Messages in this thread | | | Date | Tue, 15 May 2018 10:16:02 +0200 | From | Jean Delvare <> | Subject | Re: [PATCH v2] i2c: i801: fix unused-function warning |
| |
Hi Andy,
On Mon, 14 May 2018 20:18:37 +0300, Andy Shevchenko wrote: > On Mon, May 14, 2018 at 12:33 PM, Anders Roxell > <anders.roxell@linaro.org> wrote: > > With CONFIG_PM, we get a harmless build warning: > > drivers/i2c/busses/i2c-i801.c:1723:12: warning: ‘i801_resume’ defined but not used [-Wunused-function] > > static int i801_resume(struct device *dev) > > ^~~~~~~~~~~ > > drivers/i2c/busses/i2c-i801.c:1714:12: warning: ‘i801_suspend’ defined but not used [-Wunused-function] > > static int i801_suspend(struct device *dev) > > ^~~~~~~~~~~~ > > > -#ifdef CONFIG_PM > > +#ifdef CONFIG_PM_SLEEP > > static int i801_suspend(struct device *dev) > > The better pattern is to get rid of ugly ifdef and supply > __maybe_unused annotation to each function in question.
That was Anders' first proposal, but it was declined by the driver maintainer (me.) See:
https://marc.info/?l=linux-kernel&m=152588526520326&w=2
__maybe_unused is just a way to prevent the compiler from doing its job. If it's really what you want, you might as well build with -Wno-unused, instead of crippling the code with yet another annotation.
I can't see how building unused code only to discard it later can be better than a proper #ifdef which will only build the code when we actually need it.
Maybe there are cases where __maybe_unused is actually needed, but in my opinion that should be the last resort option. That's not the case here.
-- Jean Delvare SUSE L3 Support
| |