Re: [patch] spinlocks: remove 'volatile'

[Heiko Carstens]

> Subject: spinlocks: remove 'volatile'
> From: Ingo Molnar <mingo@xxxxxxx>
> 
> remove 'volatile' from the spinlock types, it causes gcc to
> generate really bad code. (and it's pointless anyway)
> 
> this reduces the non-debug SMP kernel's size by 0.2% (!).
> 
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> ---
>  include/asm-i386/spinlock_types.h   |    4 ++--
>  include/asm-x86_64/spinlock_types.h |    4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> Index: linux/include/asm-i386/spinlock_types.h
> ===================================================================
> --- linux.orig/include/asm-i386/spinlock_types.h
> +++ linux/include/asm-i386/spinlock_types.h
> @@ -6,13 +6,13 @@
>  #endif
>  
>  typedef struct {
> -	volatile unsigned int slock;
> +	unsigned int slock;
>  } raw_spinlock_t;
>  
>  #define __RAW_SPIN_LOCK_UNLOCKED	{ 1 }
>  
>  typedef struct {
> -	volatile unsigned int lock;
> +	unsigned int lock;
>  } raw_rwlock_t;

Shouldn't the __raw_read_can_lock and __raw_write_can_lock macros be changed too, just
to make sure the value gets read every single time if it's used in a loop?
Just like the __raw_spin_is_locked already has a (volatile signed char * cast)?
-
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