[PATCH 2/2] arm64: factor work_pending state machine to C

Catalin Marinas
2016-01-06T12:30:11Z

On Tue, Jan 05, 2016 at 05:33:35PM +0000, Mark Rutland wrote:
> Currently ret_fast_syscall, work_pending, and ret_to_user form an ad-hoc
> state machine that can be difficult to reason about due to duplicated
> code and a large number of branch targets.
>
> This patch factors the common logic out into the existing
> do_notify_resume function, converting the code to C in the process,
> making the code more legible.
>
> This patch tries to mirror the existing behaviour as closely as possible
> while using the usual C control flow primitives. There should be no
> functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Chris Metcalf <cmetcalf@ezchip.com>
> Cc: Will Deacon <will.deacon@arm.com>

This is definitely cleaner. The only downside is slightly more expensive
ret_fast_syscall. I guess it's not noticeable (though we could do some
quick benchmark like getpid in a loop). Anyway, I'm fine with the patch:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>