diff mbox series

[2/2] drm/imagination: avoid -Woverflow warning

Message ID 20231129113825.2961913-2-arnd@kernel.org (mailing list archive)
State New, archived
Headers show
Series [1/2] drm/imagination: avoid -Wmissing-prototype warnings | expand

Commit Message

Arnd Bergmann Nov. 29, 2023, 11:33 a.m. UTC
From: Arnd Bergmann <arnd@arndb.de>

The array size calculation in pvr_vm_mips_fini() appears to be incorrect based on
taking the size of the pointer rather than the size of the array, which manifests
as a warning about signed integer overflow:

In file included from include/linux/kernel.h:16,
                 from drivers/gpu/drm/imagination/pvr_rogue_fwif.h:10,
                 from drivers/gpu/drm/imagination/pvr_ccb.h:7,
                 from drivers/gpu/drm/imagination/pvr_device.h:7,
                 from drivers/gpu/drm/imagination/pvr_vm_mips.c:4:
drivers/gpu/drm/imagination/pvr_vm_mips.c: In function 'pvr_vm_mips_fini':
include/linux/array_size.h:11:25: error: overflow in conversion from 'long unsigned int' to 'int' changes value from '18446744073709551615' to '-1' [-Werror=overflow]
   11 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
      |                         ^
drivers/gpu/drm/imagination/pvr_vm_mips.c:106:24: note: in expansion of macro 'ARRAY_SIZE'
  106 |         for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
      |                        ^~~~~~~~~~

Just use the number of array elements directly here, and in the corresponding
init function for consistency.

Fixes: 927f3e0253c1 ("drm/imagination: Implement MIPS firmware processor and MMU support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/imagination/pvr_vm_mips.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Donald Robson Nov. 29, 2023, 12:01 p.m. UTC | #1
Hello Arnd,

Thanks for the patch.  I'm slightly concerned that we've not seen this warning when
building here.  I guess we need to check our CI settings...

Reviewed-by: Donald Robson <donald.robson@imgtec.com>

On Wed, 2023-11-29 at 12:33 +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The array size calculation in pvr_vm_mips_fini() appears to be incorrect based on
> taking the size of the pointer rather than the size of the array, which manifests
> as a warning about signed integer overflow:
> 
> In file included from include/linux/kernel.h:16,
>                  from drivers/gpu/drm/imagination/pvr_rogue_fwif.h:10,
>                  from drivers/gpu/drm/imagination/pvr_ccb.h:7,
>                  from drivers/gpu/drm/imagination/pvr_device.h:7,
>                  from drivers/gpu/drm/imagination/pvr_vm_mips.c:4:
> drivers/gpu/drm/imagination/pvr_vm_mips.c: In function 'pvr_vm_mips_fini':
> include/linux/array_size.h:11:25: error: overflow in conversion from 'long unsigned int' to 'int' changes value from '18446744073709551615' to '-1' [-Werror=overflow]
>    11 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>       |                         ^
> drivers/gpu/drm/imagination/pvr_vm_mips.c:106:24: note: in expansion of macro 'ARRAY_SIZE'
>   106 |         for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
>       |                        ^~~~~~~~~~
> 
> Just use the number of array elements directly here, and in the corresponding
> init function for consistency.
> 
> Fixes: 927f3e0253c1 ("drm/imagination: Implement MIPS firmware processor and MMU support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/imagination/pvr_vm_mips.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imagination/pvr_vm_mips.c b/drivers/gpu/drm/imagination/pvr_vm_mips.c
> index 7268cf6e630b..6c2e4cc4e6db 100644
> --- a/drivers/gpu/drm/imagination/pvr_vm_mips.c
> +++ b/drivers/gpu/drm/imagination/pvr_vm_mips.c
> @@ -46,7 +46,7 @@ pvr_vm_mips_init(struct pvr_device *pvr_dev)
>  	if (!mips_data)
>  		return -ENOMEM;
>  
> -	for (page_nr = 0; page_nr < ARRAY_SIZE(mips_data->pt_pages); page_nr++) {
> +	for (page_nr = 0; page_nr < PVR_MIPS_PT_PAGE_COUNT; page_nr++) {
>  		mips_data->pt_pages[page_nr] = alloc_page(GFP_KERNEL | __GFP_ZERO);
>  		if (!mips_data->pt_pages[page_nr]) {
>  			err = -ENOMEM;
> @@ -103,7 +103,7 @@ pvr_vm_mips_fini(struct pvr_device *pvr_dev)
>  	int page_nr;
>  
>  	vunmap(mips_data->pt);
> -	for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
> +	for (page_nr = PVR_MIPS_PT_PAGE_COUNT - 1; page_nr >= 0; page_nr--) {
>  		dma_unmap_page(from_pvr_device(pvr_dev)->dev,
>  			       mips_data->pt_dma_addr[page_nr], PAGE_SIZE, DMA_TO_DEVICE);
>
Arnd Bergmann Nov. 29, 2023, 12:04 p.m. UTC | #2
On Wed, Nov 29, 2023, at 13:01, Donald Robson wrote:
> Hello Arnd,
>
> Thanks for the patch.  I'm slightly concerned that we've not seen this 
> warning when
> building here.  I guess we need to check our CI settings...
>
> Reviewed-by: Donald Robson <donald.robson@imgtec.com>

