From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f172.google.com (mail-dy1-f172.google.com [74.125.82.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E055635E95F for ; Sun, 22 Mar 2026 16:34:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774197254; cv=none; b=fCg8/lczNqmXcHTaBqNqgIiu09sFnLvN9ysz4CDOcmyaeZlIkLHi8o8hKCQc2QCwywVOrEd6W2JLcvCzAC+cUIQ5WVt9+BsnVl8EXqFcUj1gEtzKGyhnkLsjwm6w7c0doFhe5wo9H6ZFpn4qJf0HXM3bmwWZ4O8RGIVfAOXWkRs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774197254; c=relaxed/simple; bh=qNOYVfI3mbuyG8mqvwWtxFBm24Z6R38Th/RXdzXsfuA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=snm8irU3QeBouy7sb6RyDJ01r0JysqkuvGT5xu9mFEeFU5o/GqKHf3Wz+l7YPDFuFkfXGQ5bZaAqvK/9tqFUdRgreBO4M4PhkkWp3WIBWRs2Zt2o8gch96LKoxSy1MPeUdB12c0aWFjjpnDsFndAVNpb21T2DWsOLDPACUXZ/js= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=PhqaOSlk; arc=none smtp.client-ip=74.125.82.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PhqaOSlk" Received: by mail-dy1-f172.google.com with SMTP id 5a478bee46e88-2c1092cc08cso351790eec.1 for ; Sun, 22 Mar 2026 09:34:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1774197252; x=1774802052; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:sender:from:to:cc:subject:date:message-id:reply-to; bh=ZJhZUFgvtgrG9ysLM9vDRCWJf/E4J1jQMl0z9MMFnT4=; b=PhqaOSlkHM+RE+wiRcGmYcKHOI+d8zSSodXcSyitFYa3pDsGkBIgPwLdhlmGGx4+xd Q7aQLEAOFuN6FICWhpNHTaMELE7Lo/juT6soa/v4tEnMt4qczDW7ycu/MglXFh0kJBvX 8Gm/VWW/u0EFNkpJAW0EjjIVEutw4hF03zdT35be2rIBcUKldNdXHgTi4XhZnvrG9q+r JO/5mDMnz3ilTveTI/qUN9L2Xe9/8HaFQ8uZYzcDvyY0OKmTnl3V3FEbpxZBu2j09WUc xNE1gP7akUBil8X0ksF4Cqdp8xCV8yXJlBzdrpw8i17wq0NhPdbK64iKWwnBz3UJzCfx XmBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774197252; x=1774802052; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:sender:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ZJhZUFgvtgrG9ysLM9vDRCWJf/E4J1jQMl0z9MMFnT4=; b=cDPVHcvhAyxuJOGpIISMvazYORCexIDL/Oq+QYrBjYpQp8blBVerzk0DwoygWEdMJ2 hznuQcULwCTUX6NqHxAqj0zATDt4ru+DDNifRjKi/iuNf5K52RdtbBsQILATwrIt4qQG TQl9Su5fHtjWnbRyiIvkIaiy0hfee1kbWP2+ublGXTAchbvxtdALfP6c6HVtQD9Om1Ea UJ4vvZW/Q5pm2uYQLPdETej4DfUcAo8l1c36rXO2qwjFn0HnICacB4vz6f2XrThk/68p IJnrTfAhZfUusOChjKWOdRoTmJJSGqxU5UjQ40VtZpjmyBVHPV+YoG9U6oo9D/g2SQqn CWZw== X-Gm-Message-State: AOJu0YzbhNnUk/DzKROYuRIM7S4jDSfYmX/Xdpoz06n+YZ8ko/fNLMB0 OG7TCwjhRzlwSklh4O2twxaWjVQ6EN9A33ynFSrfHlM5Aj2ocNv0fFnrAdNmqw== X-Gm-Gg: ATEYQzyp/w4OkWyFeGAxVbnKYOVBH4W2Euerkk1F1eNm/22cNggRmVy3WLnm5rbgos2 L8DXaKnQzQmxN4voqB2v4tDIhjw/hdyvy0uzr5+XgNtFX0MBehZcZfpkfBbzHOzws83HNE97ah1 KN1e8zcXsQsGspPVxBNSexSQOgWzX5P7U660cFCKm7GgVlV2l0tyj2+/10mbiAu7nD7ma9fWv9M PTPoNry+e6Hf2mWoazCNmJlhdl8o5aQti2PmtABV14RhQSdxvlZbRVEQUz7mug6g8LX8Vf2dWxG YybDIkfOxo0EAjBa3o0U99ZYB2Ks69WYyj751yZVo/FCgFZv8jzfKR4+xjOY0fPRVpdcJwXvtk1 o56uO8Hp85O64nt7WsbcR2LjP6dBZ2P6wxCDPORqa/b56PReZluY11JbOgiBXk/d9tfyqUdeHrj lVjM5BzEWodm0ylXoWypq+W9W70B3mcDnoT2sg X-Received: by 2002:a05:7300:572a:b0:2be:e4b:60d2 with SMTP id 5a478bee46e88-2c1095a74e0mr4820047eec.4.1774197251549; Sun, 22 Mar 2026 09:34:11 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2c10b2e6c30sm9962808eec.25.2026.03.22.09.34.