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

[Christian Gmeiner]

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.

greets
--
Christian Gmeiner, MSc

https://www.youtube.com/user/AloryOFFICIAL
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