Messages in this thread | | | Subject | Re: [PATCH 0/2] Fix (improve) deadlock condition on module removal netfilter socket option removal | From | Rusty Russell <> | Date | Thu, 06 Sep 2007 03:41:37 +1000 |
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On Wed, 2007-09-05 at 13:08 -0400, Neil Horman wrote: > On Thu, Sep 06, 2007 at 02:13:26AM +1000, Rusty Russell wrote: > > On Wed, 2007-09-05 at 17:22 +0200, Patrick McHardy wrote: > > > But I'm wondering, wouldn't module refcounting alone fix this problem? > > > If we make nf_sockopt() call try_module_get(ops->owner), remove_module() > > > on ip_tables.ko would simply fail because the refcount is above zero > > > (so it would fail at point 3 above). Am I missing something important? > > > > Yes, that seems the correct solution to me, too. ISTR that this code > > predates the current module code. > > > > Rusty. > > Thanks guys- > When I first started looking at this problem I would have agreed with > you, that module reference counting alone would fix the problem. However, > delete_module can work in either a non-blocking or a blocking mode. rmmod > passes O_NONBLOCK to delete module, and so is fine, but modprobe does not.
Hi Neil,
You have this backwards: O_NONBLOCK is the default. That seems to be what everyone wants, although I implemented 'rmmod -w' because it seemed like a good option.
Rusty.
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