Re: [RFC PATCH] vhost-vdpa: mark vhost device invalid to reflect vdpa device unregistration

在 2021/7/5 上午4:52, gautam.dawar@xilinx.com 写道:

Besides the mapping handling mentioned by Michael. I think this can lead 
use-after-free. put_device may release the memory.

Another fundamental issue, vDPA is the parent of vhost-vDPA device. I'm 
not sure the device core can allow the parent to go away first.

Thanks


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在 2021/7/5 上午11:48, Jason Wang 写道:

在 2021/7/5 上午4:52, gautam.dawar@xilinx.com 写道:

quoted

      vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

@@ -1091,11 +1122,13 @@ static void vhost_vdpa_remove(struct 

vdpa_device *vdpa)
          opened = atomic_cmpxchg(&v->opened, 0, 1);
          if (!opened)
              break;
-        wait_for_completion_timeout(&v->completion,
-                        msecs_to_jiffies(1000));
-        dev_warn_once(&v->dev,
-                  "%s waiting for/dev/%s to be closed\n",
-                  __func__, dev_name(&v->dev));
+        if (!wait_for_completion_timeout(&v->completion,
+                        msecs_to_jiffies(1000))) {
+            dev_warn(&v->dev,
+                 "%s/dev/%s in use, continue..\n",
+                 __func__, dev_name(&v->dev));
+            break;
+        }
      } while (1);
        put_device(&v->dev);
+    v->dev_invalid = true;

Besides the mapping handling mentioned by Michael. I think this can 
lead use-after-free. put_device may release the memory.

Another fundamental issue, vDPA is the parent of vhost-vDPA device. 
I'm not sure the device core can allow the parent to go away first.

Or this probably means you need couple the fd loosely with the 
vhost-vDPA device.

Thanks

Thanks

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