From bab8c6fb5af8df7e753d196c1262cb78e92ca872 Mon Sep 17 00:00:00 2001 From: Abdurrahman Hussain Date: Mon, 18 May 2026 17:52:30 -0700 Subject: [PATCH] hwmon: (pmbus/adm1266) serialize GPIO PMBus accesses with pmbus_lock adm1266_gpio_get(), adm1266_gpio_get_multiple(), and adm1266_gpio_dbg_show() all issue PMBus reads against the device but none of them take pmbus_lock. The pmbus_core framework 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 GPIO accessor can land between a PAGE write and the subsequent paged read in another thread and corrupt either side's view of the device state machine. Take pmbus_lock at the top of each of the three accessors via the scope-based guard(). The lock is uncontended in the common case and adds only a single mutex round-trip per call. Fixes: d98dfad35c38 ("hwmon: (pmbus/adm1266) Add support for GPIOs") Cc: stable@vger.kernel.org Signed-off-by: Abdurrahman Hussain Reviewed-by: Bartosz Golaszewski Link: https://lore.kernel.org/r/20260518-adm1266-gpio-fixes-v3-6-e425e4f88139@nexthop.ai Signed-off-by: Guenter Roeck --- drivers/hwmon/pmbus/adm1266.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c index 3e8f2619cb9b..0eef58dd69a6 100644 --- a/drivers/hwmon/pmbus/adm1266.c +++ b/drivers/hwmon/pmbus/adm1266.c @@ -173,6 +173,8 @@ static int adm1266_gpio_get(struct gpio_chip *chip, unsigned int offset) else pmbus_cmd = ADM1266_PDIO_STATUS; + guard(pmbus_lock)(data->client); + ret = i2c_smbus_read_block_data(data->client, pmbus_cmd, read_buf); if (ret < 0) return ret; @@ -195,6 +197,8 @@ static int adm1266_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask unsigned int gpio_nr; int ret; + guard(pmbus_lock)(data->client); + ret = i2c_smbus_read_block_data(data->client, ADM1266_GPIO_STATUS, read_buf); if (ret < 0) return ret; @@ -236,6 +240,8 @@ static void adm1266_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip) int ret; int i; + guard(pmbus_lock)(data->client); + for (i = 0; i < ADM1266_GPIO_NR; i++) { write_cmd = adm1266_gpio_mapping[i][1]; ret = adm1266_pmbus_block_xfer(data, ADM1266_GPIO_CONFIG, 1, &write_cmd, read_buf);