On 09/28/2018 11:04 AM, Dan Williams wrote:
> While experimenting with region driver loading the following backtrace
> was triggered:
>
> INFO: trying to register non-static key.
> the code is fine but needs lockdep annotation.
> turning off the locking correctness validator.
> [..]
> Call Trace:
> dump_stack+0x85/0xcb
> register_lock_class+0x571/0x580
> ? __lock_acquire+0x2ba/0x1310
> ? kernfs_seq_start+0x2a/0x80
> __lock_acquire+0xd4/0x1310
> ? dev_attr_show+0x1c/0x50
> ? __lock_acquire+0x2ba/0x1310
> ? kernfs_seq_start+0x2a/0x80
> ? lock_acquire+0x9e/0x1a0
> lock_acquire+0x9e/0x1a0
> ? dev_attr_show+0x1c/0x50
> badblocks_show+0x70/0x190
> ? dev_attr_show+0x1c/0x50
> dev_attr_show+0x1c/0x50
>
> This results from a missing successful call to devm_init_badblocks()
> from nd_region_probe(). Block attempts to show badblocks while the
> region is not enabled.
>
> Fixes: 6a6bef90425e ("libnvdimm: add mechanism to publish badblocks...")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
> Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> ---
> drivers/nvdimm/region_devs.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index fa37afcd43ff..174a418cb171 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -560,10 +560,17 @@ static ssize_t region_badblocks_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct nd_region *nd_region = to_nd_region(dev);
> + ssize_t rc;
>
> - return badblocks_show(&nd_region->bb, buf, 0);
> -}
> + device_lock(dev);
> + if (dev->driver)
> + rc = badblocks_show(&nd_region->bb, buf, 0);
> + else
> + rc = -ENXIO;
> + device_unlock(dev);
>
> + return rc;
> +}
> static DEVICE_ATTR(badblocks, 0444, region_badblocks_show, NULL);
>
> static ssize_t resource_show(struct device *dev,
>
