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Date: Fri, 6 Apr 2018 18:34:50 +0100
From: Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 1/5] arm64: entry: isb in el1_irq
Message-ID: <20180406173450.5h7lgh2xdtcs5fbs@lakrids.cambridge.arm.com>
References: <20180405171800.5648-1-ynorov@caviumnetworks.com>
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To: James Morse <james.morse@arm.com>
Cc: Yury Norov <ynorov@caviumnetworks.com>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Will Deacon <will.deacon@arm.com>, Chris Metcalf <cmetcalf@mellanox.com>, Christopher Lameter <cl@linux.com>, Russell King - ARM Linux <linux@armlinux.org.uk>, Steven Rostedt <rostedt@goodmis.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Catalin Marinas <catalin.marinas@arm.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Alexey Klimov <klimov.linux@gmail.com>, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org

On Fri, Apr 06, 2018 at 06:30:50PM +0100, James Morse wrote:
> Hi Mark,
> 
> On 06/04/18 18:22, Mark Rutland wrote:
> > Digging a bit, I also thing that our ct_user_exit and ct_user_enter
> > usage is on dodgy ground today.
> 
> [...]
> 
> > I think similar applies to SDEI; we don't negotiate with RCU prior to
> > invoking handlers, which might need RCU.
> 
> The arch code's __sdei_handler() calls nmi_enter() -> rcu_nmi_enter(), which
> does a rcu_dynticks_eqs_exit().

Ah, sorry. I missed that!

Thanks,
Mark.