uacce: Handle parent device removal or parent driver module rmmod

[ Upstream commit 80fc671bcc0173836e9032b0c698ea74c13b9d7c ]

The uacce driver must deal with a possible removal of the parent device
or parent driver module rmmod at any time.

Although uacce_remove(), called on device removal and on driver unbind,
prevents future use of the uacce fops by removing the cdev, fops that
were called before that point may still be running.

Serialize uacce_fops_open() and uacce_remove() with uacce->mutex.
Serialize other fops against uacce_remove() with q->mutex.
Since we need to protect uacce_fops_poll() which gets called on the fast
path, replace uacce->queues_lock with q->mutex to improve scalability.
The other fops are only used during setup.

uacce_queue_is_valid(), checked under q->mutex or uacce->mutex, denotes
whether uacce_remove() has disabled all queues. If that is the case,
don't go any further since the parent device is being removed and
uacce->ops should not be called anymore.

Reported-by: Yang Shen <shenyang39@huawei.com>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20220701034843.7502-1-zhangfei.gao@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/uacce.h b/include/linux/uacce.h
index 48e319f40275..9ce88c28b0a8 100644
--- a/include/linux/uacce.h
+++ b/include/linux/uacce.h
@@ -70,6 +70,7 @@ enum uacce_q_state {
  * @wait: wait queue head
  * @list: index into uacce queues list
  * @qfrs: pointer of qfr regions
+ * @mutex: protects queue state
  * @state: queue state machine
  * @pasid: pasid associated to the mm
  * @handle: iommu_sva handle returned by iommu_sva_bind_device()
@@ -80,6 +81,7 @@ struct uacce_queue {
 	wait_queue_head_t wait;
 	struct list_head list;
 	struct uacce_qfile_region *qfrs[UACCE_MAX_REGION];
+	struct mutex mutex;
 	enum uacce_q_state state;
 	u32 pasid;
 	struct iommu_sva *handle;
@@ -97,9 +99,9 @@ struct uacce_queue {
  * @dev_id: id of the uacce device
  * @cdev: cdev of the uacce
  * @dev: dev of the uacce
+ * @mutex: protects uacce operation
  * @priv: private pointer of the uacce
  * @queues: list of queues
- * @queues_lock: lock for queues list
  * @inode: core vfs
  */
 struct uacce_device {
@@ -113,9 +115,9 @@ struct uacce_device {
 	u32 dev_id;
 	struct cdev *cdev;
 	struct device dev;
+	struct mutex mutex;
 	void *priv;
 	struct list_head queues;
-	struct mutex queues_lock;
 	struct inode *inode;
 };