lock);
+ raw_spin_lock(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
- raw_spin_unlock_irq(&pi_state->owner->pi_lock);
+ raw_spin_unlock(&pi_state->owner->pi_lock);
}

pi_state->owner = newowner;

- raw_spin_lock_irq(&newowner->pi_lock);
+ raw_spin_lock(&newowner->pi_lock);
WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &newowner->pi_state_list);
- raw_spin_unlock_irq(&newowner->pi_lock);
+ raw_spin_unlock(&newowner->pi_lock);
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
+
return 0;

/*
- * To handle the page fault we need to drop the hash bucket
- * lock here. That gives the other task (either the highest priority
- * waiter itself or the task which stole the rtmutex) the
- * chance to try the fixup of the pi_state. So once we are
- * back from handling the fault we need to check the pi_state
- * after reacquiring the hash bucket lock and before trying to
- * do another fixup. When the fixup has been done already we
- * simply return.
+ * To handle the page fault we need to drop the locks here. That gives
+ * the other task (either the highest priority waiter itself or the
+ * task which stole the rtmutex) the chance to try the fixup of the
+ * pi_state. So once we are back from handling the fault we need to
+ * check the pi_state after reacquiring the locks and before trying to
+ * do another fixup. When the fixup has been done already we simply
+ * return.
+ *
+ * Note: we hold both hb->lock and pi_mutex->wait_lock. We can safely
+ * drop hb->lock since the caller owns the hb -> futex_q relation.
+ * Dropping the pi_mutex->wait_lock requires the state revalidate.
*/
handle_fault:
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
spin_unlock(q->lock_ptr);

ret = fault_in_user_writeable(uaddr);

spin_lock(q->lock_ptr);
+ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);

/*
* Check if someone else fixed it for us:
*/
- if (pi_state->owner != oldowner)
- return 0;
+ if (pi_state->owner != oldowner) {
+ ret = 0;
+ goto out_unlock;
+ }

if (ret)
- return ret;
+ goto out_unlock;

goto retry;
+
+out_unlock:
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
+ return ret;
}

static long futex_wait_restart(struct restart_block *restart);
@@ -2244,13 +2350,16 @@ static long futex_wait_restart(struct restart_block *restart);
*/
static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked)
{
- struct task_struct *owner;
int ret = 0;

if (locked) {
/*
* Got the lock. We might not be the anticipated owner if we
* did a lock-steal - fix up the PI-state in that case:
+ *
+ * We can safely read pi_state->owner without holding wait_lock
+ * because we now own the rt_mutex, only the owner will attempt
+ * to change it.
*/
if (q->pi_state->owner != current)
ret = fixup_pi_state_owner(uaddr, q, current);
@@ -2258,43 +2367,15 @@ static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked)
}

/*
- * Catch the rare case, where the lock was released when we were on the
- * way back before we locked the hash bucket.
- */
- if (q->pi_state->owner == current) {
- /*
- * Try to get the rt_mutex now. This might fail as some other
- * task acquired the rt_mutex after we removed ourself from the
- * rt_mutex waiters list.
- */
- if (rt_mutex_trylock(&q->pi_state->pi_mutex)) {
- locked = 1;
- goto out;
- }
-
- /*
- * pi_state is incorrect, some other task did a lock steal and
- * we returned due to timeout or signal without taking the
- * rt_mutex. Too late.
- */
- raw_spin_lock_irq(&q->pi_state->pi_mutex.wait_lock);
- owner = rt_mutex_owner(&q->pi_state->pi_mutex);
- if (!owner)
- owner = rt_mutex_next_owner(&q->pi_state->pi_mutex);
- raw_spin_unlock_irq(&q->pi_state->pi_mutex.wait_lock);
- ret = fixup_pi_state_owner(uaddr, q, owner);
- goto out;
- }
-
- /*
* Paranoia check. If we did not take the lock, then we should not be
* the owner of the rt_mutex.
*/
- if (rt_mutex_owner(&q->pi_state->pi_mutex) == current)
+ if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) {
printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p "
"pi-state %p\n", ret,
q->pi_state->pi_mutex.owner,
q->pi_state->owner);
+ }

out:
return ret ? ret : locked;
@@ -2518,6 +2599,8 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
ktime_t *time, int trylock)
{
struct hrtimer_sleeper timeout, *to = NULL;
+ struct futex_pi_state *pi_state = NULL;
+ struct rt_mutex_waiter rt_waiter;
struct futex_hash_bucket *hb;
struct futex_q q = futex_q_init;
int res, ret;
@@ -2570,25 +2653,77 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
}
}