This was previously enabled only when building with either
"make W=1" or "make C=1", but not the default build, which
explains why it only showed up after the merge into linux-next
that has the corresponding scripts/Makefile.extrawarn change.

It would still be a good idea to add the extra compiler (W=1)
and sparse (C=1) warnings in your CI system and address all
other issues that might uncover.

      Arnd
Donald Robson Nov. 29, 2023, 12:15 p.m. UTC | #3
On Wed, 2023-11-29 at 13:04 +0100, Arnd Bergmann wrote:
> *** CAUTION: This email originates from a source not known to Imagination Technologies. Think before you click a link or open an attachment ***
> 
> On Wed, Nov 29, 2023, at 13:01, Donald Robson wrote:
> > Hello Arnd,
> > 
> > Thanks for the patch.  I'm slightly concerned that we've not seen this 
> > warning when
> > building here.  I guess we need to check our CI settings...
> > 
> > Reviewed-by: Donald Robson <donald.robson@imgtec.com>
> 
> This was previously enabled only when building with either
> "make W=1" or "make C=1", but not the default build, which
> explains why it only showed up after the merge into linux-next
> that has the corresponding scripts/Makefile.extrawarn change.
> 
> It would still be a good idea to add the extra compiler (W=1)
> and sparse (C=1) warnings in your CI system and address all
> other issues that might uncover.
> 
>       Arnd

Thanks Arnd, we will do this.
diff mbox series

Patch

diff --git a/drivers/gpu/drm/imagination/pvr_vm_mips.c b/drivers/gpu/drm/imagination/pvr_vm_mips.c
index 7268cf6e630b..6c2e4cc4e6db 100644
--- a/drivers/gpu/drm/imagination/pvr_vm_mips.c
+++ b/drivers/gpu/drm/imagination/pvr_vm_mips.c
@@ -46,7 +46,7 @@  pvr_vm_mips_init(struct pvr_device *pvr_dev)
 	if (!mips_data)
 		return -ENOMEM;
 
-	for (page_nr = 0; page_nr < ARRAY_SIZE(mips_data->pt_pages); page_nr++) {
+	for (page_nr = 0; page_nr < PVR_MIPS_PT_PAGE_COUNT; page_nr++) {
 		mips_data->pt_pages[page_nr] = alloc_page(GFP_KERNEL | __GFP_ZERO);
 		if (!mips_data->pt_pages[page_nr]) {
 			err = -ENOMEM;
@@ -103,7 +103,7 @@  pvr_vm_mips_fini(struct pvr_device *pvr_dev)
 	int page_nr;
 
 	vunmap(mips_data->pt);
-	for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
+	for (page_nr = PVR_MIPS_PT_PAGE_COUNT - 1; page_nr >= 0; page_nr--) {
 		dma_unmap_page(from_pvr_device(pvr_dev)->dev,
 			       mips_data->pt_dma_addr[page_nr], PAGE_SIZE, DMA_TO_DEVICE);