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>

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 84bda3a..466aaa8 100644 (file)
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -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);