linux-kernel - [PATCH v2 2/2] regulator: core: Streamline debugfs operations

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Message-Id: <adb012e80899ab9f5dfc80cfed7beb8406993e8e.1684930647.git.geert+renesas@glider.be>
Date:   Wed, 24 May 2023 14:22:18 +0200
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Osama Muhammad <osmtendev@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH v2 2/2] regulator: core: Streamline debugfs operations

If CONFIG_DEBUG_FS is not set:

    regulator: Failed to create debugfs directory
    ...
    regulator-dummy: Failed to create debugfs directory

As per the comments for debugfs_create_dir(), errors returned by this
function should be expected, and ignored:

 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 * returned.
 *
 * NOTE: it's expected that most callers should _ignore_ the errors returned
 * by this function. Other debugfs functions handle the fact that the "dentry"
 * passed to them could be an error and they don't crash in that case.
 * Drivers should generally work fine even if debugfs fails to init anyway.

Adhere to the debugfs spirit, and streamline all operations by:
  1. Demoting the importance of the printed error messages to debug
     level, like is already done in create_regulator(),
  2. Further ignoring any returned errors, as by design, all debugfs
     functions are no-ops when passed an error pointer.

Fixes: 2bf1c45be3b8f3a3 ("regulator: Fix error checking for debugfs_create_dir")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
v2:
  - Spin off error check fix into a separate patch,
  - Improve rationale.
---
 drivers/regulator/core.c | 28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index ad8baf65f63e369b..d8e1caaf207e108f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1913,17 +1913,15 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 		regulator->debugfs = debugfs_create_dir(supply_name, rdev->debugfs);
 	if (IS_ERR(regulator->debugfs))
 		rdev_dbg(rdev, "Failed to create debugfs directory\n");
-	} else {
-		debugfs_create_u32("uA_load", 0444, regulator->debugfs,
-				   &regulator->uA_load);
-		debugfs_create_u32("min_uV", 0444, regulator->debugfs,
-				   &regulator->voltage[PM_SUSPEND_ON].min_uV);
-		debugfs_create_u32("max_uV", 0444, regulator->debugfs,
-				   &regulator->voltage[PM_SUSPEND_ON].max_uV);
-		debugfs_create_file("constraint_flags", 0444,
-				    regulator->debugfs, regulator,
-				    &constraint_flags_fops);
-	}
+
+	debugfs_create_u32("uA_load", 0444, regulator->debugfs,
+			   &regulator->uA_load);
+	debugfs_create_u32("min_uV", 0444, regulator->debugfs,
+			   &regulator->voltage[PM_SUSPEND_ON].min_uV);
+	debugfs_create_u32("max_uV", 0444, regulator->debugfs,
+			   &regulator->voltage[PM_SUSPEND_ON].max_uV);
+	debugfs_create_file("constraint_flags", 0444, regulator->debugfs,
+			    regulator, &constraint_flags_fops);
 
 	/*
 	 * Check now if the regulator is an always on regulator - if
@@ -5256,10 +5254,8 @@ static void rdev_init_debugfs(struct regulator_dev *rdev)
 	}
 
 	rdev->debugfs = debugfs_create_dir(rname, debugfs_root);
-	if (IS_ERR(rdev->debugfs)) {
-		rdev_warn(rdev, "Failed to create debugfs directory\n");
-		return;
-	}
+	if (IS_ERR(rdev->debugfs))
+		rdev_dbg(rdev, "Failed to create debugfs directory\n");
 
 	debugfs_create_u32("use_count", 0444, rdev->debugfs,
 			   &rdev->use_count);
@@ -6179,7 +6175,7 @@ static int __init regulator_init(void)
 
 	debugfs_root = debugfs_create_dir("regulator", NULL);
 	if (IS_ERR(debugfs_root))
-		pr_warn("regulator: Failed to create debugfs directory\n");
+		pr_debug("regulator: Failed to create debugfs directory\n");
 
 #ifdef CONFIG_DEBUG_FS
 	debugfs_create_file("supply_map", 0444, debugfs_root, NULL,
-- 
2.34.1