On Mon, Jan 30, 2023 at 12:14:04PM +0200, Mike Rapoport wrote: > Hi, > > On Fri, Jan 27, 2023 at 08:58:44PM +0900, Hyunmin Lee wrote: > > Replace unnacessary BUG_ON to WARN_ON. These BUG_ONs verify aruguments of a function. Thus, the WARN_ONs return an EINVAL error when their condition is true. > > Some users enable panic_on_warn, so for them WARN_ON will still crash a > machine. > > I think a simple if() will be sufficient. > > > Co-Developed-by: Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx> > > Co-Developed-by: Jeungwoo Yoo <casionwoo@xxxxxxxxx> > > Co-Developed-by: Sangyun Kim <sangyun.kim@xxxxxxxxx> > > Signed-off-by: Hyunmin Lee <hn.min.lee@xxxxxxxxx> > > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx> > > Signed-off-by: Jeungwoo Yoo <casionwoo@xxxxxxxxx> > > Signed-off-by: Sangyun Kim <sangyun.kim@xxxxxxxxx> > > Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> > > --- > > mm/vmalloc.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 74afa2208558..9f9dba3132c5 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -1587,9 +1587,14 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, > > int purged = 0; > > int ret; > > > > - BUG_ON(!size); > > - BUG_ON(offset_in_page(size)); > > - BUG_ON(!is_power_of_2(align)); > > + if (WARN_ON(!size)) > > + return ERR_PTR(-EINVAL); > > + > > + if (WARN_ON(offset_in_page(size))) > > + return ERR_PTR(-EINVAL); > > + > > + if (WARN_ON(!is_power_of_2(align))) > > + return ERR_PTR(-EINVAL); > > > > if (unlikely(!vmap_initialized)) > > return ERR_PTR(-EBUSY); > > -- > > 2.25.1 > > > > > > -- > Sincerely yours, > Mike. Hi Mike, Thank you for your advice. Would you please give feedback about the below opinion? - Printing warning messages is helpful to inform what happened in the system to the users. - When a simple if() is used instead of WARN_ON, the if() should print a warning message. - The condition of the simple if() should also have unlikely() for optimization of system performance. - WARN_ON is a macro doing like thoes easily. It has a notifying function and unlikely optimization. - Eventhough WARN_ON will still crash like BUG_ON by some users who enable panic_on_warn, it is their intention. They should accept the crash by WARN_ON. - Therefore, using WARN_ON looks like natural and efficient. Best, Hyunmin
