[PATCH] drm/amd/powerplay: ensure loop does not wraparound on decrement
walter harms
wharms at bfs.de
Thu May 18 07:15:51 UTC 2017
Am 17.05.2017 20:13, schrieb Colin King:
> From: Colin Ian King <colin.king at canonical.com>
>
> The current for loop decrements i when it is zero and this causes
> a wrap-around back to ~0 because i is unsigned. In the unlikely event
> that mask is 0, the loop will run forever. Fix this so we can't loop
> forever.
>
> Detected by CoverityScan, CID#1435469 ("Unsigned compared against 0")
>
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
> drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c
> index ad30f5d3a10d..d92c9b9b15be 100644
> --- a/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c
> +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c
> @@ -4199,7 +4199,7 @@ static int vega10_force_clock_level(struct pp_hwmgr *hwmgr,
> }
> data->smc_state_table.gfx_boot_level = i;
>
> - for (i = 31; i >= 0; i--) {
> + for (i = 32; --i; ) {
> if (mask & (1 << i))
> break;
> }
nitpicking:
we notices at several points that programmers are bad at counting backwards.
Is there a reason not to start with i=0 ?
re,
wh
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