linux-kernel - [PATCH 3/4] cxl/mem: Do not rely on device_add() side effects for dev_set

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Date:   Wed, 24 Mar 2021 14:02:01 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-cxl@...r.kernel.org
Cc:     Jason Gunthorpe <jgg@...dia.com>, ira.weiny@...el.com,
        vishal.l.verma@...el.com, alison.schofield@...el.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] cxl/mem: Do not rely on device_add() side effects for
 dev_set_name() failures

While device_add() will happen to catch dev_set_name() failures it is a
broken pattern to follow given that the core may try to fall back to a
different name.

Add explicit checking for dev_set_name() failures to be cleaned up by
put_device(). Skip cdev_device_add() and proceed directly to
put_device() if the name set failure.

Fixes: b39cb1052a5c ("cxl/mem: Register CXL memX devices")
Reported-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/cxl/mem.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index e53d573ae4ab..d615f183520c 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -1204,12 +1204,14 @@ static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
 	dev->bus = &cxl_bus_type;
 	dev->devt = MKDEV(cxl_mem_major, cxlmd->id);
 	dev->type = &cxl_memdev_type;
-	dev_set_name(dev, "mem%d", cxlmd->id);
 
 	cdev = &cxlmd->cdev;
 	cdev_init(cdev, &cxl_memdev_fops);
 
-	rc = cdev_device_add(cdev, dev);
+	rc = dev_set_name(dev, "mem%d", cxlmd->id);
+	if (rc == 0)
+		rc = cdev_device_add(cdev, dev);
+
 	if (rc) {
 		percpu_ref_kill(&cxlmd->ops_active);
 		put_device(dev);