FAILED: patch "[PATCH] hwmon: (pmbus/adm1266) serialize sequencer_state debugfs read" failed to apply to 6.12-stable tree

The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 4e4af55aaca7f6d7673d5f9889ad0529db86a048
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026052823-finalize-overprice-3c30@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 4e4af55aaca7f6d7673d5f9889ad0529db86a048 Mon Sep 17 00:00:00 2001
From: Abdurrahman Hussain <[email protected]>
Date: Mon, 18 May 2026 17:52:32 -0700
Subject: [PATCH] hwmon: (pmbus/adm1266) serialize sequencer_state debugfs read
with pmbus_lock

adm1266_state_read() backs the sequencer_state debugfs entry and issues an i2c_smbus_read_word_data(client, ADM1266_READ_STATE) against the device without taking pmbus_lock. pmbus_core holds pmbus_lock around its own multi-transaction sequences (notably the "set PAGE, then read paged register" pattern used by hwmon attributes), so an unlocked debugfs reader can land between a PAGE write and the subsequent paged read in another thread. READ_STATE itself is not paged, so it cannot corrupt PAGE in flight, but the same defensive serialisation that applies to the GPIO accessors applies here: any direct device access from outside pmbus_core should be ordered with respect to pmbus_core's own.

Take pmbus_lock at the top of adm1266_state_read() via the scope-based guard().

index 5ddca5701032..6f6ad7b20e9a 100644
@@ -335,6 +335,7 @@ static int adm1266_state_read(struct seq_file *s, void *pdata)
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;
 
+	guard(pmbus_lock)(client);
 	ret = i2c_smbus_read_word_data(client, ADM1266_READ_STATE);
 	if (ret < 0)
 		return ret;

From: Abdurrahman Hussain <[email protected]>

[ Upstream commit 4e4af55aaca7f6d7673d5f9889ad0529db86a048 ]

adm1266_state_read() backs the sequencer_state debugfs entry and issues an i2c_smbus_read_word_data(client, ADM1266_READ_STATE) against the device without taking pmbus_lock. pmbus_core holds pmbus_lock around its own multi-transaction sequences (notably the "set PAGE, then read paged register" pattern used by hwmon attributes), so an unlocked debugfs reader can land between a PAGE write and the subsequent paged read in another thread. READ_STATE itself is not paged, so it cannot corrupt PAGE in flight, but the same defensive serialisation that applies to the GPIO accessors applies here: any direct device access from outside pmbus_core should be ordered with respect to pmbus_core's own.

Take pmbus_lock at the top of adm1266_state_read() via the scope-based guard().

---
 drivers/hwmon/pmbus/adm1266.c | 5 +++++
 1 file changed, 5 insertions(+)

index 2c4d94cc87294..3c786c4c1b213 100644
@@ -322,7 +322,12 @@ static int adm1266_state_read(struct seq_file *s, void *pdata)
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;
 
+	ret = pmbus_lock_interruptible(client);
+	if (ret)
+		return ret;
+
 	ret = i2c_smbus_read_word_data(client, ADM1266_READ_STATE);
+	pmbus_unlock(client);
 	if (ret < 0)
 		return ret;
 

2.53.0