+ WARN_ON(!q.pi_state);
+
/*
* Only actually queue now that the atomic ops are done:
*/
- queue_me(&q, hb);
+ __queue_me(&q, hb);

- WARN_ON(!q.pi_state);
- /*
- * Block on the PI mutex:
- */
- if (!trylock) {
- ret = rt_mutex_timed_futex_lock(&q.pi_state->pi_mutex, to);
- } else {
- ret = rt_mutex_trylock(&q.pi_state->pi_mutex);
+ if (trylock) {
+ ret = rt_mutex_futex_trylock(&q.pi_state->pi_mutex);
/* Fixup the trylock return value: */
ret = ret ? 0 : -EWOULDBLOCK;
+ goto no_block;
}

+ rt_mutex_init_waiter(&rt_waiter, false);
+
+ /*
+ * On PREEMPT_RT_FULL, when hb->lock becomes an rt_mutex, we must not
+ * hold it while doing rt_mutex_start_proxy(), because then it will
+ * include hb->lock in the blocking chain, even through we'll not in
+ * fact hold it while blocking. This will lead it to report -EDEADLK
+ * and BUG when futex_unlock_pi() interleaves with this.
+ *
+ * Therefore acquire wait_lock while holding hb->lock, but drop the
+ * latter before calling rt_mutex_start_proxy_lock(). This still fully
+ * serializes against futex_unlock_pi() as that does the exact same
+ * lock handoff sequence.
+ */
+ raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock);
+ /*
+ * the migrate_disable() here disables migration in the in_atomic() fast
+ * path which is enabled again in the following spin_unlock(). We have
+ * one migrate_disable() pending in the slow-path which is reversed
+ * after the raw_spin_unlock_irq() where we leave the atomic context.
+ */
+ migrate_disable();
+
+ spin_unlock(q.lock_ptr);
+ ret = __rt_mutex_start_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter, current);
+ raw_spin_unlock_irq(&q.pi_state->pi_mutex.wait_lock);
+ migrate_enable();
+
+ if (ret) {
+ if (ret == 1)
+ ret = 0;
+
+ spin_lock(q.lock_ptr);
+ goto no_block;
+ }
+
+
+ if (unlikely(to))
+ hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS);
+
+ ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter);
+
spin_lock(q.lock_ptr);
/*
+ * If we failed to acquire the lock (signal/timeout), we must
+ * first acquire the hb->lock before removing the lock from the
+ * rt_mutex waitqueue, such that we can keep the hb and rt_mutex
+ * wait lists consistent.
+ *
+ * In particular; it is important that futex_unlock_pi() can not
+ * observe this inconsistency.
+ */
+ if (ret && !rt_mutex_cleanup_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter))
+ ret = 0;
+
+no_block:
+ /*
* Fixup the pi_state owner and possibly acquire the lock if we
* haven't already.
*/
@@ -2604,12 +2739,19 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
* If fixup_owner() faulted and was unable to handle the fault, unlock
* it and return the fault to userspace.
*/
- if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current))
- rt_mutex_unlock(&q.pi_state->pi_mutex);
+ if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) {
+ pi_state = q.pi_state;
+ get_pi_state(pi_state);
+ }

/* Unqueue and drop the lock */
unqueue_me_pi(&q);

