linux-kernel - [PATCH v1 3/3] driver core: fw_devlink: Improve logs for cycle detection

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Date: Fri,  2 Feb 2024 01:22:49 -0800
From: Saravana Kannan <saravanak@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>
Cc: Xu Yang <xu.yang_2@....com>, kernel-team@...roid.com, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 3/3] driver core: fw_devlink: Improve logs for cycle detection

The links in a cycle are not all logged in a consistent manner or not
logged at all. Make them consistent and log all the link in the cycles
(even the child ==> parent dependency) so that it's easier to debug cycle
detection code. Also, mark the start and end of a cycle so it's easy to
tell when multiple cycles are logged back to back.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/core.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index e3d666461835..084d9648e254 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -125,7 +125,7 @@ static void __fwnode_link_del(struct fwnode_link *link)
  */
 static void __fwnode_link_cycle(struct fwnode_link *link)
 {
-	pr_debug("%pfwf: Relaxing link with %pfwf\n",
+	pr_debug("%pfwf: cycle: depends on %pfwf\n",
 		 link->consumer, link->supplier);
 	link->flags |= FWLINK_FLAG_CYCLE;
 }
@@ -1945,6 +1945,7 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 
 	/* Termination condition. */
 	if (sup_dev == con) {
+		pr_debug("----- cycle: start -----\n");
 		ret = true;
 		goto out;
 	}
@@ -1976,8 +1977,11 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 	else
 		par_dev = fwnode_get_next_parent_dev(sup_handle);
 
-	if (par_dev && __fw_devlink_relax_cycles(con, par_dev->fwnode))
+	if (par_dev && __fw_devlink_relax_cycles(con, par_dev->fwnode)) {
+		pr_debug("%pfwf: cycle: depends on %pfwf\n", sup_handle,
+			 par_dev->fwnode);
 		ret = true;
+	}
 
 	if (!sup_dev)
 		goto out;
@@ -1993,6 +1997,8 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 
 		if (__fw_devlink_relax_cycles(con,
 					      dev_link->supplier->fwnode)) {
+			pr_debug("%pfwf: cycle: depends on %pfwf\n", sup_handle,
+				 dev_link->supplier->fwnode);
 			fw_devlink_relax_link(dev_link);
 			dev_link->flags |= DL_FLAG_CYCLE;
 			ret = true;
@@ -2072,6 +2078,7 @@ static int fw_devlink_create_devlink(struct device *con,
 		if (__fw_devlink_relax_cycles(con, sup_handle)) {
 			__fwnode_link_cycle(link);
 			flags = fw_devlink_get_flags(link->flags);
+			pr_debug("----- cycle: end -----\n");
 			dev_info(con, "Fixed dependency cycle(s) with %pfwf\n",
 				 sup_handle);
 		}
-- 
2.43.0.594.gd9cf4e227d-goog