Re: [PATCH rdma-next] RDMA/nldev: Fix section mismatch warning for nldev

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Oct 28, 2022 at 07:47:53PM +0300, Leon Romanovsky wrote:
> On Fri, Oct 28, 2022 at 01:34:57PM -0300, Jason Gunthorpe wrote:
> > On Fri, Oct 28, 2022 at 07:19:36PM +0300, Leon Romanovsky wrote:
> > > On Fri, Oct 28, 2022 at 01:15:16PM -0300, Jason Gunthorpe wrote:
> > > > On Fri, Oct 28, 2022 at 07:14:16PM +0300, Leon Romanovsky wrote:
> > > > > On Fri, Oct 28, 2022 at 01:00:27PM -0300, Jason Gunthorpe wrote:
> > > > > > On Fri, Oct 28, 2022 at 09:58:56AM +0300, Leon Romanovsky wrote:
> > > > > > > ppc64_defconfig) produced this warning:
> > > > > > > 
> > > > > > > WARNING: modpost: drivers/infiniband/core/ib_core.o: section mismatch in reference: .init_module (section: .init.text) -> .nldev_exit (section: .exit.text)
> > > > > > > 
> > > > > > > Fix it by removing __init/__exit markers as nldev is part of ib_core.ko
> > > > > > > and as such doesn't require any special notations for entry/exit functions.
> > > > > > 
> > > > > > This isn't what the problem is, the patch Stephen reported:
> > > > > > 
> > > > > > commit ad9394a3da33995dff828dbfd4540421e535bec9 (ko-rdma/for-rc)
> > > > > > Author: Chen Zhongjin <chenzhongjin@huawei.com>
> > > > > > Date:   Tue Oct 25 10:41:46 2022 +0800
> > > > > > 
> > > > > >     RDMA/core: Fix null-ptr-deref in ib_core_cleanup()
> > > > > > 
> > > > > > Adds a call to an __exit function from an __init function:
> > > > > > 
> > > > > > @@ -2815,10 +2815,18 @@ static int __init ib_core_init(void)
> > > > > > 
> > > > > > +err_parent:
> > > > > > +       rdma_nl_unregister(RDMA_NL_LS);
> > > > > > +       nldev_exit();
> > > > > > +       unregister_pernet_device(&rdma_dev_net_ops);
> > > > > > 
> > > > > > Which is not allowed
> > > > > > 
> > > > > > All that is required is to drop the __exit from nldev_exit, 
> > > > > 
> > > > > This is why I dropped both __exit and __init. I see no value in keeping
> > > > > __init, without __exit.
> > > > 
> > > > __init works just fine, it will cause the code to be unload after the
> > > > module registration is compelted
> > > 
> > > The code will be unloaded as part of ib_core unload. It is not different
> > > from any other function call in ib_core_init() which is marked as __init.
> > 
> > Huh?
> > 
> > Only things marked __init are discarded after module load
> 
> nldev_init() has single call to rdma_nl_register(), which part of ib_core_init() too.
> There is nothing to discard.

It discards the one statement function since it cannot be inlined.

Jason