+ if (pi_state) {
+ rt_mutex_futex_unlock(&pi_state->pi_mutex);
+ put_pi_state(pi_state);
+ }
+
goto out_put_key;

out_unlock_put_key:
@@ -2646,7 +2788,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
u32 uninitialized_var(curval), uval, vpid = task_pid_vnr(current);
union futex_key key = FUTEX_KEY_INIT;
struct futex_hash_bucket *hb;
- struct futex_q *match;
+ struct futex_q *top_waiter;
int ret;

retry:
@@ -2670,12 +2812,48 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
* all and we at least want to know if user space fiddled
* with the futex value instead of blindly unlocking.
*/
- match = futex_top_waiter(hb, &key);
- if (match) {
- ret = wake_futex_pi(uaddr, uval, match, hb);
+ top_waiter = futex_top_waiter(hb, &key);
+ if (top_waiter) {
+ struct futex_pi_state *pi_state = top_waiter->pi_state;
+
+ ret = -EINVAL;
+ if (!pi_state)
+ goto out_unlock;
+
/*
- * In case of success wake_futex_pi dropped the hash
- * bucket lock.
+ * If current does not own the pi_state then the futex is
+ * inconsistent and user space fiddled with the futex value.
+ */
+ if (pi_state->owner != current)
+ goto out_unlock;
+
+ get_pi_state(pi_state);
+ /*
+ * By taking wait_lock while still holding hb->lock, we ensure
+ * there is no point where we hold neither; and therefore
+ * wake_futex_pi() must observe a state consistent with what we
+ * observed.
+ */
+ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+ /*
+ * Magic trickery for now to make the RT migrate disable
+ * logic happy. The following spin_unlock() happens with
+ * interrupts disabled so the internal migrate_enable()
+ * won't undo the migrate_disable() which was issued when
+ * locking hb->lock.
+ */
+ migrate_disable();
+ spin_unlock(&hb->lock);
+
+ /* Drops pi_state->pi_mutex.wait_lock */
+ ret = wake_futex_pi(uaddr, uval, pi_state);
+
+ migrate_enable();
+
+ put_pi_state(pi_state);
+
+ /*
+ * Success, we're done! No tricky corner cases.
*/
if (!ret)
goto out_putkey;
@@ -2690,7 +2868,6 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
* setting the FUTEX_WAITERS bit. Try again.
*/
if (ret == -EAGAIN) {
- spin_unlock(&hb->lock);
put_futex_key(&key);
goto retry;
}
@@ -2698,7 +2875,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
* wake_futex_pi has detected invalid state. Tell user
* space.
*/
- goto out_unlock;
+ goto out_putkey;
}

/*
@@ -2708,8 +2885,10 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
* preserve the WAITERS bit not the OWNER_DIED one. We are the
* owner.
*/
- if (cmpxchg_futex_value_locked(&curval, uaddr, uval, 0))
+ if (cmpxchg_futex_value_locked(&curval, uaddr, uval, 0)) {
+ spin_unlock(&hb->lock);
goto pi_faulted;
+ }

/*
* If uval has changed, let user space handle it.
@@ -2723,7 +2902,6 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
return ret;

pi_faulted:
- spin_unlock(&hb->lock);
put_futex_key(&key);

ret = fault_in_user_writeable(uaddr);
@@ -2827,6 +3005,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
u32 __user *uaddr2)
{
struct hrtimer_sleeper timeout, *to = NULL;
+ struct futex_pi_state *pi_state = NULL;
struct rt_mutex_waiter rt_waiter;
struct futex_hash_bucket *hb, *hb2;
union futex_key key2 = FUTEX_KEY_INIT;
@@ -2944,8 +3123,10 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
spin_lock(&hb2->lock);
BUG_ON(&hb2->lock != q.lock_ptr);
ret = fixup_pi_state_owner(uaddr2, &q, current);
- if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current)
- rt_mutex_unlock(&q.pi_state->pi_mutex);
+ if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) {
+ pi_state = q.pi_state;
+ get_pi_state(pi_state);
+ }
/*
* Drop the reference to the pi state which
* the requeue_pi() code acquired for us.
@@ -2963,11 +3144,14 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
*/
WARN_ON(!q.pi_state);
pi_mutex = &q.pi_state->pi_mutex;
- ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter);
- debug_rt_mutex_free_waiter(&rt_waiter);
+ ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter);

spin_lock(&hb2->lock);
BUG_ON(&hb2->lock != q.lock_ptr);
+ if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter))
+ ret = 0;
+
+ debug_rt_mutex_free_waiter(&rt_waiter);
/*
* Fixup the pi_state owner and possibly acquire the lock if we
* haven't already.
@@ -2985,13 +3169,20 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
* the fault, unlock the rt_mutex and return the fault to
* userspace.
*/
- if (ret && rt_mutex_owner(pi_mutex) == current)
- rt_mutex_unlock(pi_mutex);
+ if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) {
+ pi_state = q.pi_state;
+ get_pi_state(pi_state);
+ }

