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Message-ID: <e304952f5177f85faff4560ded5aa1dad7af5fe2.camel@linux.ibm.com>
Subject: Re: [PATCH v3 1/1] ppc/crash: Reset spinlocks during crash
From:   Leonardo Bras <leonardo@linux.ibm.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Enrico Weigelt <info@metux.net>,
        Alexios Zavras <alexios.zavras@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Date:   Wed, 01 Apr 2020 20:53:31 -0300
In-Reply-To: <20200401092618.GW20713@hirez.programming.kicks-ass.net>
References: <20200401000020.590447-1-leonardo@linux.ibm.com>
         <20200401092618.GW20713@hirez.programming.kicks-ass.net>
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Hello Peter,=20

On Wed, 2020-04-01 at 11:26 +0200, Peter Zijlstra wrote:
> You might want to add a note to your asm/spinlock.h that you rely on
> spin_unlock() unconditionally clearing a lock.
>=20
> This isn't naturally true for all lock implementations. Consider ticket
> locks, doing a surplus unlock will wreck your lock state in that case.
> So anybody poking at the powerpc spinlock implementation had better know
> you rely on this.

Good idea. I will add this to my changes and generate a v4.

Thank you,

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