Re: [PULL v2] First set of iio new device support etc for the 5.5 cycle

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, Oct 12, 2019 at 09:41:45PM +0300, Alexandru Ardelean wrote:
> On Sat, Oct 12, 2019 at 7:18 PM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Sat, 12 Oct 2019 17:28:41 +0200
> > Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > > On Sat, Oct 12, 2019 at 05:27:44PM +0200, Greg KH wrote:
> > > > On Sat, Oct 12, 2019 at 12:19:46PM +0100, Jonathan Cameron wrote:
> > > > > The following changes since commit b73b93a2af3392b9b7b8ba7e818ee767499f9655:
> > > > >
> > > > >   iio: adc: ad7192: Add sysfs ABI documentation (2019-09-08 10:34:49 +0100)
> > > > >
> > > > > are available in the Git repository at:
> > > > >
> > > > >   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git tags/iio-for-5.5a-take2
> > > >
> > > > Better, but I see this now:
> > > >
> > > > drivers/iio/imu/adis.c: In function ‘__adis_check_status’:
> > > > drivers/iio/imu/adis.c:295:9: warning: ‘status’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> > > >   295 |  status &= adis->data->status_error_mask;
> > > >       |         ^~
> > > >
> > > >
> > > > I'll take this, can you just send a follow-on patch for this?
> > >
> > > Also I see:
> > >
> > > drivers/iio/imu/adis16480.c: In function ‘adis16480_enable_irq’:
> > > drivers/iio/imu/adis16480.c:950:6: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> > >   950 |  val &= ~ADIS16480_DRDY_EN_MSK;
> > >       |      ^~
> > >   CC [M]  drivers/iio/magnetometer/hmc5843_i2c.o
> > > drivers/iio/imu/adis16480.c: In function ‘adis16480_write_raw’:
> > > drivers/iio/imu/adis16480.c:571:7: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> > >   571 |   val &= ~enable_mask;
> > >       |       ^~
> > > drivers/iio/imu/adis16480.c:557:11: note: ‘val’ was declared here
> > >   557 |  uint16_t val;
> > >       |           ^~~
> > >
> > >
> > > So did you really fix anything here?
> > >
> > > I'll drop this pull again.
> > >
> > > What version of gcc are you using?  Might I suggest a newer one (i.e. a
> > > modern one?)
> >
> > Ah. This is my mistake.  I did see all of these, but still thought we were
> > in the category of tidying up some compiler version caused issues.
> >
> > The adis16400 came up in my local tests, so I previously pinged Alex on
> > basis it was something to do in a follow up. The other two showed up, but
> > again I still thought these were compiler version issues, particularly
> > as 0-day didn't highlight them (there were several other issues it
> > did highlight this week). Hence again I requested a follow up to tidy
> > it up.
> >
> > Anyhow, did some digging.  The issue here was a 'fix' I put in to an initial
> > 0-day issue in the inline functions that Alex added.  Note that one
> > appears to be compiler version dependent as it didn't turn up in my
> > local builds. There are now inline functions that check if (ret)
> > and don't set the value if ret is non 0.

Oddly, 0-day is not always seeing stuff like this, and I don't know why.

> > Out in the drivers, the check is the more specific (unnecessarily)
> > if (ret < 0) and hence the compiler is concluded that there might be a path to
> > val not being set.  Previously it was giving up figuring this out.
> > So reality is they are a false positive (sort of as in reality ret
> > is never positive) but the compiler has made a reasonable point
> > that it can't see that.
> >
> > Never mind, I'll do a new pull request once fixes are in place.
> > Given there are two obvious ways of suppressing this and it's Alex's
> > driver I'll wait until he has time to take a look.
> >
> > Sorry for wasting your time.
> >
> 
> If it helps, let's drop the ADIS patches for this round, and I can
> take a closer look as well.
> The cleanup does seem to have revealed a few gaps in our CI in
> relation to upstreaming things.
> 
> We use Travis-CI for our stuff and stuff is public:
> https://travis-ci.org/analogdevicesinc/linux
> 
> So, if anyone sees anything we should do better, I'm open to
> improvements/suggestions.

Building 'allmodconfig' with a recent version of gcc?  That's all I did
here to catch these warnings, nothing special :)

thanks,

greg k-h