locking/rtmutex: Use the 'struct' keyword in kernel-doc comment

Add the "struct" keyword to prevent a kernel-doc warning:

rtmutex_common.h:67: warning: cannot understand function prototype: 'stru

locking/rtmutex: Use the 'struct' keyword in kernel-doc comment

Add the "struct" keyword to prevent a kernel-doc warning:

rtmutex_common.h:67: warning: cannot understand function prototype: 'struct rt_wake_q_head '

Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Waiman Long <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/mutex: Remove wakeups from under mutex::wait_lock

In preparation to nest mutex::wait_lock under rq::lock we need
to remove wakeups from under it.

Do this by utilizing wake_qs to defer the w

locking/mutex: Remove wakeups from under mutex::wait_lock

In preparation to nest mutex::wait_lock under rq::lock we need
to remove wakeups from under it.

Do this by utilizing wake_qs to defer the wakeup until after the
lock is dropped.

[Heavily changed after 55f036ca7e74 ("locking: WW mutex cleanup") and
08295b3b5bee ("locking: Implement an algorithm choice for Wound-Wait
mutexes")]
[jstultz: rebased to mainline, added extra wake_up_q & init
to avoid hangs, similar to Connor's rework of this patch]

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Juri Lelli <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Metin Kaya <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Tested-by: K Prateek Nayak <[email protected]>
Tested-by: Metin Kaya <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Fix task->pi_waiters integrity

Henry reported that rt_mutex_adjust_prio_check() has an ordering
problem and puts the lie to the comment in [7]. Sharing the sort key
between lock->wa

locking/rtmutex: Fix task->pi_waiters integrity

Henry reported that rt_mutex_adjust_prio_check() has an ordering
problem and puts the lie to the comment in [7]. Sharing the sort key
between lock->waiters and owner->pi_waiters *does* create problems,
since unlike what the comment claims, holding [L] is insufficient.

Notably, consider:

A
/ \
M1 M2
| |
B C

That is, task A owns both M1 and M2, B and C block on them. In this
case a concurrent chain walk (B & C) will modify their resp. sort keys
in [7] while holding M1->wait_lock and M2->wait_lock. So holding [L]
is meaningless, they're different Ls.

This then gives rise to a race condition between [7] and [11], where
the requeue of pi_waiters will observe an inconsistent tree order.

B C

(holds M1->wait_lock, (holds M2->wait_lock,
holds B->pi_lock) holds A->pi_lock)

[7]
waiter_update_prio();
...
[8]
raw_spin_unlock(B->pi_lock);
...
[10]
raw_spin_lock(A->pi_lock);

[11]
rt_mutex_enqueue_pi();
// observes inconsistent A->pi_waiters
// tree order

Fixing this means either extending the range of the owner lock from
[10-13] to [6-13], with the immediate problem that this means [6-8]
hold both blocked and owner locks, or duplicating the sort key.

Since the locking in chain walk is horrible enough without having to
consider pi_lock nesting rules, duplicate the sort key instead.

By giving each tree their own sort key, the above race becomes
harmless, if C sees B at the old location, then B will correct things
(if they need correcting) when it walks up the chain and reaches A.

Fixes: fb00aca47440 ("rtmutex: Turn the plist into an rb-tree")
Reported-by: Henry Wu <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Tested-by: Henry Wu <[email protected]>
Link: https://lkml.kernel.org/r/20230707161052.GF2883469%40hirez.programming.kicks-ass.net

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locking/rtmutex: Dont dereference waiter lockless

The new rt_mutex_spin_on_onwer() loop checks whether the spinning waiter is
still the top waiter on the lock by utilizing rt_mutex_top_waiter(), whi

locking/rtmutex: Dont dereference waiter lockless

The new rt_mutex_spin_on_onwer() loop checks whether the spinning waiter is
still the top waiter on the lock by utilizing rt_mutex_top_waiter(), which
is broken because that function contains a sanity check which dereferences
the top waiter pointer to check whether the waiter belongs to the
lock. That's wrong in the lockless spinwait case:

CPU 0 CPU 1
rt_mutex_lock(lock) rt_mutex_lock(lock);
queue(waiter0)
waiter0 == rt_mutex_top_waiter(lock)
rt_mutex_spin_on_onwer(lock, waiter0) { queue(waiter1)
waiter1 == rt_mutex_top_waiter(lock)
...
top_waiter = rt_mutex_top_waiter(lock)
leftmost = rb_first_cached(&lock->waiters);
-> signal
dequeue(waiter1)
destroy(waiter1)
w = rb_entry(leftmost, ....)
BUG_ON(w->lock != lock) <- UAF

The BUG_ON() is correct for the case where the caller holds lock->wait_lock
which guarantees that the leftmost waiter entry cannot vanish. For the
lockless spinwait case it's broken.

