Messages in this thread | | | Subject | Re: [PATCH 3.16.y-ckt 009/126] sit: fix sit0 percpu double allocations | From | Eric Dumazet <> | Date | Sun, 13 Dec 2015 14:45:47 -0800 |
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On Sun, 2015-12-13 at 21:49 +0000, Ben Hutchings wrote: > On Sun, 2015-12-13 at 13:44 -0800, Eric Dumazet wrote: > > On Sun, 2015-12-13 at 21:22 +0000, Ben Hutchings wrote: > > > On Sun, 2015-12-13 at 12:43 -0800, Eric Dumazet wrote: > > > > > > 1) Sorry Ben, I do not understand the problem you mention. > > > > What is a partially initialized device exactly ? > > > > > > A tunnel device which is registered but hasn't had its private > > > structure fully initialised yet. > > > > And you see this happening after my patch ? I am blind. > > > > I am referring to current linux kernel, not to a backport to pre 3.18 > > kernels, that was not considered when I wrote this patch. > > > > By the time ipip6_fb_tunnel_init() is called, dev->tstats had been > > already allocated in ipip6_tunnel_init(), so what is missing ? > > You moved this initialisation below the registration: > > > ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn); > > ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
Okay, so what is the exact problem you are seeing Ben ?
ipip6_tunnel_clone_6rd() looks to not contain a fatal race or mem leak.
Note that ipip6_tunnel_clone_6rd() can be called later from ioctl() path.
ipip6_fb_tunnel_init() must be done once device is ready, as it publishes state for packet processing.
rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
Looks like a rather correct way to register a device : init all fields, then publish the RCU protected pointer for packets to catch it.
Really, I do not see a problem, please elaborate.
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