linux-kernel - Re: [PATCH linux-next] powerpc: disable sanitizer in irq_soft_mask

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Date:   Wed, 24 Aug 2022 09:25:45 +0800
From:   Zhouyi Zhou <zhouzhouyi@...il.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        atrajeev@...ux.vnet.ibm.com,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-kernel <linux-kernel@...r.kernel.org>, lance@...osl.org,
        "Paul E. McKenney" <paulmck@...nel.org>, rcu <rcu@...r.kernel.org>
Subject: Re: [PATCH linux-next] powerpc: disable sanitizer in irq_soft_mask_set

On Wed, Aug 24, 2022 at 12:50 AM Christophe Leroy
<christophe.leroy@...roup.eu> wrote:
>
>
>
> Le 23/08/2022 à 10:47, Christophe Leroy a écrit :
> >
> >
> > Le 23/08/2022 à 10:33, Michael Ellerman a écrit :
> >> Zhouyi Zhou <zhouzhouyi@...il.com> writes:
> >>
> >> My worry is that this will force irq_soft_mask_set() out of line, which
> >> we would rather avoid. It's meant to be a fast path.
> >>
> >> In fact with this applied I see nearly 300 out-of-line copies of the
> >> function when building a defconfig, and ~1700 calls to it.
> >>
> >> Normally it is inlined at every call site.
> >>
> >>
> >> So I think I'm inclined to revert ef5b570d3700 ("powerpc/irq: Don't open
> >> code irq_soft_mask helpers").
> >
> > Could you revert it only partially ? In extenso, revert the
> > READ/WRITE_ONCE and bring back the inline asm in irq_soft_mask_return()
> >   and irq_soft_mask_set(), but keep other changes.
>
> I sent a patch doing that.
Thank Christophe for the fix. I am very glad to be of benefit to the
community ;-)
Also thank Michael and Paul for your constant encouragement and
guidance, I learned to use objdump to count the number of failed
inline function calls today ;-)

By the way, from my experiments, both gcc-11 and clang-14 behave the
same as Michael has described.

Cheers
Zhouyi
>
> Christophe