Re: CVS commit: src/sys/kern

[Andrew Doran <ad%netbsd.org@localhost>]

Hi Manuel,

On Tue, May 05, 2009 at 08:26:37PM +0000, Manuel Bouyer wrote:

> Module Name:  src
> Committed By: bouyer
> Date:         Tue May  5 20:26:36 UTC 2009
> 
> Modified Files:
>       src/sys/kern: kern_softint.c
> 
> Log Message:
> Declare sh_flags volatile.
> Without it, on ports where splhigh() is inline, the compiler will optimise
> the second SOFTINT_PENDING test in softint_schedule(). A dissasembly
> of softint_schedule() with and without the volatile sh_flags confirm this
> on sparc.
> Because of this there is a race that could lead to the softhand_t
> being enqueued twice on si_q, leading to a corrupted queue and
> some handler being SOFTINT_PENDING but never called.
> 
> Should fix PR kern/38637

Your change works around a bug with sparc64 or perhaps even gcc. Please
address the root cause instead. Thanks.