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iommu/iova: Use raw_cpu_ptr() instead of get_cpu_ptr() for ->fq 

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>
hifive-unleashed-5.1
Sebastian Andrzej Siewior 2017-09-21 17:21:40 +02:00 committed by Alex Williamson
parent a593472591
commit 94e2cc4dba
1 changed files with 1 additions and 3 deletions
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4
drivers/iommu/iova.c
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@ -542,7 +542,7 @@ void queue_iova(struct iova_domain *iovad,
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;
@ -572,8 +572,6 @@ void queue_iova(struct iova_domain *iovad,
if (atomic_cmpxchg(&iovad->fq_timer_on, 0, 1) == 0)
mod_timer(&iovad->fq_timer,
jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
put_cpu_ptr(iovad->fq);
}
EXPORT_SYMBOL_GPL(queue_iova);