[00/14] drm/amd/pm: Replace one-element arrays with flexible-array members
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Gustavo A. R. Silva Oct. 7, 2020, 4:01 p.m. UTC
Hi all,

This series aims to replace one-element arrays with flexible-array
members.

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Refactor the code according to the use of flexible-array members, instead
of one-element arrays, and use the struct_size() helper to calculate the
size for the dynamic memory allocation.

Also, save some heap space in the process. More on this on each individual
patch.

This series also addresses multiple of the following sorts of warnings:

drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu8_hwmgr.c:1515:37:
warning: array subscript 1 is above array bounds of ‘const struct
phm_clock_voltage_dependency_record[1]’ [-Warray-bounds]

which, in this case, they are false positives, but nervertheless should be
fixed in order to enable -Warray-bounds[3][4].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays
[3] https://git.kernel.org/linus/44720996e2d79e47d508b0abe99b931a726a3197
[4] https://github.com/KSPP/linux/issues/109

Gustavo A. R. Silva (14):
  drm/amd/pm: Replace one-element array with flexible-array member
  drm/amd/pm: Replace one-element array with flexible-array member in
    struct vi_dpm_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_clock_array
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_uvd_clock_voltage_dependency_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_acp_clock_voltage_dependency_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_phase_shedding_limits_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_vce_clock_voltage_dependency_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_cac_leakage_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_samu_clock_voltage_dependency_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_ppt_v1_clock_voltage_dependency_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_ppt_v1_mm_clock_voltage_dependency_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_ppt_v1_voltage_lookup_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    phm_ppt_v1_pcie_table
  drm/amd/pm: Replace one-element array with flexible-array in struct
    ATOM_Vega10_GFXCLK_Dependency_Table

 drivers/gpu/drm/amd/pm/inc/hwmgr.h            | 20 ++---
 .../drm/amd/pm/powerplay/hwmgr/hwmgr_ppt.h    |  8 +-
 .../powerplay/hwmgr/process_pptables_v1_0.c   | 85 +++++++-----------
 .../amd/pm/powerplay/hwmgr/processpptables.c  | 85 +++++++-----------
 .../drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c   |  2 +-
 .../drm/amd/pm/powerplay/hwmgr/smu_helper.c   |  5 +-
 .../amd/pm/powerplay/hwmgr/vega10_pptable.h   |  2 +-
 .../powerplay/hwmgr/vega10_processpptables.c  | 88 ++++++-------------
 8 files changed, 107 insertions(+), 188 deletions(-)

Comments

Christian König Oct. 8, 2020, 7:19 a.m. UTC | #1
Am 07.10.20 um 18:01 schrieb Gustavo A. R. Silva:
> Hi all,
>
> This series aims to replace one-element arrays with flexible-array
> members.
>
> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use “flexible array members”[1] for these cases. The older
> style of one-element or zero-length arrays should no longer be used[2].
>
> Refactor the code according to the use of flexible-array members, instead
> of one-element arrays, and use the struct_size() helper to calculate the
> size for the dynamic memory allocation.
>
> Also, save some heap space in the process. More on this on each individual
> patch.

Ah! Nice to see that finally be documented and cleaned up.

Feel free to add an Acked-by: Christian König <christian.koenig@amd.com>

I also know about a case where we don't use struct_size in the DMA-buf code.

I'm the maintainer of that stuff as well, so be prepared to get patches 
thrown at you to clean that up as well.

Thanks,
Christian.

