Re: [PATCH] Introduce down_try() so we can move away from down_trylock()

[Paul Menage]

On Mon, Jul 28, 2008 at 5:15 PM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
> I planned on removing the much-disliked down_trylock() (with its
> backwards return codes) in 2.6.27, but it's creating something of a
> logjam with other patches in -mm and linux-next.
>
> Andrew suggested introducing "down_try" as a wrapper now, to make
> the transition easier.  Linus, please apply.
>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Cc: Matthew Wilcox <matthew@xxxxxx>
> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> ---
>  include/linux/semaphore.h |   14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff -r 92664ae4130b include/linux/semaphore.h
> --- a/include/linux/semaphore.h Wed May 21 14:54:40 2008 +1000
> +++ b/include/linux/semaphore.h Wed May 21 15:07:31 2008 +1000
> @@ -48,4 +48,18 @@ extern int __must_check down_timeout(str
>  extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
>  extern void up(struct semaphore *sem);
>
> +/**
> + * down_try - try to down a semaphore, but don't block
> + * @sem: the semaphore
> + *
> + * This is equivalent to down_trylock(), but has the same return codes as
> + * spin_trylock and mutex_trylock: 1 if semaphore acquired, 0 if not.

Is there a reason to avoid using a return type of "bool" for this?

Paul
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