linux-kernel - [PATCH RFC 3/4] dax/cxl: Fix refcount leak in cxl_dax_region

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Message-Id: <20230602-dax-region-put-v1-3-d8668f335d45@intel.com>
Date:   Fri, 02 Jun 2023 19:09:23 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joao Martins <joao.m.martins@...cle.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     Yongqiang Liu <liuyongqiang13@...wei.com>,
        Paul Cassella <cassella@....com>, linux-kernel@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-cxl@...r.kernel.org,
        Ira Weiny <ira.weiny@...el.com>
Subject: [PATCH RFC 3/4] dax/cxl: Fix refcount leak in
 cxl_dax_region_probe()

alloc_dax_region() returns a reference protected dax_region.  Regardless
of the success of the devm_create_dev_dax() the reference returned from
alloc_dax_region() needs to be released.

Drop the dax_region reference regardless of the success of dev_dax
creation.  Clean up comments.

Fixes: 09d09e04d2fc ("cxl/dax: Create dax devices for CXL RAM regions")
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: linux-cxl@...r.kernel.org
Signed-off-by: Ira Weiny <ira.weiny@...el.com>

---
This work was inspired by Yongqiang Liu here:

https://lore.kernel.org/all/20221203095858.612027-1-liuyongqiang13@huawei.com/
---
 drivers/dax/cxl.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index ccdf8de85bd5..bbfe71cf4325 100644
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -29,12 +29,11 @@ static int cxl_dax_region_probe(struct device *dev)
 		.size = range_len(&cxlr_dax->hpa_range),
 	};
 	dev_dax = devm_create_dev_dax(&data);
-	if (IS_ERR(dev_dax))
-		return PTR_ERR(dev_dax);
 
 	/* child dev_dax instances now own the lifetime of the dax_region */
 	dax_region_put(dax_region);
-	return 0;
+
+	return IS_ERR(dev_dax) ? PTR_ERR(dev_dax) : 0;
 }
 
 static struct cxl_driver cxl_dax_region_driver = {

-- 
2.40.0