On 12/2/23 3:46 AM, Jason Gunthorpe wrote:
On Wed, Nov 15, 2023 at 11:02:25AM +0800, Lu Baolu wrote:
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index d19031c1b0e6..c17d5979d70d 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -597,6 +597,8 @@ struct iommu_device {
/**
* struct iommu_fault_param - per-device IOMMU fault data
* @lock: protect pending faults list
+ * @users: user counter to manage the lifetime of the data, this field
+ * is protected by dev->iommu->lock.
* @dev: the device that owns this param
* @queue: IOPF queue
* @queue_list: index into queue->devices
@@ -606,6 +608,7 @@ struct iommu_device {
*/
struct iommu_fault_param {
struct mutex lock;
+ int users;
Use refcount_t for the debugging features
Yes.
struct device *dev;
struct iopf_queue *queue;
But why do we need this to be refcounted? iopf_queue_remove_device()
is always called before we get to release? This struct isn't very big
so I'd just leave it allocated and free it during release?
iopf_queue_remove_device() should always be called before device
release.
The reference counter is implemented to synchronize access to the fault
parameter among different paths. For example, iopf_queue_remove_device()
removes the parameter, while iommu_report_device_fault() and
iommu_page_response() have needs to reference it. These three paths
could possibly happen in different threads.
@@ -72,23 +115,14 @@ static int iommu_handle_iopf(struct iommu_fault *fault, struct device *dev)
struct iopf_group *group;
struct iopf_fault *iopf, *next;
struct iommu_domain *domain = NULL;
- struct iommu_fault_param *iopf_param;
- struct dev_iommu *param = dev->iommu;
+ struct iommu_fault_param *iopf_param = dev->iommu->fault_param;
- lockdep_assert_held(¶m->lock);
+ lockdep_assert_held(&iopf_param->lock);
This patch seems like it is doing a few things, can the locking
changes be kept in their own patch?
Yes. Let me try to.
Best regards,
baolu