Create a new helper function which avoids the pointer dereference and just
compares the leftmost entry pointer with current's waiter pointer to
validate that currrent is still elegible for spinning.

Fixes: 992caf7f1724 ("locking/rtmutex: Add adaptive spinwait mechanism")
Reported-by: Sebastian Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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locking/rtmutex: Extend the rtmutex core to support ww_mutex

Add a ww acquire context pointer to the waiter and various functions and
add the ww_mutex related invocations to the proper spots in the

locking/rtmutex: Extend the rtmutex core to support ww_mutex

Add a ww acquire context pointer to the waiter and various functions and
add the ww_mutex related invocations to the proper spots in the locking
code, similar to the mutex based variant.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Provide the spin/rwlock core lock function

A simplified version of the rtmutex slowlock function, which neither handles
signals nor timeouts, and is careful about preserving the sta

locking/rtmutex: Provide the spin/rwlock core lock function

A simplified version of the rtmutex slowlock function, which neither handles
signals nor timeouts, and is careful about preserving the state of the
blocked task across the lock operation.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Prepare RT rt_mutex_wake_q for RT locks

Add an rtlock_task pointer to rt_mutex_wake_q, which allows to handle the RT
specific wakeup for spin/rwlock waiters. The pointer is just con

locking/rtmutex: Prepare RT rt_mutex_wake_q for RT locks

Add an rtlock_task pointer to rt_mutex_wake_q, which allows to handle the RT
specific wakeup for spin/rwlock waiters. The pointer is just consuming 4/8
bytes on the stack so it is provided unconditionaly to avoid #ifdeffery all
over the place.

This cannot use a regular wake_q, because a task can have concurrent wakeups which
would make it miss either lock or the regular wakeups, depending on what gets
queued first, unless task struct gains a separate wake_q_node for this, which
would be overkill, because there can only be a single task which gets woken
up in the spin/rw_lock unlock path.

No functional change for non-RT enabled kernels.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Use rt_mutex_wake_q_head

Prepare for the required state aware handling of waiter wakeups via wake_q
and switch the rtmutex code over to the rtmutex specific wrapper.

No functional

locking/rtmutex: Use rt_mutex_wake_q_head

Prepare for the required state aware handling of waiter wakeups via wake_q
and switch the rtmutex code over to the rtmutex specific wrapper.

No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Provide rt_wake_q_head and helpers

To handle the difference between wakeups for regular sleeping locks (mutex,
rtmutex, rw_semaphore) and the wakeups for 'sleeping' spin/rwlocks on

locking/rtmutex: Provide rt_wake_q_head and helpers

To handle the difference between wakeups for regular sleeping locks (mutex,
rtmutex, rw_semaphore) and the wakeups for 'sleeping' spin/rwlocks on
PREEMPT_RT enabled kernels correctly, it is required to provide a
wake_q_head construct which allows to keep them separate.

Provide a wrapper around wake_q_head and the required helpers, which will be
extended with the state handling later.

No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Add wake_state to rt_mutex_waiter

Regular sleeping locks like mutexes, rtmutexes and rw_semaphores are always
entering and leaving a blocking section with task state == TASK_RUNNING

locking/rtmutex: Add wake_state to rt_mutex_waiter

Regular sleeping locks like mutexes, rtmutexes and rw_semaphores are always
entering and leaving a blocking section with task state == TASK_RUNNING.

On a non-RT kernel spinlocks and rwlocks never affect the task state, but
on RT kernels these locks are converted to rtmutex based 'sleeping' locks.

So in case of contention the task goes to block, which requires to carefully
preserve the task state, and restore it after acquiring the lock taking
regular wakeups for the task into account, which happened while the task was
blocked. This state preserving is achieved by having a separate task state
for blocking on a RT spin/rwlock and a saved_state field in task_struct
along with careful handling of these wakeup scenarios in try_to_wake_up().

To avoid conditionals in the rtmutex code, store the wake state which has
to be used for waking a lock waiter in rt_mutex_waiter which allows to
handle the regular and RT spin/rwlocks by handing it to wake_up_state().

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Split out the inner parts of 'struct rtmutex'

RT builds substitutions for rwsem, mutex, spinlock and rwlock around
rtmutexes. Split the inner working out so each lock substitution c

locking/rtmutex: Split out the inner parts of 'struct rtmutex'

RT builds substitutions for rwsem, mutex, spinlock and rwlock around
rtmutexes. Split the inner working out so each lock substitution can use
them with the appropriate lockdep annotations. This avoids having an extra
unused lockdep map in the wrapped rtmutex.

No functional change.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Split API from implementation

Prepare for reusing the inner functions of rtmutex for RT lock
substitutions: introduce kernel/locking/rtmutex_api.c and move
them there.

