[PATCH] clkdev: report over-sized strings when creating clkdev entries

[Stephen Boyd]

Quoting Russell King (Oracle) (2024-05-02 04:08:38)
> On Thu, May 02, 2024 at 09:22:39AM +0100, Russell King (Oracle) wrote:
> > On Thu, May 02, 2024 at 09:02:16AM +0100, Russell King (Oracle) wrote:
> > > On Wed, May 01, 2024 at 06:02:54PM -0700, Stephen Boyd wrote:
> > > > Quoting Stephen Boyd (2024-05-01 17:59:16)
> > > > > Quoting Russell King (Oracle) (2024-03-15 04:47:55)
> > > > > > Report an error when an attempt to register a clkdev entry results in a
> > > > > > truncated string so the problem can be easily spotted.
> > > > > > 
> > > > > > Reported by: Duanqiang Wen <duanqiangwen at net-swift.com>
> > > > > > Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> > > > > > ---
> > > > > 
> > > > > Applied to clk-next
> > > > > 
> > > > 
> > > > And backed out because I get a compilation failure
> > > > 
> > > > drivers/clk/clkdev.c: In function 'vclkdev_alloc':
> > > > drivers/clk/clkdev.c:182:17: error: function 'vclkdev_alloc' might be a candidate for 'gnu_printf' format attribute [-Werror=suggest-attribute=format]
> > > >   182 |                 res = vsnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
> > > >       |                 ^~~
> > > > cc1: all warnings being treated as errors
> > > > make[5]: *** [scripts/Makefile.build:244: drivers/clk/clkdev.o] Error 1
> > > > make[4]: *** [scripts/Makefile.build:485: drivers/clk] Error 2
> > > 
> > > It builds fine for me. I don't get this _error_, and it's really no
> > > different from what it originally was - instead of using vcsnprintf()
> > > we're now using vsnprintf(). That should make no difference what so
> > > ever.
> > 
> > ... and I've just checked, and it builds entirely cleanly for me.
> > 
> > I'll merge it.
> 
> It should be in tonight's linux-next tree.

Ok thanks

> 
> I also note... the kernel build bot never flagged the above, not even
> a warning for it, and it would've built the patch as it was Cc'd to
> linux-kernel.

Indeed. I see a report here[1] but it's only a warning. And there was
some work a few years ago[2] that I forgot about. Seems there was a
possible fix[3] as well.

> So my conclusion is the error you are seeing is somehow
> specific to your environment. Maybe you're building with an additional
> set of warning flags and -Werror?
> 

Yes I build with W=1 but I didn't think that turned warnings into
errors. Maybe that part is new.

[1] https://lore.kernel.org/all/202403110643.27JXEVCI-lkp@intel.com/
[2] https://lore.kernel.org/all/20210310085937.GF4931@dell/
[3] https://lore.kernel.org/all/20221111071809.3440-1-liubo03@inspur.com/