Re: [PATCH v3 09/11] powerpc/papr_scm: Return the string length from the sysfs show functions

[Kees Cook]

On Thu, Oct 01, 2026 at 09:47:56AM +0530, Madhavan Srinivasan wrote:
> 
> On 10/1/26 5:22 AM, Kees Cook wrote:
> > perf_stats_show() and flags_show() build their output with a seq_buf
> > and return seq_buf_used(), which may include the trailing NUL byte
> > when the seq_buf has overflowed. Use seq_buf_strlen() instead.
> > 
> > Build tested ARCH=powerpc ppc64_defconfig with GCC powerpc64-linux-gnu
> > 16.1.0:
> > arch/powerpc/platforms/pseries/papr_scm.o
> > 
> > Assisted-by: LLM
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
> > ---
> >   arch/powerpc/platforms/pseries/papr_scm.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> > index 75da96c08cdd..b03cfd8528f5 100644
> > --- a/arch/powerpc/platforms/pseries/papr_scm.c
> > +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> > @@ -1108,7 +1108,7 @@ static ssize_t perf_stats_show(struct device *dev,
> >   free_stats:
> >   	kfree(stats);
> > -	return rc ? rc : (ssize_t)seq_buf_used(&s);
> > +	return rc ?: (ssize_t)seq_buf_strlen(&s);
> >   }
> >   static DEVICE_ATTR_ADMIN_RO(perf_stats);
> > @@ -1150,7 +1150,7 @@ static ssize_t flags_show(struct device *dev,
> >   	if (seq_buf_used(&s))
> 
> this can also be seq_buf_strlen instead

It could be, yeah. I left it because it seemed be more about "did we
touch this at all?" But it's honestly all the same. I will respin with
it changed too.

> 
> >   		seq_buf_printf(&s, "\n");
> > -	return seq_buf_used(&s);
> > +	return seq_buf_strlen(&s);
> >   }
> >   DEVICE_ATTR_RO(flags);

-- 
Kees Cook