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SubjectRe: [PATCH] drivers/firmware_loader: remove list entry before deallocation
On Mon, Dec 12, 2022 at 06:52:51PM +0100, Michał Lach wrote:
> On 12/12/22 07:04, Luis Chamberlain wrote:
> > Hey Michal! Thanks for your patch! I have a few doubts though!
>
> :-)
>
> > To account for not having to deal with specific drivers we have the
> > Linux kernel selftests. And so you can test the firmware loader with all
> > sorts of crazy situations which any driver could use and try to see
> > if you can re-recreate the issue.
> >
> > The kernel selftests driver for the firmware loader is in
> > lib/test_firmware.c and you can use thetools/testing/selftests/firmware/fw_run_tests.sh
> > to run all the tests. To test the firmware fallback alone you can use
> > just fw_fallback.sh.
> >
> > If you want to just virtualize this and you can also use kdevops [0] and
> > enable the firmware loader selftest and use:;
> >
> > make menuconfig # enable selftests and just the firmware test
> > make linux # build linux, pick linux-next
> > make selftests
> > make selftests-firmware
> >
> > But this may be something more you can use later once you get your flow
> > going. Just compiling the kernel and running the selftest manually with
> > fw_fallback.sh should suffice.
>
> Thanks a lot, I had no idea that there is something like this.

selftests has been there for ages, kdevops support for selftests is
pretty new, like 1 week old only :)

> > OK so this proves the bug can happen but I'd like to see the full trace
> > and the exact kernel version showing that this can happen on a recent
> > kernel. Without that I'm not seeing how this can trigger yet.
>
> Unfortunately I cannot provide a trace. The kernel version was 5.15.41 (-stable).

Ah, I suspected as much, given I couldn't see how this could happen in
linux-next.

> Keeping that in mind, I will try to reproduce this behaviour with in-tree
> code and provide proof.

Yes please use linux-next, if you can't reproduce there then likely
your kernel is missing some fixes.

Luis

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