From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 21 Sep 2017 17:21:40 +0200
Subject: iommu/iova: Use raw_cpu_ptr() instead of get_cpu_ptr() for ->fq
Git-commit: 94e2cc4dba39efbb63e84cd4f7243627c16ceac5
Patch-mainline: v4.15-rc1
References: bsc#1096790 bsc#1097034

get_cpu_ptr() disabled preemption and returns the ->fq object of the
current CPU. raw_cpu_ptr() does the same except that it not disable
preemption which means the scheduler can move it to another CPU after it
obtained the per-CPU object.
In this case this is not bad because the data structure itself is
protected with a spin_lock. This change shouldn't matter however on RT
it does because the sleeping lock can't be accessed with disabled
preemption.

Cc: Joerg Roedel <joro@8bytes.org>
Cc: iommu@lists.linux-foundation.org
Reported-by: vinadhy@gmail.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 drivers/iommu/iova.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -561,7 +561,7 @@ void queue_iova(struct iova_domain *iova
 		unsigned long pfn, unsigned long pages,
 		unsigned long data)
 {
-	struct iova_fq *fq = get_cpu_ptr(iovad->fq);
+	struct iova_fq *fq = raw_cpu_ptr(iovad->fq);
 	unsigned long flags;
 	unsigned idx;
 
@@ -593,8 +593,6 @@ void queue_iova(struct iova_domain *iova
 	    !atomic_cmpxchg(&iovad->fq_timer_on, 0, 1))
 		mod_timer(&iovad->fq_timer,
 			  jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
-
-	put_cpu_ptr(iovad->fq);
 }
 EXPORT_SYMBOL_GPL(queue_iova);