Change DEFINE_SEMAPHORE() to take a number argument

Fundamentally semaphores are a counted primitive, but
DEFINE_SEMAPHORE() does not expose this and explicitly creates a
binary semaphore.

Change D

Change DEFINE_SEMAPHORE() to take a number argument

Fundamentally semaphores are a counted primitive, but
DEFINE_SEMAPHORE() does not expose this and explicitly creates a
binary semaphore.

Change DEFINE_SEMAPHORE() to take a number argument and use that in the
few places that open-coded it using __SEMAPHORE_INITIALIZER().

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
[mcgrof: add some tribal knowledge about why some folks prefer
binary sempahores over mutexes]
Reviewed-by: Sergey Senozhatsky <[email protected]>
Reviewed-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 436

Based on 1 normalized pattern(s):

distributed under the terms of the gnu gpl version 2

extracted by the scancode license scanne

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 436

Based on 1 normalized pattern(s):

distributed under the terms of the gnu gpl version 2

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 2 file(s).

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Armijn Hemel <[email protected]>
Reviewed-by: Allison Randal <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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locking/semaphore: Update the file path in documentation

While reading this header I noticed that the locking stuff has moved to
kernel/locking/*, so update the path in semaphore.h to point to that.

locking/semaphore: Update the file path in documentation

While reading this header I noticed that the locking stuff has moved to
kernel/locking/*, so update the path in semaphore.h to point to that.

Signed-off-by: Tycho Andersen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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locking, semaphores: Annotate inner lock as raw

There is no reason to have the spin_lock protecting the semaphore
preemptible on -rt. Annotate it as a raw_spinlock.

In mainline this change document

locking, semaphores: Annotate inner lock as raw

There is no reason to have the spin_lock protecting the semaphore
preemptible on -rt. Annotate it as a raw_spinlock.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

( On rt this also solves lockdep complaining about the
rt_mutex.wait_lock being not initialized. )

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

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semaphore: Remove mutex emulation

Semaphores used as mutexes have been deprecated for years. Now that
all users are either converted to real semaphores or to mutexes remove
the cruft.

Signed-off-by

semaphore: Remove mutex emulation

Semaphores used as mutexes have been deprecated for years. Now that
all users are either converted to real semaphores or to mutexes remove
the cruft.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Christoph Hellwig <[email protected]>
LKML-Reference: <[email protected]>

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semaphore: Add DEFINE_SEMAPHORE

The full cleanup of init_MUTEX[_LOCKED] and DECLARE_MUTEX has not been
done. Some of the users are real semaphores and we should name them as
such instead of confusin

semaphore: Add DEFINE_SEMAPHORE

The full cleanup of init_MUTEX[_LOCKED] and DECLARE_MUTEX has not been
done. Some of the users are real semaphores and we should name them as
such instead of confusing everyone with "MUTEX".

Provide the infrastructure to get finally rid of init_MUTEX[_LOCKED]
and DECLARE_MUTEX.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Christoph Hellwig <[email protected]>
LKML-Reference: <[email protected]>

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Remove __DECLARE_SEMAPHORE_GENERIC

There are no users of __DECLARE_SEMAPHORE_GENERIC in the kernel

Signed-off-by: Matthew Wilcox <[email protected]>

Improve semaphore documentation

Move documentation from semaphore.h to semaphore.c as requested by
Andrew Morton. Also reformat to kernel-doc style and add some more
notes about the implementation.

Improve semaphore documentation

Move documentation from semaphore.h to semaphore.c as requested by
Andrew Morton. Also reformat to kernel-doc style and add some more
notes about the implementation.

Signed-off-by: Matthew Wilcox <[email protected]>

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Simplify semaphore implementation

By removing the negative values of 'count' and relying on the wait_list to
indicate whether we have any waiters, we can simplify the implementation
by removing the

Simplify semaphore implementation

By removing the negative values of 'count' and relying on the wait_list to
indicate whether we have any waiters, we can simplify the implementation
by removing the protection against an unlikely race condition. Thanks to
David Howells for his suggestions.

Signed-off-by: Matthew Wilcox <[email protected]>

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Add down_timeout and change ACPI to use it

ACPI currently emulates a timeout for semaphores with calls to
down_trylock and sleep. This produces horrible behaviour in terms of
fairness and excessive

Add down_timeout and change ACPI to use it

ACPI currently emulates a timeout for semaphores with calls to
down_trylock and sleep. This produces horrible behaviour in terms of
fairness and excessive wakeups. Now that we have a unified semaphore
implementation, adding a real down_trylock is almost trivial.

Signed-off-by: Matthew Wilcox <[email protected]>

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Introduce down_killable()

down_killable() is the functional counterpart of mutex_lock_killable.

Signed-off-by: Matthew Wilcox <[email protected]>

Generic semaphore implementation

Semaphores are no longer performance-critical, so a generic C
implementation is better for maintainability, debuggability and
extensibility. Thanks to Peter Zijlstr

Generic semaphore implementation

Semaphores are no longer performance-critical, so a generic C
implementation is better for maintainability, debuggability and
extensibility. Thanks to Peter Zijlstra for fixing the lockdep
warning. Thanks to Harvey Harrison for pointing out that the
unlikely() was unnecessary.

Signed-off-by: Matthew Wilcox <[email protected]>
Acked-by: Ingo Molnar <[email protected]>

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