/* Unqueue and drop the lock. */
unqueue_me_pi(&q);
}

+ if (pi_state) {
+ rt_mutex_futex_unlock(&pi_state->pi_mutex);
+ put_pi_state(pi_state);
+ }
+
if (ret == -EINTR) {
/*
* We've already been requeued, but cannot restart by calling
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
--- a/kernel/locking/rtmutex-debug.c
+++ b/kernel/locking/rtmutex-debug.c
@@ -173,12 +173,3 @@ void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
lock->name = name;
}

-void
-rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
-{
-}
-
-void rt_mutex_deadlock_account_unlock(struct task_struct *task)
-{
-}
-
diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
--- a/kernel/locking/rtmutex-debug.h
+++ b/kernel/locking/rtmutex-debug.h
@@ -9,9 +9,6 @@
* This file contains macros used solely by rtmutex.c. Debug version.
*/

-extern void
-rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task);
-extern void rt_mutex_deadlock_account_unlock(struct task_struct *task);
extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -978,8 +978,6 @@ static int __try_to_take_rt_mutex(struct rt_mutex *lock,
*/
rt_mutex_set_owner(lock, task);

- rt_mutex_deadlock_account_lock(lock, task);
-
return 1;
}

@@ -998,19 +996,18 @@ static inline void rt_spin_lock_fastlock(struct rt_mutex *lock,
migrate_disable();

if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
- rt_mutex_deadlock_account_lock(lock, current);
+ return;
else
slowfn(lock, do_mig_dis);
}

-static inline int rt_spin_lock_fastunlock(struct rt_mutex *lock,
- int (*slowfn)(struct rt_mutex *lock))
+static inline void rt_spin_lock_fastunlock(struct rt_mutex *lock,
+ void (*slowfn)(struct rt_mutex *lock))
{
- if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) {
- rt_mutex_deadlock_account_unlock(current);
- return 0;
- }
- return slowfn(lock);
+ if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
+ return;
+ else
+ slowfn(lock);
}
#ifdef CONFIG_SMP
/*
@@ -1151,7 +1148,7 @@ static void mark_wakeup_next_waiter(struct wake_q_head *wake_q,
/*
* Slow path to release a rt_mutex spin_lock style
*/
-static int noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
+static void noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
{
unsigned long flags;
WAKE_Q(wake_q);
@@ -1161,12 +1158,10 @@ static int noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)

debug_rt_mutex_unlock(lock);

- rt_mutex_deadlock_account_unlock(current);
-
if (!rt_mutex_has_waiters(lock)) {
lock->owner = NULL;
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
- return 0;
+ return;
}

mark_wakeup_next_waiter(&wake_q, &wake_sleeper_q, lock);
@@ -1177,33 +1172,6 @@ static int noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)

/* Undo pi boosting.when necessary */
rt_mutex_adjust_prio(current);
- return 0;
-}
-
-static int noinline __sched rt_spin_lock_slowunlock_no_deboost(struct rt_mutex *lock)
-{
- unsigned long flags;
- WAKE_Q(wake_q);
- WAKE_Q(wake_sleeper_q);
-
- raw_spin_lock_irqsave(&lock->wait_lock, flags);
-
- debug_rt_mutex_unlock(lock);
-
- rt_mutex_deadlock_account_unlock(current);
-
- if (!rt_mutex_has_waiters(lock)) {
- lock->owner = NULL;
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
- return 0;
- }
-
- mark_wakeup_next_waiter(&wake_q, &wake_sleeper_q, lock);
-
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
- wake_up_q(&wake_q);
- wake_up_q_sleeper(&wake_sleeper_q);
- return 1;
}

void __lockfunc rt_spin_lock__no_mg(spinlock_t *lock)
@@ -1258,17 +1226,6 @@ void __lockfunc rt_spin_unlock(spinlock_t *lock)
}
EXPORT_SYMBOL(rt_spin_unlock);

