[Mesa-dev] [PATCH] etnaviv: Avoid infinite loop in find_frame()

[Rhys Kidd]

On 20 January 2017 at 17:06, Christian Gmeiner <christian.gmeiner at gmail.com>
wrote:

> Hi Rhys,
>
> 2017-01-19 7:02 GMT+01:00 Rhys Kidd <rhyskidd at gmail.com>:
> > Use of unsigned loop control variable with '>= 0' would lead to infinite
> loop.
> >
> > Reported by clang:
> >
> > etnaviv_compiler.c:1024:39: warning: comparison of unsigned expression
> >= 0 is
> >       always true [-Wtautological-compare]
> >    for (unsigned sp = c->frame_sp; sp >= 0; sp--)
> >                                    ~~ ^  ~
> >
> > Signed-off-by: Rhys Kidd <rhyskidd at gmail.com>
> > ---
> >  src/gallium/drivers/etnaviv/etnaviv_compiler.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > I compile tested etnaviv but have not functionally tested on real
> hardware.
> >
> > diff --git a/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> b/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> > index 59e1452..f1c6787 100644
> > --- a/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> > +++ b/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> > @@ -1021,7 +1021,7 @@ label_mark_use(struct etna_compile *c, struct
> etna_compile_label *label)
> >  static struct etna_compile_frame *
> >  find_frame(struct etna_compile *c, enum etna_compile_frame_type type)
> >  {
> > -   for (unsigned sp = c->frame_sp; sp >= 0; sp--)
> > +   for (unsigned sp = c->frame_sp + 1; sp-- > 0 ; )
>
> looks quite ugly - I have a better and simpler fix.
>
> >        if (c->frame_stack[sp].type == type)
> >           return &c->frame_stack[sp];
> >
> > --
> > 2.9.3
> >
>
> ------------8<-------------------
>
> Subject: [PATCH] etnaviv: Avoid infinite loop in find_frame()
>
> Use of unsigned loop control variable with '>= 0' would lead to infinite
> loop.
>
> Reported by clang:
>
> etnaviv_compiler.c:1024:39: warning: comparison of unsigned expression
> >= 0 is always true [-Wtautological-compare]
>    for (unsigned sp = c->frame_sp; sp >= 0; sp--)
>                                    ~~ ^  ~
>
> v2: Simply use the same datatype as c->frame_sp is using.
>
> Reported-by: Rhys Kidd <rhyskidd at gmail.com>
> Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
> ---
>  src/gallium/drivers/etnaviv/etnaviv_compiler.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> b/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> index 59e1452..dc9af57 100644
> --- a/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> +++ b/src/gallium/drivers/etnaviv/etnaviv_compiler.c
> @@ -1021,7 +1021,7 @@ label_mark_use(struct etna_compile *c, struct
> etna_compile_label *label)
>  static struct etna_compile_frame *
>  find_frame(struct etna_compile *c, enum etna_compile_frame_type type)
>  {
> -   for (unsigned sp = c->frame_sp; sp >= 0; sp--)
> +   for (int sp = c->frame_sp; sp >= 0; sp--)
>        if (c->frame_stack[sp].type == type)
>           return &c->frame_stack[sp];
>
> --
> 2.9.3
> ------------8<-------------------
>
> If you are okay with that I will push it in the next days.
>
>
Reviewed-by: Rhys Kidd <rhyskidd at gmail.com>


> greets
> --
> Christian Gmeiner, MSc
>
> https://www.youtube.com/user/AloryOFFICIAL
> https://soundcloud.com/christian-gmeiner
>
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