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

[Jürgen Groß]

On 03.12.20 16:29, Jan Beulich wrote:

On 03.12.2020 16:14, Jürgen Groß wrote:

On 03.12.20 15:59, 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;
+
+    return 0;
+}
+
+static void node_exit(const struct hypfs_entry *entry)
+{
+    const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
+
+    if ( !*last )
+        return;

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

Under what conditions is this legitimate to happen? IOW shouldn't
there be an ASSERT_UNREACHABLE() here?

This is for the "/" node.

I.e. would ASSERT(!entry->parent) be appropriate to add here, at
the same time serving as documentation of what you've just said?

I rechecked and have found that this was a remnant from an earlier
variant. *last won't ever be NULL, so the if can be dropped (a NULL
will be catched by the following ASSERT()).


Juergen

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