Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm fixes from Dan Williams:
 "A build fix, a NULL de-reference found by static analysis, a misuse of
  the percpu_ref_exit() (tagged for -stable), and notification of failed
  attempts to clear media errors.

  These patches have received a build success notification from the
  0day- kbuild-robot and appeared in next-20161028"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  device-dax: fix percpu_ref_exit ordering
  nvdimm: make CONFIG_NVDIMM_DAX 'bool'
  pmem: report error on clear poison failure
  libnvdimm, namespace: potential NULL deref on allocation error

drivers/dax/Kconfig

@@ -14,7 +14,7 @@ if DEV_DAX
 
 config DEV_DAX_PMEM
 	tristate "PMEM DAX: direct access to persistent memory"
-	depends on NVDIMM_DAX
+	depends on LIBNVDIMM && NVDIMM_DAX
 	default DEV_DAX
 	help
 	  Support raw access to persistent memory.  Note that this

drivers/dax/pmem.c

@@ -44,7 +44,6 @@ static void dax_pmem_percpu_exit(void *data)
 
 	dev_dbg(dax_pmem->dev, "%s\n", __func__);
 	percpu_ref_exit(ref);
-	wait_for_completion(&dax_pmem->cmp);
 }
 
 static void dax_pmem_percpu_kill(void *data)
@@ -54,6 +53,7 @@ static void dax_pmem_percpu_kill(void *data)
 
 	dev_dbg(dax_pmem->dev, "%s\n", __func__);
 	percpu_ref_kill(ref);
+	wait_for_completion(&dax_pmem->cmp);
 }
 
 static int dax_pmem_probe(struct device *dev)

drivers/nvdimm/Kconfig

@@ -89,7 +89,7 @@ config NVDIMM_PFN
 	  Select Y if unsure
 
 config NVDIMM_DAX
-	tristate "NVDIMM DAX: Raw access to persistent memory"
+	bool "NVDIMM DAX: Raw access to persistent memory"
 	default LIBNVDIMM
 	depends on NVDIMM_PFN
 	help

drivers/nvdimm/namespace_devs.c

@@ -2176,12 +2176,14 @@ static struct device **scan_labels(struct nd_region *nd_region)
 	return devs;
 
  err:
+	if (devs) {
 		for (i = 0; devs[i]; i++)
 			if (is_nd_blk(&nd_region->dev))
 				namespace_blk_release(devs[i]);
 			else
 				namespace_pmem_release(devs[i]);
 		kfree(devs);
+	}
 	return NULL;
 }
 

drivers/nvdimm/pmem.c

@@ -47,7 +47,7 @@ static struct nd_region *to_region(struct pmem_device *pmem)
 	return to_nd_region(to_dev(pmem)->parent);
 }
 
-static void pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
+static int pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
 		unsigned int len)
 {
 	struct device *dev = to_dev(pmem);
@@ -62,8 +62,12 @@ static void pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
 				__func__, (unsigned long long) sector,
 				cleared / 512, cleared / 512 > 1 ? "s" : "");
 		badblocks_clear(&pmem->bb, sector, cleared / 512);
+	} else {
+		return -EIO;
 	}
+
 	invalidate_pmem(pmem->virt_addr + offset, len);
+	return 0;
 }
 
 static void write_pmem(void *pmem_addr, struct page *page,
@@ -123,7 +127,7 @@ static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 		flush_dcache_page(page);
 		write_pmem(pmem_addr, page, off, len);
 		if (unlikely(bad_pmem)) {
-			pmem_clear_poison(pmem, pmem_off, len);
+			rc = pmem_clear_poison(pmem, pmem_off, len);
 			write_pmem(pmem_addr, page, off, len);
 		}
 	}