Re: [PATCH 1/2] wait: kill is_sync_wait()

[Ingo Molnar <mingo@elte.hu>]

* Tejun Heo <tj@kernel.org> wrote:

> is_sync_wait() is used to distinguish between sync and async waits.
> Basically sync waits are the ones initialized with
> init_waitqueue_entry() and async ones with init_waitqueue_func_entry().
> The sync/async distinction is used only in prepare_to_wait[_exclusive]()
> and its only function is to skip setting the current task state if the
> wait is async.  This has a few problems.
> 
> * No one uses it.  None of func_entry users use prepare_to_wait()
>   functions, so the code path never gets executed.
> 
> * The distinction is bogus.  Maybe back when func_entry is used only
>   by aio but it's now also used by epoll and in future possibly by 9p
>   and poll/select.
> 
> * Taking @state as argument and ignoring it silenly depending on how
>   @wait is initialized is just a bad error-prone API.
> 
> * It prevents func_entry waits from using wait->private for no good
>   reason.
> 
> This patch kills is_sync_wait() and the associated code paths from
> prepare_to_wait[_exclusive]().  As there was no user of these code
> paths, this patch doesn't cause any behavior difference.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>

good spotting.

Acked-by: Ingo Molnar <mingo@elte.hu>

	Ingo