[PATCH v2 13/17] drm/panthor: Track user owned VMs

[Boris Brezillon <boris.brezillon@collabora.com>]

We will soon need this to fix the unplug logic and make sure panthor_vm
objects are not left behind after an unplug.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 93e9d55da783..5672d437d52d 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -107,12 +107,15 @@ struct panthor_mmu {
 
 	/** @vm: VMs management fields */
 	struct {
-		/** @vm.lock: Lock protecting access to list. */
+		/** @vm.lock: Lock protecting access to list and user_owned. */
 		struct mutex lock;
 
 		/** @vm.list: List containing all VMs. */
 		struct list_head list;
 
+		/** @vm.list: List containing VMs with a valid handle. */
+		struct list_head user_owned;
+
 		/** @vm.reset_in_progress: True if a reset is in progress. */
 		bool reset_in_progress;
 
@@ -427,6 +430,9 @@ struct panthor_vm {
 	/** @node: Used to insert the VM in the panthor_mmu::vm::list. */
 	struct list_head node;
 
+	/* @user_node: Used to insert the VM in the panthor_mmu::vm::user_owned list. */
+	struct list_head user_node;
+
 	/** @for_mcu: True if this is the MCU VM. */
 	bool for_mcu;
 
@@ -1669,10 +1675,19 @@ int panthor_vm_pool_create_vm(struct panthor_device *ptdev,
 	drm_gem_object_get(&pool->dummy->base);
 	vm->dummy = pool->dummy;
 
+	/* Insert in the list before xa_alloc() so we can't race with
+	 * panthor_vm_pool_destroy_vm() have the VM inserted in the
+	 * user_owned list after it's been destroyed.
+	 */
+	scoped_guard(mutex, &ptdev->mmu->vm.lock)
+		list_add_tail(&vm->user_node, &ptdev->mmu->vm.user_owned);
+
 	ret = xa_alloc(&pool->xa, &id, vm,
 		       XA_LIMIT(1, PANTHOR_MAX_VMS_PER_FILE), GFP_KERNEL);
 
 	if (ret) {
+		scoped_guard(mutex, &ptdev->mmu->vm.lock)
+			list_del_init(&vm->user_node);
 		panthor_vm_put(vm);
 		return ret;
 	}
@@ -1727,13 +1742,19 @@ static void panthor_vm_destroy(struct panthor_vm *vm)
  */
 int panthor_vm_pool_destroy_vm(struct panthor_vm_pool *pool, u32 handle)
 {
+	struct panthor_device *ptdev;
 	struct panthor_vm *vm;
 
 	vm = xa_erase(&pool->xa, handle);
+	if (!vm)
+		return -EINVAL;
+
+	ptdev = container_of(vm->as->base.drm, struct panthor_device, base);
+	scoped_guard(mutex, &ptdev->mmu->vm.lock)
+		list_del_init(&vm->user_node);
 
 	panthor_vm_destroy(vm);
-
-	return vm ? 0 : -EINVAL;
+	return 0;
 }
 
 /**
@@ -3118,6 +3139,7 @@ panthor_vm_create(struct panthor_device *ptdev, bool for_mcu,
 		goto err_put_as;
 	}
 
+	INIT_LIST_HEAD(&vm->user_node);
 	vm->user_va_range = kernel_va_start;
 	vm->as = as;
 	mutex_init(&vm->heaps.lock);
@@ -3626,6 +3648,7 @@ int panthor_mmu_init(struct panthor_device *ptdev)
 		return ret;
 
 	INIT_LIST_HEAD(&mmu->vm.list);
+	INIT_LIST_HEAD(&mmu->vm.user_owned);
 	ret = drmm_mutex_init(&ptdev->base, &mmu->vm.lock);
 	if (ret)
 		return ret;

-- 
2.55.0