-int __lockfunc rt_spin_unlock_no_deboost(spinlock_t *lock)
-{
- int ret;
-
- /* NOTE: we always pass in '1' for nested, for simplicity */
- spin_release(&lock->dep_map, 1, _RET_IP_);
- ret = rt_spin_lock_fastunlock(&lock->lock, rt_spin_lock_slowunlock_no_deboost);
- migrate_enable();
- return ret;
-}
-
void __lockfunc __rt_spin_unlock(struct rt_mutex *lock)
{
rt_spin_lock_fastunlock(lock, rt_spin_lock_slowunlock);
@@ -1644,6 +1601,15 @@ void rt_mutex_adjust_pi(struct task_struct *task)
next_lock, NULL, task);
}

+void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter, bool savestate)
+{
+ debug_rt_mutex_init_waiter(waiter);
+ RB_CLEAR_NODE(&waiter->pi_tree_entry);
+ RB_CLEAR_NODE(&waiter->tree_entry);
+ waiter->task = NULL;
+ waiter->savestate = savestate;
+}
+
/**
* __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
* @lock: the rt_mutex to take
@@ -1926,8 +1892,6 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,

debug_rt_mutex_unlock(lock);

- rt_mutex_deadlock_account_unlock(current);
-
/*
* We must be careful here if the fast path is enabled. If we
* have no waiters queued we cannot set owner to NULL here
@@ -1995,12 +1959,10 @@ rt_mutex_fastlock(struct rt_mutex *lock, int state,
enum rtmutex_chainwalk chwalk,
struct ww_acquire_ctx *ww_ctx))
{
- if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) {
- rt_mutex_deadlock_account_lock(lock, current);
+ if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
- } else
- return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK,
- ww_ctx);
+
+ return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK, ww_ctx);
}

static inline int
@@ -2014,21 +1976,19 @@ rt_mutex_timed_fastlock(struct rt_mutex *lock, int state,
struct ww_acquire_ctx *ww_ctx))
{
if (chwalk == RT_MUTEX_MIN_CHAINWALK &&
- likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) {
- rt_mutex_deadlock_account_lock(lock, current);
+ likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
- } else
- return slowfn(lock, state, timeout, chwalk, ww_ctx);
+
+ return slowfn(lock, state, timeout, chwalk, ww_ctx);
}

static inline int
rt_mutex_fasttrylock(struct rt_mutex *lock,
int (*slowfn)(struct rt_mutex *lock))
{
- if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) {
- rt_mutex_deadlock_account_lock(lock, current);
+ if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 1;
- }
+
return slowfn(lock);
}

@@ -2040,20 +2000,19 @@ rt_mutex_fastunlock(struct rt_mutex *lock,
{
WAKE_Q(wake_q);
WAKE_Q(wake_sleeper_q);
+ bool deboost;

- if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) {
- rt_mutex_deadlock_account_unlock(current);
+ if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
+ return;

- } else {
- bool deboost = slowfn(lock, &wake_q, &wake_sleeper_q);
+ deboost = slowfn(lock, &wake_q, &wake_sleeper_q);

- wake_up_q(&wake_q);
- wake_up_q_sleeper(&wake_sleeper_q);
+ wake_up_q(&wake_q);
+ wake_up_q_sleeper(&wake_sleeper_q);

- /* Undo pi boosting if necessary: */
- if (deboost)
- rt_mutex_adjust_prio(current);
- }
+ /* Undo pi boosting if necessary: */
+ if (deboost)
+ rt_mutex_adjust_prio(current);
}

/**
@@ -2087,16 +2046,11 @@ int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);

/*
- * Futex variant with full deadlock detection.
+ * Futex variant, must not use fastpath.
*/
-int rt_mutex_timed_futex_lock(struct rt_mutex *lock,
- struct hrtimer_sleeper *timeout)
+int __sched rt_mutex_futex_trylock(struct rt_mutex *lock)
{
- might_sleep();
-
- return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
- RT_MUTEX_FULL_CHAINWALK, NULL,
- rt_mutex_slowlock);
+ return rt_mutex_slowtrylock(lock);
}

/**
@@ -2179,21 +2133,41 @@ void __sched rt_mutex_unlock(struct rt_mutex *lock)
EXPORT_SYMBOL_GPL(rt_mutex_unlock);

