Hi Miquel,
On Fri, 7 Sep 2018 16:38:24 +0200
Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> Hello,
>
> I forgot to add Rafal which I know worked a lot on the parsers.
>
> Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote on Fri, 7 Sep 2018
> 16:35:54 +0200:
>
> > While at first mtd_part_of_parse() would just call
> > of_get_chil_by_name(), it has been edited to first try to get the OF
> > node thanks to mtd_get_of_node() and fallback on
> > of_get_child_by_name().
> >
> > A of_node_put() was a bit below in the code, to balance the
> > of_get_child_by_name(). However, despite its name, mtd_get_of_node()
> > does not take a reference on the OF node.
That's probably something we should patch at some point, but that
implies patching all mtd_get_of_node() users at the same time, so let's
keep that for later.
BTW, if mtd_get_of_node() was actually retaining a reference, you
would miss an of_node_put() in the !mtd_is_partition(master) case.
> > It is a simple helper hiding
> > some pointer logic to retrieve the OF node related to an MTD
> > device. People often used it this way:
> >
> > of_node_put(mtd_get_of_node(<mtd>)).
I don't get your point. Are you saying other places in the code are
doing the wrong thing? Should we fix them too?
> >
> > The direct effect of such unbalanced reference counting is visible by
> > rmmod'ing any module that would have added MTD partitions:
> >
> > OF: ERROR: Bad of_node_put() on <of_path_to_partition>
> >
> > As it seems normal to get a reference on the OF node during the
> > of_property_for_each_string() that follows, add a call to
> > of_node_get() when relevant.
> >
> > Fixes: 76a832254ab0 ("mtd: partitions: use DT info for parsing partitions with "compatible" prop")
> > Cc: stable@xxxxxxxxxxxxxxx
You can drop the above line since this patch is fixing a bug introduced
in 4.19-rc1.
> > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > ---
> > drivers/mtd/mtdpart.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> > index 52e2cb35fc79..99c460facd5e 100644
> > --- a/drivers/mtd/mtdpart.c
> > +++ b/drivers/mtd/mtdpart.c
> > @@ -873,8 +873,11 @@ static int mtd_part_of_parse(struct mtd_info *master,
> > int ret, err = 0;
> >
> > np = mtd_get_of_node(master);
> > - if (!mtd_is_partition(master))
> > + if (mtd_is_partition(master))
> > + of_node_get(np);
> > + else
> > np = of_get_child_by_name(np, "partitions");
> > +
> > of_property_for_each_string(np, "compatible", prop, compat) {
> > parser = mtd_part_get_compatible_parser(compat);
> > if (!parser)
The patch itself looks correct, but I'd like some clarification about
the commit message before applying it.
Thanks,
Boris
--
Boris Brezillon, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
