Re: [PATCH 1/1] backing-dev: refactor wb_congested_put()

From: Andrew Morton
Date: Wed Mar 11 2020 - 23:00:27 EST


On Wed, 11 Mar 2020 19:29:48 -0700 Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:

> On Wed, Mar 11, 2020 at 05:59:19PM -0700, Andrew Morton wrote:
> > hm, it's hard to get excited over this. Open-coding the
> > refcount_dec_and_lock_irqsave() internals at a callsite in order to
> > make sparse happy.
> >
> > Is there some other way, using __acquires (for example)?
>
> sparse is really bad at conditional lock acquisition.

I can well imagine.

> we have similar
> problems over the vfs. but we shouldn't be obfuscating our code to make
> the tool happy.

Perhaps sparse needs a way of being directed to suppress checking
across a particular function.