Re: [PATCH] once: Fix panic when module unload

[Kefeng Wang]

On 2021/8/3 17:59, Hannes Frederic Sowa wrote:
> Hello,
>
> On Tue, Aug 3, 2021, at 04:11, Kefeng Wang wrote:
> > Hi ALL, I don't know who maintain the lib/once.c, add Greg and Andrew too,
> >
> > Hi David, I check the history, the lib/once.c is from net/core/utils.c
> > since
> >
> > commit 46234253b9363894a254844a6550b4cc5f3edfe8
> > Author: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
> > Date:   Thu Oct 8 01:20:35 2015 +0200
> >
> >       net: move net_get_random_once to lib
> >
> > This bug is found in our product test, we want to make sure that whether
> > this solution
> >
> > is correct or not, so could David or any others help to review this patch.
> >
> > Many thinks.
> Thanks for the patch.
>
> I see that it got marked as not applicable for the net trees:
> <https://patchwork.kernel.org/project/netdevbpf/patch/20210622022138.23048-1-wangkefeng.wang@xxxxxxxxxx/>
>
> Back then I added this code via the net/ tree thus I think it should get
> picked up nonetheless hopefully.
>
> Regarding your patch, I think it mostly looks fine:
>
> It might be worthwhile to increment the reference counter inside the
> preempt disabled bracket in find_module_by_key (and thus also rename
> that function to make this fact more clear).
>
> The other option would be to use the macro DO_ONCE and always pass in
> THIS_MODULE from there, increment its ref counter in once_disable_jump.
> This might be more canonical.

Thanks for your replay.

Yes, that was my first thought, add THIS_MODULE to __do_once_done(),

I will change to this way to fix the issue.


> Thanks and sorry for the delay,
> Hannes
> .