Signed-off-b

locking/rtmutex: Split API from implementation

Prepare for reusing the inner functions of rtmutex for RT lock
substitutions: introduce kernel/locking/rtmutex_api.c and move
them there.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Move debug functions as inlines into common header

There is no value in having two header files providing just empty stubs and
a C file which implements trivial debug functions whic

locking/rtmutex: Move debug functions as inlines into common header

There is no value in having two header files providing just empty stubs and
a C file which implements trivial debug functions which can just be inlined.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Decrapify __rt_mutex_init()

The conditional debug handling is just another layer of obfuscation. Split
the function so rt_mutex_init_proxy_locked() can invoke the inner init and
__r

locking/rtmutex: Decrapify __rt_mutex_init()

The conditional debug handling is just another layer of obfuscation. Split
the function so rt_mutex_init_proxy_locked() can invoke the inner init and
__rt_mutex_init() gets the full treatment.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs

None of these functions are used when CONFIG_RT_MUTEXES=n.

Remove the gunk. Remove pointless comments and clean up the coding style
mess

locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs

None of these functions are used when CONFIG_RT_MUTEXES=n.

Remove the gunk. Remove pointless comments and clean up the coding style
mess while at it.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Remove output from deadlock detector

The rtmutex specific deadlock detector predates lockdep coverage of rtmutex
and since commit f5694788ad8da ("rt_mutex: Add lockdep annotations")

locking/rtmutex: Remove output from deadlock detector

The rtmutex specific deadlock detector predates lockdep coverage of rtmutex
and since commit f5694788ad8da ("rt_mutex: Add lockdep annotations") it
contains a lot of redundant functionality:

- lockdep will detect an potential deadlock before rtmutex-debug
has a chance to do so

- the deadlock debugging is restricted to rtmutexes which are not
associated to futexes and have an active waiter, which is covered by
lockdep already

Remove the redundant functionality and move actual deadlock WARN() into the
deadlock code path. The latter needs a seperate cleanup.

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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locking/rtmutex: Remove rtmutex deadlock tester leftovers

The following debug members of 'struct rtmutex' are unused:

- save_state: No users

- file,line: Printed if ::name is NULL. This is only

locking/rtmutex: Remove rtmutex deadlock tester leftovers

The following debug members of 'struct rtmutex' are unused:

- save_state: No users

- file,line: Printed if ::name is NULL. This is only used for non-futex
locks so ::name is never NULL

- magic: Assigned to NULL by rt_mutex_destroy(), no further usage

Remove them along with unused inline and macro leftovers related to
the long gone deadlock tester.

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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kernel/futex: Kill rt_mutex_next_owner()

Update wake_futex_pi() and kill the call altogether. This is possible because:

(i) The case of fixup_owner() in which the pi_mutex was stolen from the
signa

kernel/futex: Kill rt_mutex_next_owner()

Update wake_futex_pi() and kill the call altogether. This is possible because:

(i) The case of fixup_owner() in which the pi_mutex was stolen from the
signaled enqueued top-waiter which fails to trylock and doesn't see a
current owner of the rtmutex but needs to acknowledge an non-enqueued
higher priority waiter, which is the other alternative. This used to be
handled by rt_mutex_next_owner(), which guaranteed fixup_pi_state_owner('newowner')
never to be nil. Nowadays the logic is handled by an EAGAIN loop, without
the need of rt_mutex_next_owner(). Specifically:

c1e2f0eaf015 (futex: Avoid violating the 10th rule of futex)
9f5d1c336a10 (futex: Handle transient "ownerless" rtmutex state correctly)

(ii) rt_mutex_next_owner() and rt_mutex_top_waiter() are semantically
equivalent, as of:

c28d62cf52d7 (locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter())

So instead of keeping the call around, just use the good ole rt_mutex_top_waiter().
No change in semantics.

Signed-off-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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rtmutex: Remove unused argument from rt_mutex_proxy_unlock()

Nothing uses the argument. Remove it as preparation to use
pi_state_update_owner().

Signed-off-by: Thomas Gleixner <[email protected]>

rtmutex: Remove unused argument from rt_mutex_proxy_unlock()

Nothing uses the argument. Remove it as preparation to use
pi_state_update_owner().

Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: [email protected]

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locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()

In -RT task_blocks_on_rt_mutex() may return with -EAGAIN due to
(->pi_blocked_on == PI_WAKEUP_INPROGRESS) before it added i

locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()

In -RT task_blocks_on_rt_mutex() may return with -EAGAIN due to
(->pi_blocked_on == PI_WAKEUP_INPROGRESS) before it added itself as a
waiter. In such a case remove_waiter() must not be called because without a
waiter it will trigger the BUG_ON() statement.

This was initially reported by Yimin Deng. Thomas Gleixner fixed it then
with an explicit check for waiters before calling remove_waiter().

Instead of an explicit NULL check before calling rt_mutex_top_waiter() make
the function return NULL if there are no waiters. With that fixed the now
pointless NULL check is removed from rt_mutex_slowlock().

