Messages in this thread | | | Subject | Re: userspace regression with hwmon | From | Guenter Roeck <> | Date | Tue, 27 Jun 2017 05:52:39 -0700 |
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On 06/27/2017 05:23 AM, Sudip Mukherjee wrote: > On Mon, Jun 26, 2017 at 10:06:11AM -0700, Guenter Roeck wrote: >> On Mon, Jun 26, 2017 at 03:33:20PM +0100, Sudip Mukherjee wrote: >>> Hi Guenter, Jean, >>> >>> The patch d72d19c26c41 ("hwmon: (coretemp) Convert to use >>> devm_hwmon_device_register_with_groups") has changed the location of the >>> sysfs nodes from /sys/devices/platform/coretemp.0/ to >>> /sys/devices/platform/coretemp.0/hwmon/hwmon0/ and that has broken >>> some of our usespace applications when we have updated the kernel from >>> v3.8 to v4.4. For now I am reverting that said patch in our production >>> kernel (based on v4.4) but that is not an elegant solution. >>> Do you have any other reports like this? I am sure changing the paths >>> upstream will now break some other userspace. So, what can be an elegant >>> solution to our problem? or do we always need to carry an out-of-tree >>> patch for our production kernel? >>> >> >> The problem only occurs if attributes are accessed using the raw path, >> and if user space does not take into account that attributes may reside >> in the hwmon directory (/sys/class/hwmon/hwmonX) _or_ in the device >> directory (/sys/class/hwmon/hwmonX/device). There is no guarantee that >> the raw path doesn't change from release to release; that is what the >> symlinks are for. Actually, I have seen the raw platform device path >> change over time, so I am surprised that this never affected you. > > Well, using the raw platform device path was a bad design decision. > But I still see a difference. In v3.8 all the temp* nodes were in > /sys/class/hwmon/hwmon0/device/ but in v4.4 I can see that they are in > /sys/class/hwmon/hwmon0/. So if we do modify the code, then we still > need to have two versions of userspace code based on the kernel. >
Your code should check for the 'name' attribute in both locations.
Guenter
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