Re: [PATCH] local_t protection (critical section)

Christoph Lameter
2007-09-12T22:33:21Z

On Wed, 5 Sep 2007, Mathieu Desnoyers wrote:

> Index: linux-2.6-lttng/include/asm-generic/local.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/asm-generic/local.h 2007-09-04 15:32:02.000000000 -0400
> +++ linux-2.6-lttng/include/asm-generic/local.h 2007-09-05 08:50:47.000000000 -0400
> @@ -46,6 +46,15 @@ typedef struct
> #define local_add_unless(l, a, u) atomic_long_add_unless((&(l)->a), (a), (u))
> #define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
>
> +#define local_enter_save(flags) local_irq_save(flags)
> +#define local_exit_restore(flags) local_irq_restore(flags)
> +#define local_enter() local_irq_disable()
> +#define local_exit() local_irq_enable()
> +#define local_nest_irq_save(flags) (flags)
> +#define local_nest_irq_restore(flags) (flags)
> +#define local_nest_irq_disable()
> +#define local_nest_irq_enable()
> +

This list is going to increase with RT support in SLUB? Argh.

> Index: linux-2.6-lttng/include/asm-i386/local.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/asm-i386/local.h 2007-09-04 15:28:52.000000000 -0400
> +++ linux-2.6-lttng/include/asm-i386/local.h 2007-09-05 08:49:19.000000000 -0400
> @@ -194,6 +194,23 @@ static __inline__ long local_sub_return(
> })
> #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
>
> +#define local_enter_save(flags) \
> + do { \
> + (flags); \
> + preempt_disable(); \
> + } while (0)

> +#define local_exit_restore(flags) \
> + do { \
> + (flags); \
> + preempt_enable(); \
> + } while (0)

This does not result in warnings because a variable is not used or used
uninitialized?