| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Tue, 5 Sep 2017 14:11:41 +0200 |
| Subject: iommu/amd: Use raw_cpu_ptr() instead of get_cpu_ptr() for |
| ->flush_queue |
| |
| get_cpu_ptr() disabled preemption and returns the ->flush_queue 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: rt-stable@vger.kernel.org |
| Cc: Joerg Roedel <joro@8bytes.org> |
| Cc: iommu@lists.linux-foundation.org |
| Reported-by: Vinod Adhikary <vinadhy@gmail.com> |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| drivers/iommu/amd_iommu.c | 4 +--- |
| 1 file changed, 1 insertion(+), 3 deletions(-) |
| |
| --- a/drivers/iommu/amd_iommu.c |
| +++ b/drivers/iommu/amd_iommu.c |
| @@ -2289,7 +2289,7 @@ static void queue_add(struct dma_ops_dom |
| pages = __roundup_pow_of_two(pages); |
| address >>= PAGE_SHIFT; |
| |
| - queue = get_cpu_ptr(&flush_queue); |
| + queue = raw_cpu_ptr(&flush_queue); |
| spin_lock_irqsave(&queue->lock, flags); |
| |
| if (queue->next == FLUSH_QUEUE_SIZE) |
| @@ -2306,8 +2306,6 @@ static void queue_add(struct dma_ops_dom |
| |
| if (atomic_cmpxchg(&queue_timer_on, 0, 1) == 0) |
| mod_timer(&queue_timer, jiffies + msecs_to_jiffies(10)); |
| - |
| - put_cpu_ptr(&flush_queue); |
| } |
| |
| |
