Messages in this thread | | | Date | Thu, 6 Sep 2018 13:21:01 +0200 | From | Lukas Wunner <> | Subject | Re: [PATCH 2/2] thunderbolt: Initialize after IOMMUs |
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On Thu, Sep 06, 2018 at 02:07:56PM +0300, Mika Westerberg wrote: > On Thu, Sep 06, 2018 at 01:00:49PM +0200, Lukas Wunner wrote: > > On Thu, Sep 06, 2018 at 01:36:02PM +0300, Mika Westerberg wrote: > > > On Thu, Sep 06, 2018 at 10:13:37AM +0200, Lukas Wunner wrote: > > > > So with this patch, you rely on the linker ordering nhi_init() after > > > > ir_dev_scope_init(), however to the best of my knowledge the link > > > > order is not guaranteed. > > > > > > What says that? > > > > Within the same initcall level, the ordering is determined by the Makefile > > AFAIK. Someone changes the Makefile, your dependency scheme falls apart. > > There are other drivers doing the same so they would fail as well. It is > common practice AFAIK.
That doesn't make it a *good* practice.
> > > > Looking at commit acb40d841257, which started this, I'm wondering > > > > why you did not simply export tbnet_init() and call it from the > > > > thunderbolt driver after the property stuff has been fully set up? > > > > After all, thunderbolt-net is useless without thunderbolt or am I > > > > missing something? Then you could revert back to module_init(). > > > > > > The same reason you don't call PCI driver functions from PCI core. It > > > makes absolutely zero sense. > > > > > > Thunderbolt is bus and provides driver API to drivers. We hopefully are > > > getting other service drivers (say SCSI over TBT) that are going to be > > > use the same interfaces. > > > > Then add a blocking notifier chain into which these service drivers can > > hook. Other buses have that as well. > > It is really too complex to add notifier just for that. This works fine > and is not against any kernel principles I am aware of.
Well, there's a difference between "it works and gets the job done, let's move on" and "let's try to find a solution that fixes not just this use case but potentially benefits others as well".
FWIW, what I had in mind is a blocking notifier chain that gets called when a bus registers or unregisters. TB service drivers would then check if it's tb_bus_type and start initialization.
Thanks,
Lukas
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