From 3609d819a36c65857816ca1278d80767d6d9b990 Mon Sep 17 00:00:00 2001
From: "Shreyas B. Prabhu" <shreyas@linux.vnet.ibm.com>
Date: Wed, 20 May 2015 00:30:14 +0530
Subject: [PATCH] powerpc: Make doorbell check preemption safe

Doorbell can be used to cause ipi on cpus which are sibling threads on
the same core. So icp_native_cause_ipi checks if the destination cpu
is a sibling thread of the current cpu and uses doorbell in such cases.

But while running with CONFIG_PREEMPT=y, since this section is
preemtible, we can run into issues if after we check if the destination
cpu is a sibling cpu, the task gets migrated from a sibling cpu to a
cpu on another core.

Fix this by using get_cpu()/ put_cpu()

Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
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