On Wed, Nov 06, 2013 at 10:31:31AM +0100, Peter Zijlstra wrote:
> Subject: mm: Properly separate the bloated ptl from the regular case
>
> Use kernel/bounds.c to convert build-time spinlock_t size into a
> preprocessor symbol and apply that to properly separate the page::ptl
> situation.
>
> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> ---
> include/linux/mm.h | 24 +++++++++++++-----------
> include/linux/mm_types.h | 9 +++++----
> kernel/bounds.c | 2 ++
> mm/memory.c | 11 +++++------
> 4 files changed, 25 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/bounds.c b/kernel/bounds.c
> index e8ca97b5c386..5982437eca2c 100644
> --- a/kernel/bounds.c
> +++ b/kernel/bounds.c
> @@ -11,6 +11,7 @@
> #include <linux/kbuild.h>
> #include <linux/page_cgroup.h>
> #include <linux/log2.h>
> +#include <linux/spinlock.h>
>
> void foo(void)
> {
> @@ -21,5 +22,6 @@ void foo(void)
> #ifdef CONFIG_SMP
> DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS));
> #endif
> + DEFINE(BLOATED_SPINLOCKS, sizeof(spinlock_t) > sizeof(int));
> /* End of constants */
> }
Using that we could also do.. not been near a compiler.
---
Subject: lockref: Use bloated_spinlocks to avoid explicit config dependencies
Avoid the fragile Kconfig construct guestimating spinlock_t sizes; use a
friendly compile-time test to determine this.
Not-Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
lib/Kconfig | 3 ---
lib/lockref.c | 2 +-
2 files changed, 1 insertion(+), 4 deletions(-)
diff --git a/lib/Kconfig b/lib/Kconfig
index b3c8be0da17f..254af289d1d0 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -54,9 +54,6 @@ config ARCH_USE_CMPXCHG_LOCKREF
config CMPXCHG_LOCKREF
def_bool y if ARCH_USE_CMPXCHG_LOCKREF
depends on SMP
- depends on !GENERIC_LOCKBREAK
- depends on !DEBUG_SPINLOCK
- depends on !DEBUG_LOCK_ALLOC
config CRC_CCITT
tristate "CRC-CCITT functions"
diff --git a/lib/lockref.c b/lib/lockref.c
index 6f9d434c1521..a158fd86aa1a 100644
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -1,7 +1,7 @@
#include <linux/export.h>
#include <linux/lockref.h>
-#ifdef CONFIG_CMPXCHG_LOCKREF
+#if defined(CONFIG_CMPXCHG_LOCKREF) && !BLOATED_SPINLOCKS
/*
* Allow weakly-ordered memory architectures to provide barrier-less
--
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