Reported-and-debugged-by: Yimin Deng <[email protected]>
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/CAAh1qt=DCL9aUXNxanP5BKtiPp3m+qj4yB+gDohhXPVFCxWwzg@mail.gmail.com
Link: https://lkml.kernel.org/r/[email protected]

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futex: Avoid violating the 10th rule of futex

Julia reported futex state corruption in the following scenario:

waiter waker

futex: Avoid violating the 10th rule of futex

Julia reported futex state corruption in the following scenario:

waiter waker stealer (prio > waiter)

futex(WAIT_REQUEUE_PI, uaddr, uaddr2,
timeout=[N ms])
futex_wait_requeue_pi()
futex_wait_queue_me()
freezable_schedule()
<scheduled out>
futex(LOCK_PI, uaddr2)
futex(CMP_REQUEUE_PI, uaddr,
uaddr2, 1, 0)
/* requeues waiter to uaddr2 */
futex(UNLOCK_PI, uaddr2)
wake_futex_pi()
cmp_futex_value_locked(uaddr2, waiter)
wake_up_q()
<woken by waker>
<hrtimer_wakeup() fires,
clears sleeper->task>
futex(LOCK_PI, uaddr2)
__rt_mutex_start_proxy_lock()
try_to_take_rt_mutex() /* steals lock */
rt_mutex_set_owner(lock, stealer)
<preempted>
<scheduled in>
rt_mutex_wait_proxy_lock()
__rt_mutex_slowlock()
try_to_take_rt_mutex() /* fails, lock held by stealer */
if (timeout && !timeout->task)
return -ETIMEDOUT;
fixup_owner()
/* lock wasn't acquired, so,
fixup_pi_state_owner skipped */

return -ETIMEDOUT;

/* At this point, we've returned -ETIMEDOUT to userspace, but the
* futex word shows waiter to be the owner, and the pi_mutex has
* stealer as the owner */

futex_lock(LOCK_PI, uaddr2)
-> bails with EDEADLK, futex word says we're owner.

And suggested that what commit:

73d786bd043e ("futex: Rework inconsistent rt_mutex/futex_q state")

removes from fixup_owner() looks to be just what is needed. And indeed
it is -- I completely missed that requeue_pi could also result in this
case. So we need to restore that, except that subsequent patches, like
commit:

16ffa12d7425 ("futex: Pull rt_mutex_futex_unlock() out from under hb->lock")

changed all the locking rules. Even without that, the sequence:

- if (rt_mutex_futex_trylock(&q->pi_state->pi_mutex)) {
- locked = 1;
- goto out;
- }

- 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);

already suggests there were races; otherwise we'd never have to look
at next_owner.

So instead of doing 3 consecutive wait_lock sections with who knows
what races, we do it all in a single section. Additionally, the usage
of pi_state->owner in fixup_owner() was only safe because only the
rt_mutex owner would modify it, which this additional case wrecks.

Luckily the values can only change away and not to the value we're
testing, this means we can do a speculative test and double check once
we have the wait_lock.

Fixes: 73d786bd043e ("futex: Rework inconsistent rt_mutex/futex_q state")
Reported-by: Julia Cartwright <[email protected]>
Reported-by: Gratian Crisan <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Julia Cartwright <[email protected]>
Tested-by: Gratian Crisan <[email protected]>
Cc: Darren Hart <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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locking/rtmutex: replace top-waiter and pi_waiters leftmost caching

... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.190

locking/rtmutex: replace top-waiter and pi_waiters leftmost caching

... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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futex: Allow for compiling out PI support

This makes it possible to preserve basic futex support and compile out the
PI support when RT mutexes are not available.

Signed-off-by: Nicolas Pitre <nico

futex: Allow for compiling out PI support

This makes it possible to preserve basic futex support and compile out the
PI support when RT mutexes are not available.

Signed-off-by: Nicolas Pitre <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Darren Hart <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]

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rtmutex: Fix PI chain order integrity

rt_mutex_waiter::prio is a copy of task_struct::prio which is updated
during the PI chain walk, such that the PI chain order isn't messed up
by (asynchronous) t

rtmutex: Fix PI chain order integrity

rt_mutex_waiter::prio is a copy of task_struct::prio which is updated
during the PI chain walk, such that the PI chain order isn't messed up
by (asynchronous) task state updates.

Currently rt_mutex_waiter_less() uses task state for deadline tasks;
this is broken, since the task state can, as said above, change
asynchronously, causing the RB tree order to change without actual
tree update -> FAIL.

Fix this by also copying the deadline into the rt_mutex_waiter state
and updating it along with its prio field.

Ideally we would also force PI chain updates whenever DL tasks update
their deadline parameter, but for first approximation this is less
broken than it was.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

show more ...