>
> This series also addresses multiple of the following sorts of warnings:
>
> drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu8_hwmgr.c:1515:37:
> warning: array subscript 1 is above array bounds of ‘const struct
> phm_clock_voltage_dependency_record[1]’ [-Warray-bounds]
>
> which, in this case, they are false positives, but nervertheless should be
> fixed in order to enable -Warray-bounds[3][4].
>
> [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFlexible_array_member&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=5LEWyR8pYSxmHsqhHiYiOS%2BPPk%2Fm5suOc6H7f5cIBL4%3D&amp;reserved=0
> [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Fv5.9-rc1%2Fprocess%2Fdeprecated.html%23zero-length-and-one-element-arrays&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=wOqxnNkA9FnOI%2BfB3dHn9RU7cqPJ62qqGCK9gsd2i%2Bo%3D&amp;reserved=0
> [3] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Flinus%2F44720996e2d79e47d508b0abe99b931a726a3197&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=x%2BSJeOrQA11HXoTaZEdyLyNWL9rC4GngDyoDMRBUn4M%3D&amp;reserved=0
> [4] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F109&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=48155uVo7AboCdSZfsTP10i2rHfBJctG%2F432lD%2BpfHo%3D&amp;reserved=0
>
> Gustavo A. R. Silva (14):
>    drm/amd/pm: Replace one-element array with flexible-array member
>    drm/amd/pm: Replace one-element array with flexible-array member in
>      struct vi_dpm_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_clock_array
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_uvd_clock_voltage_dependency_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_acp_clock_voltage_dependency_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_phase_shedding_limits_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_vce_clock_voltage_dependency_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_cac_leakage_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_samu_clock_voltage_dependency_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_ppt_v1_clock_voltage_dependency_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_ppt_v1_mm_clock_voltage_dependency_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_ppt_v1_voltage_lookup_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      phm_ppt_v1_pcie_table
>    drm/amd/pm: Replace one-element array with flexible-array in struct
>      ATOM_Vega10_GFXCLK_Dependency_Table
>
>   drivers/gpu/drm/amd/pm/inc/hwmgr.h            | 20 ++---
>   .../drm/amd/pm/powerplay/hwmgr/hwmgr_ppt.h    |  8 +-
>   .../powerplay/hwmgr/process_pptables_v1_0.c   | 85 +++++++-----------
>   .../amd/pm/powerplay/hwmgr/processpptables.c  | 85 +++++++-----------
>   .../drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c   |  2 +-
>   .../drm/amd/pm/powerplay/hwmgr/smu_helper.c   |  5 +-
>   .../amd/pm/powerplay/hwmgr/vega10_pptable.h   |  2 +-
>   .../powerplay/hwmgr/vega10_processpptables.c  | 88 ++++++-------------
>   8 files changed, 107 insertions(+), 188 deletions(-)
>
Gustavo A. R. Silva Oct. 8, 2020, 1:20 p.m. UTC | #2
On Thu, Oct 08, 2020 at 09:19:47AM +0200, Christian König wrote:
> Am 07.10.20 um 18:01 schrieb Gustavo A. R. Silva:
> > Hi all,
> > 
> > This series aims to replace one-element arrays with flexible-array
> > members.
> > 
> > There is a regular need in the kernel to provide a way to declare having
> > a dynamically sized set of trailing elements in a structure. Kernel code
> > should always use “flexible array members”[1] for these cases. The older
> > style of one-element or zero-length arrays should no longer be used[2].
> > 
> > Refactor the code according to the use of flexible-array members, instead
> > of one-element arrays, and use the struct_size() helper to calculate the
> > size for the dynamic memory allocation.
> > 
> > Also, save some heap space in the process. More on this on each individual
> > patch.
> 
> Ah! Nice to see that finally be documented and cleaned up.
> 
> Feel free to add an Acked-by: Christian König <christian.koenig@amd.com>
> 
> I also know about a case where we don't use struct_size in the DMA-buf code.
> 
> I'm the maintainer of that stuff as well, so be prepared to get patches
> thrown at you to clean that up as well.

No problem. Feel free to send all of those my way. :)

Thanks
--
Gustavo

> 
> Thanks,
> Christian.
> 
> > 
> > This series also addresses multiple of the following sorts of warnings:
> > 
> > drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu8_hwmgr.c:1515:37:
> > warning: array subscript 1 is above array bounds of ‘const struct
> > phm_clock_voltage_dependency_record[1]’ [-Warray-bounds]
> > 
> > which, in this case, they are false positives, but nervertheless should be
> > fixed in order to enable -Warray-bounds[3][4].
> > 
> > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFlexible_array_member&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=5LEWyR8pYSxmHsqhHiYiOS%2BPPk%2Fm5suOc6H7f5cIBL4%3D&amp;reserved=0
> > [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Fv5.9-rc1%2Fprocess%2Fdeprecated.html%23zero-length-and-one-element-arrays&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=wOqxnNkA9FnOI%2BfB3dHn9RU7cqPJ62qqGCK9gsd2i%2Bo%3D&amp;reserved=0
> > [3] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Flinus%2F44720996e2d79e47d508b0abe99b931a726a3197&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=x%2BSJeOrQA11HXoTaZEdyLyNWL9rC4GngDyoDMRBUn4M%3D&amp;reserved=0
> > [4] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F109&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=48155uVo7AboCdSZfsTP10i2rHfBJctG%2F432lD%2BpfHo%3D&amp;reserved=0
> > 
> > Gustavo A. R. Silva (14):
> >    drm/amd/pm: Replace one-element array with flexible-array member
> >    drm/amd/pm: Replace one-element array with flexible-array member in
> >      struct vi_dpm_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_clock_array
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_uvd_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_acp_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_phase_shedding_limits_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_vce_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_cac_leakage_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_samu_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_mm_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_voltage_lookup_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_pcie_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      ATOM_Vega10_GFXCLK_Dependency_Table
> > 
> >   drivers/gpu/drm/amd/pm/inc/hwmgr.h            | 20 ++---
> >   .../drm/amd/pm/powerplay/hwmgr/hwmgr_ppt.h    |  8 +-
> >   .../powerplay/hwmgr/process_pptables_v1_0.c   | 85 +++++++-----------
> >   .../amd/pm/powerplay/hwmgr/processpptables.c  | 85 +++++++-----------
> >   .../drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c   |  2 +-
> >   .../drm/amd/pm/powerplay/hwmgr/smu_helper.c   |  5 +-
> >   .../amd/pm/powerplay/hwmgr/vega10_pptable.h   |  2 +-
> >   .../powerplay/hwmgr/vega10_processpptables.c  | 88 ++++++-------------
> >   8 files changed, 107 insertions(+), 188 deletions(-)
> > 
>
Alex Deucher Oct. 8, 2020, 3:53 p.m. UTC | #3
On Thu, Oct 8, 2020 at 3:20 AM Christian König <christian.koenig@amd.com> wrote:
>
> Am 07.10.20 um 18:01 schrieb Gustavo A. R. Silva:
> > Hi all,
> >
> > This series aims to replace one-element arrays with flexible-array
> > members.
> >
> > There is a regular need in the kernel to provide a way to declare having
> > a dynamically sized set of trailing elements in a structure. Kernel code
> > should always use “flexible array members”[1] for these cases. The older
> > style of one-element or zero-length arrays should no longer be used[2].
> >
> > Refactor the code according to the use of flexible-array members, instead
> > of one-element arrays, and use the struct_size() helper to calculate the
> > size for the dynamic memory allocation.
> >
> > Also, save some heap space in the process. More on this on each individual
> > patch.
>
> Ah! Nice to see that finally be documented and cleaned up.
>
> Feel free to add an Acked-by: Christian König <christian.koenig@amd.com>

