diff options
| -rw-r--r-- | drivers/pci/dmar.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c index e842e756308..b64cec19054 100644 --- a/drivers/pci/dmar.c +++ b/drivers/pci/dmar.c @@ -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); } /* |