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Commit f05810c9 authored by Suresh Siddha's avatar Suresh Siddha Committed by David Woodhouse
Browse files

dmar: use spin_lock_irqsave() in qi_submit_sync() 



Next patch in the series will use queued invalidation interface
qi_submit_sync() for DMA-remapping aswell, which can be called from interrupt
context.

So use spin_lock_irqsave() instead of spin_lock() in qi_submit_sync().

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarYouquan Song <youquan.song@intel.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 2e532d68

drivers/pci/dmar.c

+13 −6
Original line number Diff line number Diff line
@@ -580,11 +580,11 @@ void qi_submit_sync(struct qi_desc *desc, struct intel_iommu *iommu) 


	hw = qi->desc;



	spin_lock(&qi->q_lock);

	spin_lock_irqsave(&qi->q_lock, flags);

	while (qi->free_cnt < 3) {

		spin_unlock(&qi->q_lock);

		spin_unlock_irqrestore(&qi->q_lock, flags);

		cpu_relax();

		spin_lock(&qi->q_lock);

		spin_lock_irqsave(&qi->q_lock, flags);

	}



	index = qi->free_head;
@@ -605,15 +605,22 @@ void qi_submit_sync(struct qi_desc *desc, struct intel_iommu *iommu) 
	qi->free_head = (qi->free_head + 2) % QI_LENGTH;

	qi->free_cnt -= 2;



	spin_lock_irqsave(&iommu->register_lock, flags);

	spin_lock(&iommu->register_lock);

	/*

	 * update the HW tail register indicating the presence of

	 * new descriptors.

	 */

	writel(qi->free_head << 4, iommu->reg + DMAR_IQT_REG);

	spin_unlock_irqrestore(&iommu->register_lock, flags);

	spin_unlock(&iommu->register_lock);



	while (qi->desc_status[wait_index] != QI_DONE) {

		/*

		 * We will leave the interrupts disabled, to prevent interrupt

		 * context to queue another cmd while a cmd is already submitted

		 * and waiting for completion on this cpu. This is to avoid

		 * a deadlock where the interrupt context can wait indefinitely

		 * for free slots in the queue.

		 */

		spin_unlock(&qi->q_lock);

		cpu_relax();

		spin_lock(&qi->q_lock);
@@ -622,7 +629,7 @@ void qi_submit_sync(struct qi_desc *desc, struct intel_iommu *iommu) 
	qi->desc_status[index] = QI_DONE;



	reclaim_free_desc(qi);

	spin_unlock(&qi->q_lock);

	spin_unlock_irqrestore(&qi->q_lock, flags);

}



/*