drm/i915/gvt: fix lock not released bug for dispatch_workload() err path

Need to be careful to release struct_mutext when request alloc
failed and take consistent handling for return status as with
normal go out path. Ensure to check correct workload request in
complete path too.

v2: Add Fixes note

Fixes: 90d27a1b180e ("drm/i915/gvt: fix deadlock in workload_thread")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Pei Zhang <pei.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index f898df38dd9a..4db242250235 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -177,8 +177,8 @@ static int dispatch_workload(struct intel_vgpu_workload *workload)
         rq = i915_gem_request_alloc(dev_priv->engine[ring_id], shadow_ctx);
         if (IS_ERR(rq)) {
                 gvt_err("fail to allocate gem request\n");
-                workload->status = PTR_ERR(rq);
-                return workload->status;
+                ret = PTR_ERR(rq);
+                goto out;
         }
 
         gvt_dbg_sched("ring id %d get i915 gem request %p\n", ring_id, rq);
@@ -212,7 +212,8 @@ out:
         if (ret)
                 workload->status = ret;
 
-        i915_add_request_no_flush(rq);
+        if (!IS_ERR_OR_NULL(rq))
+                i915_add_request_no_flush(rq);
         mutex_unlock(&dev_priv->drm.struct_mutex);
         return ret;
 }
@@ -460,7 +461,8 @@ complete:
 
                 complete_current_workload(gvt, ring_id);
 
-                i915_gem_request_put(fetch_and_zero(&workload->req));
+                if (workload->req)
+                        i915_gem_request_put(fetch_and_zero(&workload->req));
 
                 if (need_force_wake)
                         intel_uncore_forcewake_put(gvt->dev_priv,