On 5/10/2024 1:09 PM, Zhang, Jesse(Jie) wrote: > [AMD Official Use Only - General] > > Hi Lijo, > > -----Original Message----- > From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Lazar, Lijo > Sent: Friday, May 10, 2024 3:16 PM > To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH 19/22] drm/amdgpu: Fix the warning division or modulo by zero for the variable num_xcc_per_xcp > > > > On 5/10/2024 8:20 AM, Jesse Zhang wrote: >> Dividing expression num_xcc_per_xcp which may be zero has undefined behavior. >> >> Signed-off-by: Jesse Zhang <Jesse.Zhang@xxxxxxx> >> --- >> drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c >> b/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c >> index 414ea3f560a7..5752c6760992 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c >> +++ b/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c >> @@ -522,6 +522,9 @@ static int aqua_vanjaram_switch_partition_mode(struct amdgpu_xcp_mgr *xcp_mgr, >> goto unlock; >> >> num_xcc_per_xcp = __aqua_vanjaram_get_xcc_per_xcp(xcp_mgr, mode); >> + if (!num_xcc_per_xcp) >> + goto unlock; >> + > > This won't happen as the mode is validated before and for each valid mode a non-zero num_xcc_per_xcp is expected. To satisfy the warning-checker, before going to unlock use a proper 'ret' value also (otherwise it will look odd). > > [Zhang, Jesse(Jie)] Is that possible? > When the initialization mode is AMDGPU_AUTO_COMPUTE_PARTITION_MODE, > and get AMDGPU_UNKNOWN_COMPUTE_PARTITION_MODE through __aqua_vanjaram_get_auto_mode. > > If so, it will skip the valid mode function (__aqua_vanjaram_is_valid_mode). > Yes, that is possible. If auto detection cannot figure out a valid mode, then it needs to return an error from there without proceeding further. That is a better fix. Thanks, Lijo > Thanks > Jesse > > > Thanks, > Lijo > >> if (adev->gfx.funcs->switch_partition_mode) >> adev->gfx.funcs->switch_partition_mode(xcp_mgr->adev, >> num_xcc_per_xcp);