/**
- * rt_mutex_futex_unlock - Futex variant of rt_mutex_unlock
- * @lock: the rt_mutex to be unlocked
- *
- * Returns: true/false indicating whether priority adjustment is
- * required or not.
+ * Futex variant, that since futex variants do not use the fast-path, can be
+ * simple and will not need to retry.
*/
-bool __sched rt_mutex_futex_unlock(struct rt_mutex *lock,
- struct wake_q_head *wqh,
- struct wake_q_head *wq_sleeper)
+bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
+ struct wake_q_head *wake_q,
+ struct wake_q_head *wq_sleeper)
{
- if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) {
- rt_mutex_deadlock_account_unlock(current);
- return false;
+ lockdep_assert_held(&lock->wait_lock);
+
+ debug_rt_mutex_unlock(lock);
+
+ if (!rt_mutex_has_waiters(lock)) {
+ lock->owner = NULL;
+ return false; /* done */
+ }
+
+ mark_wakeup_next_waiter(wake_q, wq_sleeper, lock);
+ return true; /* deboost and wakeups */
+}
+
+void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
+{
+ WAKE_Q(wake_q);
+ WAKE_Q(wake_sleeper_q);
+ bool deboost;
+
+ raw_spin_lock_irq(&lock->wait_lock);
+ deboost = __rt_mutex_futex_unlock(lock, &wake_q, &wake_sleeper_q);
+ raw_spin_unlock_irq(&lock->wait_lock);
+
+ if (deboost) {
+ wake_up_q(&wake_q);
+ wake_up_q_sleeper(&wake_sleeper_q);
+ rt_mutex_adjust_prio(current);
}
- return rt_mutex_slowunlock(lock, wqh, wq_sleeper);
}

/**
@@ -2249,7 +2223,6 @@ void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
rt_mutex_init(lock);
debug_rt_mutex_proxy_lock(lock, proxy_owner);
rt_mutex_set_owner(lock, proxy_owner);
- rt_mutex_deadlock_account_lock(lock, proxy_owner);
}

/**
@@ -2265,34 +2238,16 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock,
{
debug_rt_mutex_proxy_unlock(lock);
rt_mutex_set_owner(lock, NULL);
- rt_mutex_deadlock_account_unlock(proxy_owner);
}

-/**
- * 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
- *
- * 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.
- */
-int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task)
{
int ret;

- raw_spin_lock_irq(&lock->wait_lock);
-
- if (try_to_take_rt_mutex(lock, task, NULL)) {
- raw_spin_unlock_irq(&lock->wait_lock);
+ if (try_to_take_rt_mutex(lock, task, NULL))
return 1;
- }

#ifdef CONFIG_PREEMPT_RT_FULL
/*
@@ -2340,14 +2295,38 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
if (ret && rt_mutex_has_waiters(lock))
remove_waiter(lock, waiter);

- raw_spin_unlock_irq(&lock->wait_lock);
-
debug_rt_mutex_print_deadlock(waiter);

return ret;
}

/**
+ * 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
+ *
+ * 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.
+ */
+int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *task)
+{
+ int ret;
+
+ raw_spin_lock_irq(&lock->wait_lock);
+ ret = __rt_mutex_start_proxy_lock(lock, waiter, task);
+ raw_spin_unlock_irq(&lock->wait_lock);
+
+ return ret;
+}
+
+/**
* rt_mutex_next_owner - return the next owner of the lock
*
* @lock: the rt lock query
@@ -2368,21 +2347,23 @@ struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
}

/**
- * rt_mutex_finish_proxy_lock() - Complete lock acquisition
+ * rt_mutex_wait_proxy_lock() - Wait for lock acquisition
* @lock: the rt_mutex we were woken on
* @to: the timeout, null if none. hrtimer should already have
* been started.
* @waiter: the pre-initialized rt_mutex_waiter
*
- * Complete the lock acquisition started our behalf by another thread.
+ * Wait for the the lock acquisition started on our behalf by
+ * rt_mutex_start_proxy_lock(). Upon failure, the caller must call
+ * rt_mutex_cleanup_proxy_lock().
*
* Returns:
* 0 - success
* <0 - error, one of -EINTR, -ETIMEDOUT
*
- * Special API call for PI-futex requeue support
+ * Special API call for PI-futex support
*/
-int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
struct hrtimer_sleeper *to,
struct rt_mutex_waiter *waiter)
{
@@ -2395,8 +2376,45 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
/* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter, NULL);

