[PATCH 11/14] accel/ivpu: Fix locking order in ivpu_job_submit

[Maciej Falkowski]

From: Karol Wachowski <karol.wachowski at intel.com>

Fix deadlock in job submission and abort handling.
When a thread aborts currently executing jobs due to a fault,
it first locks the global lock protecting submitted_jobs (#1).

After the last job is destroyed, it proceeds to release the related context
and locks file_priv (#2). Meanwhile, in the job submission thread,
the file_priv lock (#2) is taken first, and then the submitted_jobs
lock (#1) is obtained when a job is added to the submitted jobs list.

       CPU0                            CPU1
       ----                    	       ----
  (for example due to a fault)         (jobs submissions keep coming)

  lock(&vdev->submitted_jobs_lock) #1
  ivpu_jobs_abort_all()
  job_destroy()
                                      lock(&file_priv->lock)           #2
                                      lock(&vdev->submitted_jobs_lock) #1
  file_priv_release()
  lock(&vdev->context_list_lock)
  lock(&file_priv->lock)           #2

This order of locking causes a deadlock. To resolve this issue,
change the order of locking in ivpu_job_submit().

Signed-off-by: Karol Wachowski <karol.wachowski at intel.com>
Signed-off-by: Maciej Falkowski <maciej.falkowski at linux.intel.com>
---
 drivers/accel/ivpu/ivpu_job.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/accel/ivpu/ivpu_job.c b/drivers/accel/ivpu/ivpu_job.c
index c694822a14bf..c93ea37062d7 100644
--- a/drivers/accel/ivpu/ivpu_job.c
+++ b/drivers/accel/ivpu/ivpu_job.c
@@ -597,6 +597,7 @@ static int ivpu_job_submit(struct ivpu_job *job, u8 priority, u32 cmdq_id)
 	if (ret < 0)
 		return ret;
 
+	mutex_lock(&vdev->submitted_jobs_lock);
 	mutex_lock(&file_priv->lock);
 
 	if (cmdq_id == 0)
@@ -606,19 +607,17 @@ static int ivpu_job_submit(struct ivpu_job *job, u8 priority, u32 cmdq_id)
 	if (!cmdq) {
 		ivpu_warn_ratelimited(vdev, "Failed to get job queue, ctx %d\n", file_priv->ctx.id);
 		ret = -EINVAL;
-		goto err_unlock_file_priv;
+		goto err_unlock;
 	}
 
 	ret = ivpu_cmdq_register(file_priv, cmdq);
 	if (ret) {
 		ivpu_err(vdev, "Failed to register command queue: %d\n", ret);
-		goto err_unlock_file_priv;
+		goto err_unlock;
 	}
 
 	job->cmdq_id = cmdq->id;
 
-	mutex_lock(&vdev->submitted_jobs_lock);
-
 	is_first_job = xa_empty(&vdev->submitted_jobs_xa);
 	ret = xa_alloc_cyclic(&vdev->submitted_jobs_xa, &job->job_id, job, file_priv->job_limit,
 			      &file_priv->job_id_next, GFP_KERNEL);
@@ -626,7 +625,7 @@ static int ivpu_job_submit(struct ivpu_job *job, u8 priority, u32 cmdq_id)
 		ivpu_dbg(vdev, JOB, "Too many active jobs in ctx %d\n",
 			 file_priv->ctx.id);
 		ret = -EBUSY;
-		goto err_unlock_submitted_jobs;
+		goto err_unlock;
 	}
 
 	ret = ivpu_cmdq_push_job(cmdq, job);
@@ -649,22 +648,20 @@ static int ivpu_job_submit(struct ivpu_job *job, u8 priority, u32 cmdq_id)
 		 job->job_id, file_priv->ctx.id, job->engine_idx, cmdq->priority,
 		 job->cmd_buf_vpu_addr, cmdq->jobq->header.tail);
 
-	mutex_unlock(&vdev->submitted_jobs_lock);
 	mutex_unlock(&file_priv->lock);
 
 	if (unlikely(ivpu_test_mode & IVPU_TEST_MODE_NULL_HW)) {
-		mutex_lock(&vdev->submitted_jobs_lock);
 		ivpu_job_signal_and_destroy(vdev, job->job_id, VPU_JSM_STATUS_SUCCESS);
-		mutex_unlock(&vdev->submitted_jobs_lock);
 	}
 
+	mutex_unlock(&vdev->submitted_jobs_lock);
+
 	return 0;
 
 err_erase_xa:
 	xa_erase(&vdev->submitted_jobs_xa, job->job_id);
-err_unlock_submitted_jobs:
+err_unlock:
 	mutex_unlock(&vdev->submitted_jobs_lock);
-err_unlock_file_priv:
 	mutex_unlock(&file_priv->lock);
 	ivpu_rpm_put(vdev);
 	return ret;
-- 
2.43.0