lkml.org 
[lkml]   [2023]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 4/8] drm/msm/dpu: Disallow unallocated resources to be returned
From
On 09/01/2023 01:28, Dmitry Baryshkov wrote:
> On 22/12/2022 01:19, Marijn Suijten wrote:
>> In the event that the topology requests resources that have not been
>> created by the system (because they are typically not represented in
>> dpu_mdss_cfg ^1), the resource(s) in global_state (in this case DSC
>> blocks) remain NULL but will still be returned out of
>> dpu_rm_get_assigned_resources, where the caller expects to get an array
>> containing num_blks valid pointers (but instead gets these NULLs).
>>
>> To prevent this from happening, where null-pointer dereferences
>> typically result in a hard-to-debug platform lockup, num_blks shouldn't
>> increase past NULL blocks and will print an error and break instead.
>> After all, max_blks represents the static size of the maximum number of
>> blocks whereas the actual amount varies per platform.
>>
>> ^1: which can happen after a git rebase ended up moving additions to
>> _dpu_cfg to a different struct which has the same patch context.
>>
>> Fixes: bb00a452d6f7 ("drm/msm/dpu: Refactor resource manager")
>> Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>
> I think the patch is not fully correct. Please check resource
> availability during allocation. I wouldn't expect an error from
> get_assigned_resources because of resource exhaustion.
>

Another option, since allocation functions (except DSC) already have
these safety checks: check error message to mention internal
inconstency: allocated resource doesn't exist.

--
With best wishes
Dmitry

\
 
 \ /
  Last update: 2023-03-26 23:32    [W:0.063 / U:0.812 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site