[PATCH V3] accel/amdxdna: Prevent PM resume deadlock in hwctx_sync_debug_bo()

[Lizhi Hou]

amdxdna_hwctx_sync_debug_bo() invokes the hardware hwctx_sync_debug_bo()
callback while holding xdna->dev_lock.

The callback may call amdxdna_cmd_submit(), which in turn calls
amdxdna_pm_resume_get(). If the device is suspended,
amdxdna_pm_resume_get() may synchronously execute amdxdna_pm_resume(),
which also acquires xdna->dev_lock, resulting in a deadlock.

Avoid the deadlock by calling amdxdna_pm_resume_get() before holding
xdna->dev_lock in both amdxdna_hwctx_sync_debug_bo() and
amdxdna_drm_config_hwctx_ioctl()

Fixes: 7ea046838021 ("accel/amdxdna: Support firmware debug buffer")
Signed-off-by: Lizhi Hou <lizhi.hou@xxxxxxx>
---
V2:
  Fix jumping forward over the guard(mutex) declaration.
V3:
  Fix the same in amdxdna_drm_config_hwctx_ioctl().

 drivers/accel/amdxdna/amdxdna_ctx.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/accel/amdxdna/amdxdna_ctx.c b/drivers/accel/amdxdna/amdxdna_ctx.c
index ff6c3e8e5a15..2ab4443e7094 100644
--- a/drivers/accel/amdxdna/amdxdna_ctx.c
+++ b/drivers/accel/amdxdna/amdxdna_ctx.c
@@ -356,16 +356,25 @@ int amdxdna_drm_config_hwctx_ioctl(struct drm_device *dev, void *data, struct dr
 		return -EINVAL;
 	}
 
-	guard(mutex)(&xdna->dev_lock);
+	ret = amdxdna_pm_resume_get(xdna);
+	if (ret) {
+		XDNA_ERR(xdna, "Resume failed, ret %d", ret);
+		goto free_buf;
+	}
+
+	mutex_lock(&xdna->dev_lock);
 	hwctx = xa_load(&client->hwctx_xa, args->handle);
 	if (!hwctx) {
 		XDNA_DBG(xdna, "PID %d failed to get hwctx %d", client->pid, args->handle);
 		ret = -EINVAL;
-		goto free_buf;
+		goto unlock;
 	}
 
 	ret = xdna->dev_info->ops->hwctx_config(hwctx, args->param_type, val, buf, buf_size);
 
+unlock:
+	mutex_unlock(&xdna->dev_lock);
+	amdxdna_pm_suspend_put(xdna);
 free_buf:
 	kfree(buf);
 	return ret;
@@ -386,16 +395,25 @@ int amdxdna_hwctx_sync_debug_bo(struct amdxdna_client *client, u32 debug_bo_hdl)
 	if (!gobj)
 		return -EINVAL;
 
+	ret = amdxdna_pm_resume_get(xdna);
+	if (ret) {
+		XDNA_ERR(xdna, "Resume failed, ret %d", ret);
+		goto put_obj;
+	}
+
 	abo = to_xdna_obj(gobj);
-	guard(mutex)(&xdna->dev_lock);
+	mutex_lock(&xdna->dev_lock);
 	hwctx = xa_load(&client->hwctx_xa, abo->assigned_hwctx);
 	if (!hwctx) {
 		ret = -EINVAL;
-		goto put_obj;
+		goto unlock;
 	}
 
 	ret = xdna->dev_info->ops->hwctx_sync_debug_bo(hwctx, debug_bo_hdl);
 
+unlock:
+	mutex_unlock(&xdna->dev_lock);
+	amdxdna_pm_suspend_put(xdna);
 put_obj:
 	drm_gem_object_put(gobj);
 	return ret;
-- 
2.34.1