Messages in this thread | | | Date | Thu, 19 Sep 2019 14:53:00 -0700 | From | Bjorn Andersson <> | Subject | Re: [PATCH] base: soc: Export soc_device_to_device API |
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On Thu 19 Sep 14:32 PDT 2019, Greg KH wrote:
> On Thu, Sep 19, 2019 at 02:13:44PM -0700, Murali Nalajala wrote: > > If the soc drivers want to add custom sysfs entries it needs to > > access "dev" field in "struct soc_device". This can be achieved > > by "soc_device_to_device" API. Soc drivers which are built as a > > module they need above API to be exported. Otherwise one can > > observe compilation issues. > > > > Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org> > > --- > > drivers/base/soc.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/base/soc.c b/drivers/base/soc.c > > index 7c0c5ca..4ad52f6 100644 > > --- a/drivers/base/soc.c > > +++ b/drivers/base/soc.c > > @@ -41,6 +41,7 @@ struct device *soc_device_to_device(struct soc_device *soc_dev) > > { > > return &soc_dev->dev; > > } > > +EXPORT_SYMBOL_GPL(soc_device_to_device); > > > > static umode_t soc_attribute_mode(struct kobject *kobj, > > struct attribute *attr, > > What in-kernel driver needs this? >
Half of the drivers interacting with the soc driver calls this API, several of these I see no reason for being builtin (e.g. ux500 andversatile). So I think this patch makes sense to allow us to build these as modules.
> Is linux-next breaking without this? >
No, we postponed the addition of any sysfs attributes in the Qualcomm socinfo driver.
> We don't export things unless we have a user of the export. > > Also, adding "custom" sysfs attributes is almost always not the correct > thing to do at all. The driver should be doing it, by setting up the > attribute group properly so that the driver core can do it automatically > for it. > > No driver should be doing individual add/remove of sysfs files. If it > does so, it is almost guaranteed to be doing it incorrectly and racing > userspace. >
The problem here is that the attributes are expected to be attached to the soc driver, which is separate from the platform-specific drivers. So there's no way to do platform specific attributes the right way.
> And yes, there's loads of in-kernel examples of doing this wrong, I've > been working on fixing that up, look at the patches now in Linus's tree > for platform and USB drivers that do this as examples of how to do it > right. >
Agreed, this patch should not be used as an approval for any crazy attributes; but it's necessary in order to extend the soc device's attributes, per the current design.
So:
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Regards, Bjorn
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