libnvdimm, pmem: fix a NULL pointer BUG in nd_pmem_notify

The following BUG was observed when nd_pmem_notify() was called
for a BTT device.  The use of a pmem_device pointer is not valid
with BTT.

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
 IP: nd_pmem_notify+0x30/0xf0 [nd_pmem]
 Call Trace:
  nd_device_notify+0x40/0x50
  child_notify+0x10/0x20
  device_for_each_child+0x50/0x90
  nd_region_notify+0x20/0x30
  nd_device_notify+0x40/0x50
  nvdimm_region_notify+0x27/0x30
  acpi_nfit_scrub+0x341/0x590 [nfit]
  process_one_work+0x197/0x450
  worker_thread+0x4e/0x4a0
  kthread+0x109/0x140

Fix nd_pmem_notify() by setting nd_region and badblocks pointers
properly for BTT.

Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Fixes: 719994660c24 ("libnvdimm: async notification support")
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 5b536be..0fc1826 100644 (file)
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -388,12 +388,12 @@ static void nd_pmem_shutdown(struct device *dev)
 
 static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
 {
-       struct pmem_device *pmem = dev_get_drvdata(dev);
-       struct nd_region *nd_region = to_region(pmem);
+       struct nd_region *nd_region;
        resource_size_t offset = 0, end_trunc = 0;
        struct nd_namespace_common *ndns;
        struct nd_namespace_io *nsio;
        struct resource res;
+       struct badblocks *bb;
 
        if (event != NVDIMM_REVALIDATE_POISON)
                return;
@@ -402,20 +402,33 @@ static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
                struct nd_btt *nd_btt = to_nd_btt(dev);
 
                ndns = nd_btt->ndns;
-       } else if (is_nd_pfn(dev)) {
-               struct nd_pfn *nd_pfn = to_nd_pfn(dev);
-               struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+               nd_region = to_nd_region(ndns->dev.parent);
+               nsio = to_nd_namespace_io(&ndns->dev);
+               bb = &nsio->bb;
+       } else {
+               struct pmem_device *pmem = dev_get_drvdata(dev);
 
-               ndns = nd_pfn->ndns;
-               offset = pmem->data_offset + __le32_to_cpu(pfn_sb->start_pad);
-               end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
-       } else
-               ndns = to_ndns(dev);
+               nd_region = to_region(pmem);
+               bb = &pmem->bb;
+
+               if (is_nd_pfn(dev)) {
+                       struct nd_pfn *nd_pfn = to_nd_pfn(dev);
+                       struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+
+                       ndns = nd_pfn->ndns;
+                       offset = pmem->data_offset +
+                                       __le32_to_cpu(pfn_sb->start_pad);
+                       end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
+               } else {
+                       ndns = to_ndns(dev);
+               }
+
+               nsio = to_nd_namespace_io(&ndns->dev);
+       }
 
-       nsio = to_nd_namespace_io(&ndns->dev);
        res.start = nsio->res.start + offset;
        res.end = nsio->res.end - end_trunc;
-       nvdimm_badblocks_populate(nd_region, &pmem->bb, &res);
+       nvdimm_badblocks_populate(nd_region, bb, &res);
 }
 
 MODULE_ALIAS("pmem");