On Wed, Sep 10, 2014 at 01:13:07PM +0200, Pino Toscano wrote:
Swap guestfs_close and free_per_handle_table, so first the handle is
removed from the table and then freed. This avoids passing a stale
pointer to free_per_handle_table (which right now is not an issue, but
better make sure it is never so).
---
Maybe this could also fix the case described by the comment there,
as when a new 'g' with the address of an old 'g' would be created,
the old 'g' is now already gone from the per-handle table.
generator/lua.ml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/generator/lua.ml b/generator/lua.ml
index 5d5619c..fa6e9f2 100644
--- a/generator/lua.ml
+++ b/generator/lua.ml
@@ -168,13 +168,13 @@ guestfs_lua_create (lua_State *L)
static void
close_handle (lua_State *L, guestfs_h *g)
{
- guestfs_close (g);
/* There is a potential and hard-to-solve race here: If another
* thread allocates another 'g' at the same address, then
* get_per_handle_table might be called with the same address
* before we call free_per_handle_table here. XXX
*/
free_per_handle_table (L, g);
+ guestfs_close (g);
}
I have a vague feeling that the order of operations here was important
for some reason. And presumably I wouldn't have written that comment
if the solution was as simple as swapping the two statements around.
So .. not sure. I think we should leave this alone.
I can't find anything in the git commits to indicate what the problem
might have been.
Rich.
--
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