Re: [PATCH net] net/neigh: move neigh cleanup routine to neigh_destroy

[David Miller <davem@xxxxxxxxxxxxx>]

From: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Date: Mon, 23 Apr 2012 18:34:42 +0300

> From: Shlomo Pongratz <shlomop@xxxxxxxxxxxx>
> 
> Move call the neigh_cleanup call to be done from neigh_destroy, this
> ensures the cleanup callback is invoked only when the neighbour reference
> count becomes zero (e.g in the same manner as ndo_neigh_destory).
> 
> Note that with this change neigh_destroy will truly revert the action of
> neigh_create, as neigh_release which calls neigh_destroy is called directly
> from various code paths, and thus neigh->parms->neigh_cleanup is not called
> for these code paths.
> 
> Also, with commit 7d26bb103 "bonding: emit event when bonding changes MAC" that
> triggers netdev address change event, a race was introduced since neigh cleanup
> can be called when there's reference on the neighbour.
> 
> Signed-off-by: Shlomo Pongratz <shlomop@xxxxxxxxxxxx>
> Signed-off-by: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>

With IPOIB, the neigh_cleanup purges references to the neigh when it
liberates the SKBs in the neigh resolution TX backlog during
ipoib_neigh_free().

Therefore, with your change, IPOIB neighs will never be destroyed if
they have any SKBs in their neigh resolution queues.

I'm not applying this, it's buggy.
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