Re: [PATCH] drm/amd/display: Correctly initialize some memory in get_available_dsc_slices()

[Hamza Mahfooz]

On 4/25/23 03:53, Christophe JAILLET wrote:

The intent here is to clear the 'available_slices' buffer before setting
some values in it.

This is an array of int, so in order to fully initialize it, we must clear
MIN_AVAILABLE_SLICES_SIZE * sizeof(int) bytes.

Compute the right length of the buffer when calling memset().

Fixes: 97bda0322b8a ("drm/amd/display: Add DSC support for Navi (v2)")
Signed-off-by: Christophe JAILLET 
---
NOT even compile-tested.

make -j7  drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.o

on my setup, it fails with:
   CC  drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.o
drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c:27:10: fatal error: dc_hw_types.h: 
Aucun fichier ou dossier de ce type
27 | #include "dc_hw_types.h"
   |  ^~~

I've not investigated why.
---
  drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c 
b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
index b9a05bb025db..1d7384b2be28 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -645,7 +645,7 @@ static int get_available_dsc_slices(union 
dsc_enc_slice_caps slice_caps, int *av
  {
int idx = 0;
  
-	memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE);

+   memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE * 
sizeof(*available_slices));


Actually, I believe we can drop this memset(). Since,
get_available_dsc_slices() returns the number of indices set, and all of
the users of get_available_dsc_slices() don't cross that bound.

  
  	if (slice_caps.bits.NUM_SLICES_1)

available_slices[idx++] = 1;

--
Hamza

[PATCH] drm/amd/display: Correctly initialize some memory in get_available_dsc_slices()

[Christophe JAILLET]

The intent here is to clear the 'available_slices' buffer before setting
some values in it.

This is an array of int, so in order to fully initialize it, we must clear
MIN_AVAILABLE_SLICES_SIZE * sizeof(int) bytes.

Compute the right length of the buffer when calling memset().

Fixes: 97bda0322b8a ("drm/amd/display: Add DSC support for Navi (v2)")
Signed-off-by: Christophe JAILLET 
---
NOT even compile-tested.

make -j7  drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.o

on my setup, it fails with:
  CC  drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.o
drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c:27:10: fatal error: dc_hw_types.h: 
Aucun fichier ou dossier de ce type
   27 | #include "dc_hw_types.h"
  |  ^~~

I've not investigated why.
---
 drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c 
b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
index b9a05bb025db..1d7384b2be28 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -645,7 +645,7 @@ static int get_available_dsc_slices(union 
dsc_enc_slice_caps slice_caps, int *av
 {
int idx = 0;
 
-   memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE);
+   memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE * 
sizeof(*available_slices));
 
if (slice_caps.bits.NUM_SLICES_1)
available_slices[idx++] = 1;
-- 
2.34.1