Applied 1-13.  patch 14 is changing a file shared with firmware, so I
left it for consistency.

Thanks!

Alex

>
> I also know about a case where we don't use struct_size in the DMA-buf code.
>
> I'm the maintainer of that stuff as well, so be prepared to get patches
> thrown at you to clean that up as well.
>
> Thanks,
> Christian.
>
> >
> > This series also addresses multiple of the following sorts of warnings:
> >
> > drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu8_hwmgr.c:1515:37:
> > warning: array subscript 1 is above array bounds of ‘const struct
> > phm_clock_voltage_dependency_record[1]’ [-Warray-bounds]
> >
> > which, in this case, they are false positives, but nervertheless should be
> > fixed in order to enable -Warray-bounds[3][4].
> >
> > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFlexible_array_member&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=5LEWyR8pYSxmHsqhHiYiOS%2BPPk%2Fm5suOc6H7f5cIBL4%3D&amp;reserved=0
> > [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Fv5.9-rc1%2Fprocess%2Fdeprecated.html%23zero-length-and-one-element-arrays&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=wOqxnNkA9FnOI%2BfB3dHn9RU7cqPJ62qqGCK9gsd2i%2Bo%3D&amp;reserved=0
> > [3] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Flinus%2F44720996e2d79e47d508b0abe99b931a726a3197&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=x%2BSJeOrQA11HXoTaZEdyLyNWL9rC4GngDyoDMRBUn4M%3D&amp;reserved=0
> > [4] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F109&amp;data=02%7C01%7Cchristian.koenig%40amd.com%7C5312862a3b8c41838ef508d86ad969c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637376829947099179&amp;sdata=48155uVo7AboCdSZfsTP10i2rHfBJctG%2F432lD%2BpfHo%3D&amp;reserved=0
> >
> > Gustavo A. R. Silva (14):
> >    drm/amd/pm: Replace one-element array with flexible-array member
> >    drm/amd/pm: Replace one-element array with flexible-array member in
> >      struct vi_dpm_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_clock_array
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_uvd_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_acp_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_phase_shedding_limits_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_vce_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_cac_leakage_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_samu_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_mm_clock_voltage_dependency_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_voltage_lookup_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      phm_ppt_v1_pcie_table
> >    drm/amd/pm: Replace one-element array with flexible-array in struct
> >      ATOM_Vega10_GFXCLK_Dependency_Table
> >
> >   drivers/gpu/drm/amd/pm/inc/hwmgr.h            | 20 ++---
> >   .../drm/amd/pm/powerplay/hwmgr/hwmgr_ppt.h    |  8 +-
> >   .../powerplay/hwmgr/process_pptables_v1_0.c   | 85 +++++++-----------
> >   .../amd/pm/powerplay/hwmgr/processpptables.c  | 85 +++++++-----------
> >   .../drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c   |  2 +-
> >   .../drm/amd/pm/powerplay/hwmgr/smu_helper.c   |  5 +-
> >   .../amd/pm/powerplay/hwmgr/vega10_pptable.h   |  2 +-
> >   .../powerplay/hwmgr/vega10_processpptables.c  | 88 ++++++-------------
> >   8 files changed, 107 insertions(+), 188 deletions(-)
> >
>
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