On Tue, 26 Jun 2018 09:10:05 +0200
Miquel Raynal <miquel.ray...@bootlin.com> wrote:
> Hi Martin, Boris,
>
> On Fri, 22 Jun 2018 16:50:25 +0200, Martin Kaiser <mar...@kaiser.cx>
> wrote:
>
> > mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init.
> >
>
> I think this line is just a side note and should be at the end of the
> commit log.
>
> > Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> > potentially be called at any time. After the __init functions are cleaned,
> > mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.
>
> The above paragraph explains the problem and the solution, you can just
> add something like "mcvnd_probe is untouched because it is already not
> marked as __init" instead of the first line.
>
> >
> > Signed-off-by: Martin Kaiser <mar...@kaiser.cx>
>
> Boris, do you think this patch is a good candidate for stable?
>
> If yes, Martin, could you please add a couple of stable/fixes tags above
> your SoB?
We should at least have a Fixes tag. For the stable one, I'm not so
sure because the bug does not exist in practice (the compiler always
inline mxcnd_probe_dt()).
>
> Thanks,
> Miquèl
>
> > ---
> > I hope that my understanding is correct.
> >
> > In practice, I could not get the kernel to crash, my compiler would
> > inline mxcnd_probe_dt into mxcnd_probe and ignore the __init.
> >
> > If I marked mxcnd_probe_dt as noinline, I could trigger a crash as
> > follows
> >
> > [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/unbind
> > [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/bind
> > Internal error: Oops - undefined instruction: 0 [#1] ARM
> > ...
> >
> > drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/raw/mxc_nand.c
> > b/drivers/mtd/nand/raw/mxc_nand.c
> > index 26cef21..90cfb5e 100644
> > --- a/drivers/mtd/nand/raw/mxc_nand.c
> > +++ b/drivers/mtd/nand/raw/mxc_nand.c
> > @@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
> > };
> > MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
> >
> > -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> > +static int mxcnd_probe_dt(struct mxc_nand_host *host)
> > {
> > struct device_node *np = host->dev->of_node;
> > const struct of_device_id *of_id =
> > @@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host
> > *host)
> > return 0;
> > }
> > #else
> > -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> > +static int mxcnd_probe_dt(struct mxc_nand_host *host)
> > {
> > return 1;
> > }
