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Commit 95c354fe authored Jan 30, 2008 by Nick Piggin Committed by Ingo Molnar Jan 30, 2008

spinlock: lockbreak cleanup



The break_lock data structure and code for spinlocks is quite nasty.
Not only does it double the size of a spinlock but it changes locking to
a potentially less optimal trylock.

Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a
__raw_spin_is_contended that uses the lock data itself to determine whether
there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is
not set.

Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to
decouple it from the spinlock implementation, and make it typesafe (rwlocks
do not have any need_lockbreak sites -- why do they even get bloated up
with that break_lock then?).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent a95d67f8

arch/arm/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -91,6 +91,11 @@ config GENERIC_IRQ_PROBE
		bool
		default y

		config GENERIC_LOCKBREAK
		bool
		default y
		depends on SMP && PREEMPT

		config RWSEM_GENERIC_SPINLOCK
		bool
		default y

arch/ia64/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -42,6 +42,11 @@ config MMU
		config SWIOTLB
		bool

		config GENERIC_LOCKBREAK
		bool
		default y
		depends on SMP && PREEMPT

		config RWSEM_XCHGADD_ALGORITHM
		bool
		default y

arch/m32r/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -235,6 +235,11 @@ config IRAM_SIZE
		# Define implied options from the CPU selection here
		#

		config GENERIC_LOCKBREAK
		bool
		default y
		depends on SMP && PREEMPT

		config RWSEM_GENERIC_SPINLOCK
		bool
		depends on M32R

arch/mips/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -694,6 +694,11 @@ source "arch/mips/vr41xx/Kconfig"

		endmenu

		config GENERIC_LOCKBREAK
		bool
		default y
		depends on SMP && PREEMPT

		config RWSEM_GENERIC_SPINLOCK
		bool
		default y

arch/parisc/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -19,6 +19,11 @@ config MMU
		config STACK_GROWSUP
		def_bool y

		config GENERIC_LOCKBREAK
		bool
		default y
		depends on SMP && PREEMPT

		config RWSEM_GENERIC_SPINLOCK
		def_bool y