FAILED: patch "[PATCH] i2c: core: fix adapter deregistration race" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x b1a58ed9eab146b36f41a55db8f5d7ce9fdedf3f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026071601-remnant-map-dbc0@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From b1a58ed9eab146b36f41a55db8f5d7ce9fdedf3f Mon Sep 17 00:00:00 2001
From: Johan Hovold <[email protected]>
Date: Mon, 11 May 2026 16:37:13 +0200
Subject: [PATCH] i2c: core: fix adapter deregistration race

Adapters can be looked up by their id using i2c_get_adapter() which takes a reference to the embedded struct device.

Remove the adapter from the IDR before tearing it down during deregistration (and on registration failure) to make sure its resources are not accessed after having been freed (e.g. the device name).

index 01a984d3ca0e..38f425aecef8 100644
@@ -1587,7 +1587,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	res = device_add(&adap->dev);
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
-		goto err_remove_debugfs;
+		goto err_replace_id;
 	}
 
 	res = i2c_setup_smbus_alert(adap);

@@ -1614,7 +1614,10 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 out_reg:
 	i2c_deregister_clients(adap);
 	device_del(&adap->dev);
-err_remove_debugfs:
+err_replace_id:
+	mutex_lock(&core_lock);
+	idr_replace(&i2c_adapter_idr, NULL, adap->nr);
+	mutex_unlock(&core_lock);
 	debugfs_remove_recursive(adap->debugfs);
 	pm_runtime_disable(&adap->dev);
 err_put_adap:

@@ -1804,6 +1807,8 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 	/* First make sure that this adapter was ever added */
 	mutex_lock(&core_lock);
 	found = idr_find(&i2c_adapter_idr, adap->nr);
+	if (found == adap)
+		idr_replace(&i2c_adapter_idr, NULL, adap->nr);
 	mutex_unlock(&core_lock);
 	if (found != adap) {
 		pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);