linux-kernel - [PATCH 4.19 218/361] libnvdimm, region: Fail badblocks listing for inactive regions

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Date:   Sun, 11 Nov 2018 14:19:25 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Johannes Thumshirn <jthumshirn@...e.de>,
        Dave Jiang <dave.jiang@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH 4.19 218/361] libnvdimm, region: Fail badblocks listing for inactive regions

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@...el.com>

commit 5d394eee2c102453278d81d9a7cf94c80253486a upstream.

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@...r.kernel.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/nvdimm/region_devs.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -560,10 +560,17 @@ static ssize_t region_badblocks_show(str
 		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,