FAILED: patch "[PATCH] regulator: avoid resolve_supply() infinite recursion" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4b639e254d3d4f15ee4ff2b890a447204cfbeea9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <[email protected]>
Date: Fri, 13 Nov 2020 01:20:28 +0100
Subject: [PATCH] regulator: avoid resolve_supply() infinite recursion
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When a regulator's name equals its supply's name the regulator_resolve_supply() recurses indefinitely. Add a check so that debugging the problem is easier. The "fixed" commit just exposed the problem.

index 84dd0aea97c5..d3b96efa20fd 100644
@@ -1841,6 +1841,12 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 		}
 	}
 
+	if (r == rdev) {
+		dev_err(dev, "Supply for %s (%s) resolved to itself\n",
+			rdev->desc->name, rdev->supply_name);
+		return -EINVAL;
+	}
+
 	/*
 	 * If the supply's parent device is not the same as the
 	 * regulator's parent device, then ensure the parent device

Hi Greg,

Here is the backport.

--
Regards
Sudip

From 3ef096ea5d9ec8353a23109cd4d8a326743c7905 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <[email protected]>
Date: Fri, 13 Nov 2020 01:20:28 +0100
Subject: [PATCH] regulator: avoid resolve_supply() infinite recursion
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 4b639e254d3d4f15ee4ff2b890a447204cfbeea9 upstream

When a regulator's name equals its supply's name the regulator_resolve_supply() recurses indefinitely. Add a check so that debugging the problem is easier. The "fixed" commit just exposed the problem.

---
 drivers/regulator/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

index 0a0dd0aac047..89f14e301b4c 100644
@@ -1550,6 +1550,12 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 		}
 	}
 
+	if (r == rdev) {
+		dev_err(dev, "Supply for %s (%s) resolved to itself\n",
+			rdev->desc->name, rdev->supply_name);
+		return -EINVAL;
+	}
+
 	/* Recursively resolve the supply of the supply */
 	ret = regulator_resolve_supply(r);
 	if (ret < 0) {

2.11.0