Messages in this thread | | | Date | Wed, 18 Jan 2023 03:30:20 +0200 | Subject | Re: [PATCH v3] drm/msm/dpu: Disallow unallocated resources to be returned | From | Dmitry Baryshkov <> |
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On 10/01/2023 01:15, 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, until their allocation/assignment is being sanity-checked in > "drm/msm/dpu: Reject topologies for which no DSC blocks are available") > 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> > --- > > Changes since v2: > - Dropped all 7 other patches that were queued for -next; > - Reworded error message to clarify that the requested resource should > have already been allocated, rather than sounding like > dpu_rm_get_assigned_resources is (re)allocating/(re)assigning > resources here; > - This patch is now (implicitly!) based after "drm/msm/dpu: Reject > topologies for which no DSC blocks are available", which should make > it impossible to reach this condition, making it more of a safeguard > in case of future code changes and/or hidden issues: and is more > clearly conveyed in the patch message as well. > > v2: https://lore.kernel.org/linux-arm-msm/20221221231943.1961117-5-marijn.suijten@somainline.org/ > > drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 5 +++++ > 1 file changed, 5 insertions(+)
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
-- With best wishes Dmitry
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