[PATCH AUTOSEL 6.1 13/15] nvdimm: rectify the illogical code within nd_dax_probe()

Sasha Levin
2024-12-04T17:02:52Z

From: Yi Yang <yiyang13@huawei.com>

[ Upstream commit b61352101470f8b68c98af674e187cfaa7c43504 ]

When nd_dax is NULL, nd_pfn is consequently NULL as well. Nevertheless,
it is inadvisable to perform pointer arithmetic or address-taking on a
NULL pointer.
Introduce the nd_dax_devinit() function to enhance the code's logic and
improve its readability.

Signed-off-by: Yi Yang <yiyang13@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/20241108085526.527957-1-yiyang13@huawei.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvdimm/dax_devs.c | 4 ++--
drivers/nvdimm/nd.h | 7 +++++++
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c
index 7f4a9d28b6702..5cafca6ba1da3 100644
--- a/drivers/nvdimm/dax_devs.c
+++ b/drivers/nvdimm/dax_devs.c
@@ -106,12 +106,12 @@ int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns)

nvdimm_bus_lock(&ndns->dev);
nd_dax = nd_dax_alloc(nd_region);
- nd_pfn = &nd_dax->nd_pfn;
- dax_dev = nd_pfn_devinit(nd_pfn, ndns);
+ dax_dev = nd_dax_devinit(nd_dax, ndns);
nvdimm_bus_unlock(&ndns->dev);
if (!dax_dev)
return -ENOMEM;
pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
+ nd_pfn = &nd_dax->nd_pfn;
nd_pfn->pfn_sb = pfn_sb;
rc = nd_pfn_validate(nd_pfn, DAX_SIG);
dev_dbg(dev, "dax: %s\n", rc == 0 ? dev_name(dax_dev) : "<none>");
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index ec5219680092d..cce728f5409d6 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -601,6 +601,13 @@ struct nd_dax *to_nd_dax(struct device *dev);
int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns);
bool is_nd_dax(struct device *dev);
struct device *nd_dax_create(struct nd_region *nd_region);
+static inline struct device *nd_dax_devinit(struct nd_dax *nd_dax,
+ struct nd_namespace_common *ndns)
+{
+ if (!nd_dax)
+ return NULL;
+ return nd_pfn_devinit(&nd_dax->nd_pfn, ndns);
+}
#else
static inline int nd_dax_probe(struct device *dev,
struct nd_namespace_common *ndns)
--
2.43.0