linux-kernel - [PATCH v2 07/12] cxl: Remove dev_is_cxl_root_child() check in devm_cxl_enumerate

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Date:   Tue, 18 Oct 2022 15:23:35 +0200
From:   Robert Richter <rrichter@....com>
To:     Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        "Davidlohr Bueso" <dave@...olabs.net>,
        Robert Richter <rrichter@....com>
Subject: [PATCH v2 07/12] cxl: Remove dev_is_cxl_root_child() check in devm_cxl_enumerate_ports()

The dev_is_cxl_root_child() check adds complexity to the control flow
of the iterator loop in devm_cxl_enumerate_ports(). This check is
unnecessary and can safely be removed: If the port of a dport_dev is
connected to the cxl root port, the grandparent of dport_dev will be
null. This is checked early in the iterator loop and the function is
left in this case.

Drop this check to ease the control flow in devm_cxl_enumerate_
ports().

This change is a prerequisite of factoring out parts of the loop.

Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/core/port.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 0431ed860d8e..9af2d91db9bf 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1395,6 +1395,7 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 				"found already registered port %s:%s\n",
 				dev_name(&port->dev), dev_name(port->uport));
 			rc = cxl_add_ep(dport, &cxlmd->dev);
+			put_device(&port->dev);
 
 			/*
 			 * If the endpoint already exists in the port's list,
@@ -1403,19 +1404,11 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 			 * the parent_port lock as the current port may be being
 			 * reaped.
 			 */
-			if (rc && rc != -EBUSY) {
-				put_device(&port->dev);
+			if (rc && rc != -EBUSY)
 				return rc;
-			}
 
 			/* Any more ports to add between this one and the root? */
-			if (!dev_is_cxl_root_child(&port->dev)) {
-				put_device(&port->dev);
-				continue;
-			}
-
-			put_device(&port->dev);
-			return 0;
+			continue;
 		}
 
 		rc = add_port_attach_ep(cxlmd, uport_dev, dport_dev);
-- 
2.30.2