linux-kernel - Re: [PATCH 7/7] kgdb: Remove irq flags and local_irq

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Date:   Tue, 30 Oct 2018 15:22:40 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Jason Wessel <jason.wessel@...driver.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        kgdb-bugreport@...ts.sourceforge.net, kstewart@...uxfoundation.org,
        linux-mips@...ux-mips.org, dalias@...c.org,
        linux-sh@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Will Deacon <will.deacon@....com>,
        LKML <linux-kernel@...r.kernel.org>, mhocko@...e.com,
        paulus@...ba.org, "H. Peter Anvin" <hpa@...or.com>,
        sparclinux@...r.kernel.org, linux-hexagon@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        ysato@...rs.sourceforge.jp, mpe@...erman.id.au, x86@...nel.org,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Ingo Molnar <mingo@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>, jhogan@...nel.org,
        linux-snps-arc@...ts.infradead.org, ying.huang@...el.com,
        rppt@...ux.vnet.ibm.com, bp@...en8.de,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        christophe.leroy@....fr, pombredanne@...b.com,
        Ralf Baechle <ralf@...ux-mips.org>, rkuo@...eaurora.org,
        paul.burton@...s.com, Vineet Gupta <vgupta@...opsys.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH 7/7] kgdb: Remove irq flags and local_irq_enable/disable
 from roundup

Hi,

On Tue, Oct 30, 2018 at 4:46 AM Daniel Thompson
<daniel.thompson@...aro.org> wrote:
>
> On Mon, Oct 29, 2018 at 11:07:07AM -0700, Douglas Anderson wrote:
> > The function kgdb_roundup_cpus() was passed a parameter that was
> > documented as:
> >
> > > the flags that will be used when restoring the interrupts. There is
> > > local_irq_save() call before kgdb_roundup_cpus().
> >
> > Nobody used those flags.  Anyone who wanted to temporarily turn on
> > interrupts just did local_irq_enable() and local_irq_disable() without
> > looking at them.  So we can definitely remove the flags.
>
> On the whole I'd rather that this change...
>
>
> > Speaking of calling local_irq_enable(), it seems like a bad idea and
> > it caused a nice splat on my system with lockdep turned on.
> > Specifically it hit:
> >   DEBUG_LOCKS_WARN_ON(current->hardirq_context)
>
> ... and fixes for this this were in separate patches. They don't appear
> especially related.

Agreed that this is cleaner.  Done for v2.

-Doug