Re: [PATCH v2 2/4] ubi: ubi_init: Fix missed ubiblock cleanup in error handling path

[Zhihao Cheng]

在 2024/4/11 23:48, Daniel Golle 写道:
> On Thu, Apr 11, 2024 at 11:19:01AM +0800, Zhihao Cheng wrote:
> > The ubiblock_init called by ubi_init will register device number, but
> > device number is not released in error handling path of ubi_init when
> > ubi is loaded by inserting module (eg. attaching failure), which leads
> > to subsequent ubi_init calls failed by running out of device number
> > (dmesg shows that "__register_blkdev: failed to get major for ubiblock").
> > Since ubiblock_init() registers notifier and invokes notification
> > functions, so we can move it after ubi_init_attach() to fix the problem.
> >
> > Fixes: 927c145208b0 ("mtd: ubi: attach from device tree")
> > Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
> > ---
> >   drivers/mtd/ubi/build.c | 51 +++++++++++++++++++++--------------------
> >   1 file changed, 26 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
> > index 7f95fd7968a8..bc63fbf5e947 100644
> > --- a/drivers/mtd/ubi/build.c
> > +++ b/drivers/mtd/ubi/build.c
> > @@ -1263,9 +1263,21 @@ static struct mtd_notifier ubi_mtd_notifier = {
> >   	.remove = ubi_notify_remove,
> >   };
> >   
> > +static void detach_mtd_devs(int count)
>
> Missing __init to avoid section missmatch.
>
> See also: https://lore.kernel.org/oe-kbuild-all/202404112327.158HJfAw-lkp@xxxxxxxxx/

I think function without '__init' attributes can be called in ubi_init, 
for example misc_register, kmem_cache_create, and I verify it by make 
W=1 in local machine. And above warning(in your link) is only detected 
in my v1 series.
After investigating the '__init' and '__exit', I understand that there 
are two independent text section for these functions, for example, 
__init text section will be removed from memory after it is finished, so 
we cannot call __exit function in __init function.
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < count; i++)
> > +		if (ubi_devices[i]) {
> > +			mutex_lock(&ubi_devices_mutex);
> > +			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
> > +			mutex_unlock(&ubi_devices_mutex);
> > +		}
> > +}