Re: [PATCH v2 12/17] xen/hypfs: add new enter() and exit() per node callbacks

[Jürgen Groß]

On 04.12.20 09:30, Jan Beulich wrote:

On 01.12.2020 09:21, Juergen Gross wrote:

@@ -100,11 +112,58 @@ static void hypfs_unlock(void)
      }
  }

+{
+    return entry;
+}
+
+void hypfs_node_exit(const struct hypfs_entry *entry)
+{
+}
+
+static int node_enter(const struct hypfs_entry *entry)
+{
+    const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
+
+    entry = entry->funcs->enter(entry);
+    if ( IS_ERR(entry) )
+        return PTR_ERR(entry);
+
+    ASSERT(!*last || *last == entry->parent);
+
+    *last = entry;

+const struct hypfs_entry *hypfs_node_enter(const struct hypfs_entry *entry)

In such a callback case I wonder whether you wouldn't want to also
guard against NULL coming back, perhaps simply by mistake, but of
course once handling it here such could even become permissible
behavior.

I think you are right. I should add an ASSERT(entry);


Juergen

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