FAILED: patch "[PATCH] hwmon: (pmbus/adm1266) serialize sequencer_state debugfs read" failed to apply to 6.18-stable tree

The patch below does not apply to the 6.18-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-6.18.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-ending-creation-bc11@gregkh' --subject-prefix 'PATCH 6.18.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: Guenter Roeck <[email protected]>

[ Upstream commit 1814f4d3ff358277a5b6957e7f133c2812dc80ec ]

Add support for guard(pmbus_lock)() and scoped_guard(pmbus_lock)() to be able to simplify the PMBus code.

Also introduce pmbus_lock() as pre-requisite for supporting guard().

Stable-dep-of: 4e4af55aaca7 ("hwmon: (pmbus/adm1266) serialize sequencer_state debugfs read with pmbus_lock")

---
 drivers/hwmon/pmbus/pmbus.h      | 5 +++++
 drivers/hwmon/pmbus/pmbus_core.c | 8 ++++++++
 2 files changed, 13 insertions(+)

index d2e9bfb5320fc..e499cdae9442c 100644
@@ -10,6 +10,7 @@
 #define PMBUS_H
 
 #include <linux/bitops.h>
+#include <linux/cleanup.h>
 #include <linux/regulator/driver.h>
 
 /*

@@ -563,7 +564,11 @@ int pmbus_get_fan_rate_device(struct i2c_client *client, int page, int id,
 int pmbus_get_fan_rate_cached(struct i2c_client *client, int page, int id,
 			      enum pmbus_fan_mode mode);
 int pmbus_lock_interruptible(struct i2c_client *client);
+void pmbus_lock(struct i2c_client *client);
 void pmbus_unlock(struct i2c_client *client);
+
+DEFINE_GUARD(pmbus_lock, struct i2c_client *, pmbus_lock(_T), pmbus_unlock(_T))
+
 int pmbus_update_fan(struct i2c_client *client, int page, int id,
 		     u8 config, u8 mask, u16 command);
 struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client);

index 572be3ebc03df..7150f12d26300 100644
@@ -3871,6 +3871,14 @@ struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client)
 }
 EXPORT_SYMBOL_NS_GPL(pmbus_get_debugfs_dir, "PMBUS");
 
+void pmbus_lock(struct i2c_client *client)
+{
+	struct pmbus_data *data = i2c_get_clientdata(client);
+
+	mutex_lock(&data->update_lock);
+}
+EXPORT_SYMBOL_NS_GPL(pmbus_lock, "PMBUS");
+
 int pmbus_lock_interruptible(struct i2c_client *client)
 {
 	struct pmbus_data *data = i2c_get_clientdata(client);

2.53.0

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 | 1 +
 1 file changed, 1 insertion(+)

index d90f8f80be8e0..84e01acb0796d 100644
@@ -322,6 +322,7 @@ 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;

2.53.0