From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DC6FC1C5F0C; Wed, 11 Dec 2024 07:41:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733902912; cv=none; b=G2dAuH0H48rLAzY4l7NqokVWdNfwQesE1+ULQ+ePWjpvszkf2qeKWkzU0ry/O/X81hjYrvDlHhCPaRxqc/xgbJNzzAzMolE2yPngkMjii+HCoziLbkgjL3EKg7IKTmUqju+ipNklxL5HqAFB8GE8iILDxZ+/n/sCG0wJwGQ008A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733902912; c=relaxed/simple; bh=xXbfIkQs4FpPZZWOQhPiNikznCbdkVjiqu8L1MMHCk8=; h=Message-ID:Date:MIME-Version:Subject:From:To:CC:References: In-Reply-To:Content-Type; b=IXrW1Z0XjiFdz4h3kctoGo2wWcBxs/3wMYtFNA32rZEr2/WpyW8g+BrMgvx1oXwalDuQA34rAImJVGRkLDCrdY68H6v4S2CPVnMtURHRH0NIy4KeCj4rDO16GjVSeqYFP0Bhn3jNWDGm8FBD1wP9EoAqjDdJPHh3tbKDMUqfl2Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Y7SCK0k3XzHx08; Wed, 11 Dec 2024 15:38:53 +0800 (CST) Received: from dggemv704-chm.china.huawei.com (unknown [10.3.19.47]) by mail.maildlp.com (Postfix) with ESMTPS id 296F21802D0; Wed, 11 Dec 2024 15:41:46 +0800 (CST) Received: from kwepemn100009.china.huawei.com (7.202.194.112) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Wed, 11 Dec 2024 15:41:45 +0800 Received: from [10.67.121.59] (10.67.121.59) by kwepemn100009.china.huawei.com (7.202.194.112) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 11 Dec 2024 15:41:45 +0800 Message-ID: <4499f49f-e846-66c6-3017-deb5bc63c31f@huawei.com> Date: Wed, 11 Dec 2024 15:41:44 +0800 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v1 1/4] hwmon: (acpi_power_meter) Fix using uninitialized variables From: "lihuisong (C)" To: Guenter Roeck CC: , , , , , References: <20241125093415.21719-1-lihuisong@huawei.com> <20241125093415.21719-2-lihuisong@huawei.com> <77fce1aa-96eb-4c3c-ab0a-a33de46b333b@roeck-us.net> <87367d88-b10e-29d6-2712-f8f5c24e52a4@huawei.com> In-Reply-To: <87367d88-b10e-29d6-2712-f8f5c24e52a4@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemn100009.china.huawei.com (7.202.194.112) Hi Guenter, Can you take a look at my following reply? Looking forward to your reply. /Huisong 在 2024/11/27 11:43, lihuisong (C) 写道: > Hi Guenter， > > How about the modification as below? But driver doesn't know what the > time is to set resource->power_alarm to false. > > 在 2024/11/27 0:19, Guenter Roeck 写道: >> On 11/25/24 23:03, lihuisong (C) wrote: >>> >>> 在 2024/11/26 12:04, Guenter Roeck 写道: >>>> On 11/25/24 17:56, lihuisong (C) wrote: >>>>> Hi Guente, >>>>> >>>>> Thanks for your timely review. >>>>> >>>>> 在 2024/11/26 0:03, Guenter Roeck 写道: >>>>>> On 11/25/24 01:34, Huisong Li wrote: >>>>>>> The 'power1_alarm' attribute uses the 'power' and 'cap' in the >>>>>>> acpi_power_meter_resource structure. However, these two fields >>>>>>> are just >>>>>>> updated when user query 'power' and 'cap' attribute, or hardware >>>>>>> enforced >>>>>>> limit. If user directly query the 'power1_alarm' attribute >>>>>>> without queryng >>>>>>> above two attributes, driver will use the uninitialized >>>>>>> variables to judge. >>>>>>> In addition, the 'power1_alarm' attribute needs to update power >>>>>>> and cap to >>>>>>> show the real state. >>>>>>> >>>>>>> Signed-off-by: Huisong Li >>>>>>> --- >>>>>>>   drivers/hwmon/acpi_power_meter.c | 10 ++++++++++ >>>>>>>   1 file changed, 10 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/hwmon/acpi_power_meter.c >>>>>>> b/drivers/hwmon/acpi_power_meter.c >>>>>>> index 2f1c9d97ad21..4c3314e35d30 100644 >>>>>>> --- a/drivers/hwmon/acpi_power_meter.c >>>>>>> +++ b/drivers/hwmon/acpi_power_meter.c >>>>>>> @@ -396,6 +396,9 @@ static ssize_t show_val(struct device *dev, >>>>>>>       struct acpi_device *acpi_dev = to_acpi_device(dev); >>>>>>>       struct acpi_power_meter_resource *resource = >>>>>>> acpi_dev->driver_data; >>>>>>>       u64 val = 0; >>>>>>> +    int ret; >>>>>>> + >>>>>>> +    guard(mutex)(&resource->lock); >>>>>>>         switch (attr->index) { >>>>>>>       case 0: >>>>>>> @@ -423,6 +426,13 @@ static ssize_t show_val(struct device *dev, >>>>>>>               val = 0; >>>>>>>           break; >>>>>>>       case 6: >>>>>>> +        ret = update_meter(resource); >>>>>>> +        if (ret) >>>>>>> +            return ret; >>>>>>> +        ret = update_cap(resource); >>>>>>> +        if (ret) >>>>>>> +            return ret; >>>>>>> + >>>>>>>           if (resource->power > resource->cap) >>>>>>>               val = 1; >>>>>>>           else >>>>>> >>>>>> >>>>>> While technically correct, the implementation of this attribute >>>>>> defeats its >>>>>> purpose. It is supposed to reflect the current status as reported >>>>>> by the >>>>>> hardware. A real fix would be to use the associated notification >>>>>> to set or >>>>>> reset a status flag, and to report the current value of that flag >>>>>> as reported >>>>>> by the hardware. >>>>> I know what you mean. >>>>> The Notify(power_meter, 0x83) is supposed to meet your proposal IIUC. >>>>> It's good, but it depands on hardware support notification. >>>>>> >>>>>> If there is no notification support, the attribute should not >>>>>> even exist, >>>>>> unless there is a means to retrieve its value from ACPI (the >>>>>> status itself, >>>>>> not by comparing temperature values). >>>>> Currently, the 'power1_alarm' attribute is created just when >>>>> platform support the power meter meassurement(bit0 of the >>>>> supported capabilities in _PMC). >>>>> And it doesn't see if the platform support notifications. >>>>>  From the current implementation of this driver, this sysfs can >>>>> also reflect the status by comparing power and cap, >>>>> which is good to the platform that support hardware limit from >>>>> some out-of-band mechanism but doesn't support any notification. >>>>> >>>> >>>> The point is that this can also be done from userspace. Hardware >>>> monitoring drivers >>>> are supposed to provide hardware attributes, not software >>>> attributes derived from it. >>>> >>> So this 'power1_alarm' attribute can be exposed when platform >>> supports hardware enforced limit and notifcations when the hardware >>> limit is enforced, right? >>> If so, we have to change the condition that driver creates this >>> sysfs interface. >> >> This isn't about enforcing anything, it is about reporting an alarm >> if the power consumed exceeds the maximum configured. >> > --> > > index 2f1c9d97ad21..b436ebd863e6 > --- a/drivers/hwmon/acpi_power_meter.c > +++ b/drivers/hwmon/acpi_power_meter.c > @@ -84,6 +84,7 @@ struct acpi_power_meter_resource { >         u64             power; >         u64             cap; >         u64             avg_interval; > +       bool            power_alarm; >         int                     sensors_valid; >         unsigned long           sensors_last_updated; >         struct sensor_device_attribute  sensors[NUM_SENSORS]; > @@ -396,6 +397,9 @@ static ssize_t show_val(struct device *dev, >         struct acpi_device *acpi_dev = to_acpi_device(dev); >         struct acpi_power_meter_resource *resource = > acpi_dev->driver_data; >         u64 val = 0; > +       int ret; > + > +       guard(mutex)(&resource->lock); > >         switch (attr->index) { >         case 0: > @@ -423,10 +427,21 @@ static ssize_t show_val(struct device *dev, >                         val = 0; >                 break; >         case 6: > -               if (resource->power > resource->cap) > -                       val = 1; > -               else > -                       val = 0; > +               /* report alarm status based on the notification if > support. */ > +               if (resource->caps.flags & POWER_METER_CAN_NOTIFY) { > +                       val = resource->power_alarm; > +               } else { > +                       ret = update_meter(resource); > +                       if (ret) > +                               return ret; > +                       ret = update_cap(resource); > +                       if (ret) > +                               return ret; > +                       if (resource->power > resource->cap) > +                               val = 1; > +                       else > +                               val = 0; > +               } >                 break; >         case 7: >         case 8: > @@ -853,6 +868,7 @@ static void acpi_power_meter_notify(struct > acpi_device *device, u32 event) >                 sysfs_notify(&device->dev.kobj, NULL, > POWER_AVG_INTERVAL_NAME); >                 break; >         case METER_NOTIFY_CAPPING: > +               resource->power_alarm = true; >                 sysfs_notify(&device->dev.kobj, NULL, POWER_ALARM_NAME); >                 dev_info(&device->dev, "Capping in progress.\n"); >                 break; > >> . > > .