On Tue, Jan 22, 2019 at 05:24:54PM +0100, Heiko Carstens wrote:
> On Tue, Jan 22, 2019 at 04:21:02PM +0100, Greg Kroah-Hartman wrote:
> > When calling debugfs functions, there is no need to ever check the
> > return value. The function can work or not, but the code logic should
> > never do something different based on this.
> >
> > Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
> > Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> > Cc: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx>
> > Cc: linux-s390@xxxxxxxxxxxxxxx
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > ---
> > arch/s390/kernel/debug.c | 6 ------
> > arch/s390/kernel/kdebugfs.c | 2 --
> > arch/s390/kernel/sysinfo.c | 2 --
> > 3 files changed, 10 deletions(-)
> > diff --git a/arch/s390/kernel/sysinfo.c b/arch/s390/kernel/sysinfo.c
> > index 12f80d1f0415..2ac3c9b56a13 100644
> > --- a/arch/s390/kernel/sysinfo.c
> > +++ b/arch/s390/kernel/sysinfo.c
> > @@ -545,8 +545,6 @@ static __init int stsi_init_debugfs(void)
> > int lvl, i;
> >
> > stsi_root = debugfs_create_dir("stsi", arch_debugfs_dir);
> > - if (IS_ERR_OR_NULL(stsi_root))
> > - return 0;
>
> No objections, however will you also change the odd behaviour that
> e.g. debugfs_create_file() returns -ENODEV instead of (the expected)
> NULL pointer if CONFIG_DEBUGFS is disabled?
Nope. That is intentional.
> I do remember this since it caused at least one crash ;)
Which is why you shouldn't care about the return value of these
functions :)
> 19cdd08ba155 ("[S390] qdio: fix broken pointer in case of CONFIG_DEBUG_FS is disabled").
Odd, what crashes when passed an error pointer? What was someone trying
to do with those pointers? The only thing you can do with a return
value from a debugfs function is to pass it back into another debugfs
call. Sounds like someone wasn't doing that :(
Given that that patch was from 2.6.29, I think we are safe...
thanks,
greg k-h