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Mar 2026 09:34:11 -0700 (PDT) Sender: Guenter Roeck From: Guenter Roeck To: Hardware Monitoring Cc: Guenter Roeck , Sanman Pradhan Subject: [RFT PATCH] hwmon: (pmbus/core) Protect regulator operations with mutex Date: Sun, 22 Mar 2026 09:34:06 -0700 Message-ID: <20260322163406.1530478-1-linux@roeck-us.net> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The regulator operations pmbus_regulator_get_voltage(), pmbus_regulator_set_voltage(), and pmbus_regulator_list_voltage() access PMBus registers and shared data but were not protected by the update_lock mutex. This could lead to race conditions. However, adding mutex protection directly to these functions causes a deadlock because pmbus_regulator_notify() (which calls regulator_notifier_call_chain()) is often called with the mutex already held (e.g., from pmbus_fault_handler()). If a regulator callback then calls one of the now-protected voltage functions, it will attempt to acquire the same mutex. Rework pmbus_regulator_notify() to utilize a worker function to send notifications outside of the mutex protection. Events are stored as atomics in a per-page bitmask and processed by the worker. Initialize the worker and its associated data during regulator registration, and ensure it is cancelled on device removal using devm_add_action_or_reset(). While at it, remove the unnecessary include of linux/of.h. Cc: Sanman Pradhan Signed-off-by: Guenter Roeck --- drivers/hwmon/pmbus/pmbus_core.c | 114 ++++++++++++++++++++++++------- 1 file changed, 89 insertions(+), 25 deletions(-) diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c index be6d05def115..c349ffd6ea21 100644 --- a/drivers/hwmon/pmbus/pmbus_core.c +++ b/drivers/hwmon/pmbus/pmbus_core.c @@ -6,6 +6,7 @@ * Copyright (c) 2012 Guenter Roeck */ +#include #include #include #include @@ -21,8 +22,8 @@ #include #include #include -#include #include +#include #include "pmbus.h" /* @@ -112,6 +113,11 @@ struct pmbus_data { struct mutex update_lock; +#if IS_ENABLED(CONFIG_REGULATOR) + atomic_t regulator_events[PMBUS_PAGES]; + struct work_struct regulator_notify_work; +#endif + bool has_status_word; /* device uses STATUS_WORD register */ int (*read_status)(struct i2c_client *client, int page); @@ -3176,12 +3182,19 @@ static int pmbus_regulator_get_voltage(struct regulator_dev *rdev) .class = PSC_VOLTAGE_OUT, .convert = true, }; + int ret; + mutex_lock(&data->update_lock); s.data = _pmbus_read_word_data(client, s.page, 0xff, PMBUS_READ_VOUT); - if (s.data < 0) - return s.data; + if (s.data < 0) { + ret = s.data; + goto unlock; + } - return (int)pmbus_reg2data(data, &s) * 1000; /* unit is uV */ + ret = (int)pmbus_reg2data(data, &s) * 1000; /* unit is uV */ +unlock: + mutex_unlock(&data->update_lock); + return ret; } static int pmbus_regulator_set_voltage(struct regulator_dev *rdev, int min_uv, @@ -3198,16 +3211,22 @@ static int pmbus_regulator_set_voltage(struct regulator_dev *rdev, int min_uv, }; int val = DIV_ROUND_CLOSEST(min_uv, 1000); /* convert to mV */ int low, high; + int ret; *selector = 0; + mutex_lock(&data->update_lock); low = pmbus_regulator_get_low_margin(client, s.page); - if (low < 0) - return low; + if (low < 0) { + ret = low; + goto unlock; + } high = pmbus_regulator_get_high_margin(client, s.page); - if (high < 0) - return high; + if (high < 0) { + ret = high; + goto unlock; + } /* Make sure we are within margins */ if (low > val) @@ -3217,7 +3236,10 @@ static int pmbus_regulator_set_voltage(struct regulator_dev *rdev, int min_uv, val = pmbus_data2reg(data, &s, val); - return _pmbus_write_word_data(client, s.page, PMBUS_VOUT_COMMAND, (u16)val); + ret = _pmbus_write_word_data(client, s.page, PMBUS_VOUT_COMMAND, (u16)val); +unlock: + mutex_unlock(&data->update_lock); + return ret; } static int pmbus_regulator_list_voltage(struct regulator_dev *rdev, @@ -3227,6 +3249,7 @@ static int pmbus_regulator_list_voltage(struct regulator_dev *rdev, struct i2c_client *client = to_i2c_client(dev->parent); struct pmbus_data *data = i2c_get_clientdata(client); int val, low, high; + int ret; if (data->flags & PMBUS_VOUT_PROTECTED) return 0; @@ -3239,18 +3262,29 @@ static int pmbus_regulator_list_voltage(struct regulator_dev *rdev, val = DIV_ROUND_CLOSEST(rdev->desc->min_uV + (rdev->desc->uV_step * selector), 1000); /* convert to mV */ + mutex_lock(&data->update_lock); + low = pmbus_regulator_get_low_margin(client, rdev_get_id(rdev)); - if (low < 0) - return low; + if (low < 0) { + ret = low; + goto unlock; + } high = pmbus_regulator_get_high_margin(client, rdev_get_id(rdev)); - if (high < 0) - return high; + if (high < 0) { + ret = high; + goto unlock; + } - if (val >= low && val <= high) - return val * 1000; /* unit is uV */ + if (val >= low && val <= high) { + ret = val * 1000; /* unit is uV */ + goto unlock; + } - return 0; + ret = 0; +unlock: + mutex_unlock(&data->update_lock); + return ret; } const struct regulator_ops pmbus_regulator_ops = { @@ -3281,12 +3315,19 @@ int pmbus_regulator_init_cb(struct regulator_dev *rdev, } EXPORT_SYMBOL_NS_GPL(pmbus_regulator_init_cb, "PMBUS"); +static void pmbus_regulator_notify_work_cancel(void *data) +{ + struct pmbus_data *pdata = data; + + cancel_work_sync(&pdata->regulator_notify_work); +} + static int pmbus_regulator_register(struct pmbus_data *data) { struct device *dev = data->dev; const struct pmbus_driver_info *info = data->info; const struct pmbus_platform_data *pdata = dev_get_platdata(dev); - int i; + int i, ret; data->rdevs = devm_kzalloc(dev, sizeof(struct regulator_dev *) * info->num_regulators, GFP_KERNEL); @@ -3310,19 +3351,42 @@ static int pmbus_regulator_register(struct pmbus_data *data) info->reg_desc[i].name); } + INIT_WORK(&data->regulator_notify_work, pmbus_regulator_notify_worker); + + ret = devm_add_action_or_reset(dev, pmbus_regulator_notify_work_cancel, data); + if (ret) + return ret; + return 0; } +static void pmbus_regulator_notify_worker(struct work_struct *work) +{ + struct pmbus_data *data = + container_of(work, struct pmbus_data, regulator_notify_work); + int i, j; + + for (i = 0; i < data->info->pages; i++) { + int event; + + event = atomic_xchg(&data->regulator_events[i], 0); + if (!event) + continue; + + for (j = 0; j < data->info->num_regulators; j++) { + if (i == rdev_get_id(data->rdevs[j])) { + regulator_notifier_call_chain(data->rdevs[j], + event, NULL); + break; + } + } + } +} + static void pmbus_regulator_notify(struct pmbus_data *data, int page, int event) { - int j; - - for (j = 0; j < data->info->num_regulators; j++) { - if (page == rdev_get_id(data->rdevs[j])) { - regulator_notifier_call_chain(data->rdevs[j], event, NULL); - break; - } - } + atomic_or(event, &data->regulator_events[page]); + schedule_work(&data->regulator_notify_work); } #else static int pmbus_regulator_register(struct pmbus_data *data) -- 2.45.2