- if (unlikely(ret))
+ raw_spin_unlock_irq(&lock->wait_lock);
+
+ return ret;
+}
+
+/**
+ * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
+ * @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().
+ *
+ * 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
+ * find we are in fact the owner and must disregard the
+ * rt_mutex_wait_proxy_lock() failure.
+ *
+ * Returns:
+ * true - did the cleanup, we done.
+ * false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
+ * caller should disregards its return value.
+ *
+ * Special API call for PI-futex support
+ */
+bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter)
+{
+ bool cleanup = false;
+
+ raw_spin_lock_irq(&lock->wait_lock);
+ /*
+ * Unless we're the owner; we're still enqueued on the wait_list.
+ * So check if we became owner, if not, take us off the wait_list.
+ */
+ if (rt_mutex_owner(lock) != current) {
remove_waiter(lock, waiter);
+ fixup_rt_mutex_waiters(lock);
+ cleanup = true;
+ }

/*
* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
@@ -2406,7 +2424,7 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,

raw_spin_unlock_irq(&lock->wait_lock);

- return ret;
+ return cleanup;
}

static inline int
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
--- a/kernel/locking/rtmutex.h
+++ b/kernel/locking/rtmutex.h
@@ -11,8 +11,6 @@
*/

#define rt_mutex_deadlock_check(l) (0)
-#define rt_mutex_deadlock_account_lock(m, t) do { } while (0)
-#define rt_mutex_deadlock_account_unlock(l) do { } while (0)
#define debug_rt_mutex_init_waiter(w) do { } while (0)
#define debug_rt_mutex_free_waiter(w) do { } while (0)
#define debug_rt_mutex_lock(l) do { } while (0)
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -107,16 +107,26 @@ extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
struct task_struct *proxy_owner);
+extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter, bool savetate);
+extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *task);
extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task);
-extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
- struct hrtimer_sleeper *to,
- struct rt_mutex_waiter *waiter);
-extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
-extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
- struct wake_q_head *wqh,
- struct wake_q_head *wq_sleeper);
+extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
+ struct hrtimer_sleeper *to,
+ struct rt_mutex_waiter *waiter);
+extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter);
+
+extern int rt_mutex_futex_trylock(struct rt_mutex *l);
+
+extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
+extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
+ struct wake_q_head *wqh,
+ struct wake_q_head *wq_sleeper);
+
extern void rt_mutex_adjust_prio(struct task_struct *task);

#ifdef CONFIG_DEBUG_RT_MUTEXES
@@ -125,14 +135,4 @@ extern void rt_mutex_adjust_prio(struct task_struct *task);
# include "rtmutex.h"
#endif

-static inline void
-rt_mutex_init_waiter(struct rt_mutex_waiter *waiter, bool savestate)
-{
- debug_rt_mutex_init_waiter(waiter);
- waiter->task = NULL;
- waiter->savestate = savestate;
- RB_CLEAR_NODE(&waiter->pi_tree_entry);
- RB_CLEAR_NODE(&waiter->tree_entry);
-}
-
#endif
diff --git a/kernel/module.c b/kernel/module.c
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -677,8 +677,12 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
void *va = (void *)addr;

if (va >= start && va < start + mod->percpu_size) {
- if (can_addr)
+ if (can_addr) {
*can_addr = (unsigned long) (va - start);
+ *can_addr += (unsigned long)
+ per_cpu_ptr(mod->percpu,
+ get_boot_cpu_id());
+ }
preempt_enable();
return true;
}
diff --git a/localversion-rt b/localversion-rt
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt13
+-rt14
diff --git a/mm/percpu.c b/mm/percpu.c
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1295,8 +1295,11 @@ bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
void *va = (void *)addr;

if (va >= start && va < start + static_size) {
- if (can_addr)
+ if (can_addr) {
*can_addr = (unsigned long) (va - start);
+ *can_addr += (unsigned long)
+ per_cpu_ptr(base, get_boot_cpu_id());
+ }
return true;
}
}
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