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>

8 files changed, 39 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index de211ac3853e..77201d3f7479 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -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
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index bef47725d4ad..4a81b7fb191a 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -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
diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index ab9a264cb194..f7237c5f531e 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -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
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 6b0f85f02c79..4fad0a34b997 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -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
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index b8ef1787a191..2b649c46631c 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -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
 
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 232c298c933f..c17a194beb0e 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -53,6 +53,11 @@ config RWSEM_XCHGADD_ALGORITHM
         bool
         default y
 
+config GENERIC_LOCKBREAK
+        bool
+        default y
+        depends on SMP && PREEMPT
+
 config ARCH_HAS_ILOG2_U32
         bool
         default y
diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig
index 10b212a1f9f5..1e25bce0366d 100644
--- a/arch/sparc64/Kconfig
+++ b/arch/sparc64/Kconfig
@@ -200,6 +200,11 @@ config US2E_FREQ
           If in doubt, say N.
 
 # Global things across all Sun machines.
+config GENERIC_LOCKBREAK
+        bool
+        default y
+        depends on SMP && PREEMPT
+
 config RWSEM_GENERIC_SPINLOCK
         bool
 
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 23936301db56..db434f8171d3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -19,6 +19,10 @@ config X86_64
 config X86
         def_bool y
 
+config GENERIC_LOCKBREAK
+        def_bool y
+        depends on SMP && PREEMPT
+
 config GENERIC_TIME
         def_bool y