diff mbox series

[v2,5/6] PCI: iproc: fix -Wvoid-pointer-to-enum-cast warning

Message ID 20231114055456.2231990-6-yoshihiro.shimoda.uh@renesas.com (mailing list archive)
State Superseded
Delegated to: Geert Uytterhoeven
Headers show
Series PCI: controllers: tidy code up | expand

Commit Message

Yoshihiro Shimoda Nov. 14, 2023, 5:54 a.m. UTC 
From: Justin Stitt <justinstitt@google.com>

When building with clang 18 I see the following warning:
|       drivers/pci/controller/pcie-iproc-platform.c:55:15: warning: cast to smaller
|                integer type 'enum iproc_pcie_type' from 'const void *' [-Wvoid-pointer-to-enum-cast]
|          55 |         pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);

This is due to the fact that `of_device_get_match_data` returns a void*
while `enum iproc_pcie_type` has the size of an int. This leads to
truncation and possible data loss.

Link: https://github.com/ClangBuiltLinux/linux/issues/1910
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/pci/controller/pcie-iproc-platform.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Geert Uytterhoeven Nov. 14, 2023, 8:10 a.m. UTC | #1 
On Tue, Nov 14, 2023 at 6:55 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@renesas.com> wrote:
> From: Justin Stitt <justinstitt@google.com>
>
> When building with clang 18 I see the following warning:
> |       drivers/pci/controller/pcie-iproc-platform.c:55:15: warning: cast to smaller
> |                integer type 'enum iproc_pcie_type' from 'const void *' [-Wvoid-pointer-to-enum-cast]
> |          55 |         pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
>
> This is due to the fact that `of_device_get_match_data` returns a void*
> while `enum iproc_pcie_type` has the size of an int. This leads to
> truncation and possible data loss.

Note that in this case there is no data loss, as the original value
stored is of type enum iproc_pcie_type.

> Link: https://github.com/ClangBuiltLinux/linux/issues/1910
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert
Manivannan Sadhasivam Nov. 17, 2023, 9:21 a.m. UTC | #2 
On Tue, Nov 14, 2023 at 02:54:55PM +0900, Yoshihiro Shimoda wrote:
> From: Justin Stitt <justinstitt@google.com>
> 
> When building with clang 18 I see the following warning:
> |       drivers/pci/controller/pcie-iproc-platform.c:55:15: warning: cast to smaller
> |                integer type 'enum iproc_pcie_type' from 'const void *' [-Wvoid-pointer-to-enum-cast]
> |          55 |         pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
> 
> This is due to the fact that `of_device_get_match_data` returns a void*
> while `enum iproc_pcie_type` has the size of an int. This leads to
> truncation and possible data loss.
> 

As Geert noted, this statement is wrong as there is no possible data loss in
this driver. Please fix it in next version.

> Link: https://github.com/ClangBuiltLinux/linux/issues/1910
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/pci/controller/pcie-iproc-platform.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-iproc-platform.c b/drivers/pci/controller/pcie-iproc-platform.c
> index acdc583d2980..83cbc95f4384 100644
> --- a/drivers/pci/controller/pcie-iproc-platform.c
> +++ b/drivers/pci/controller/pcie-iproc-platform.c
> @@ -52,7 +52,7 @@ static int iproc_pltfm_pcie_probe(struct platform_device *pdev)
>  	pcie = pci_host_bridge_priv(bridge);
>  
>  	pcie->dev = dev;
> -	pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
> +	pcie->type = (uintptr_t) of_device_get_match_data(dev);
>  
>  	ret = of_address_to_resource(np, 0, &reg);
>  	if (ret < 0) {
> -- 
> 2.34.1
>
Yoshihiro Shimoda Dec. 15, 2023, 1:20 a.m. UTC | #3 
Hello Manivannan,

> From: Manivannan Sadhasivam, Sent: Friday, November 17, 2023 6:22 PM
> 
> On Tue, Nov 14, 2023 at 02:54:55PM +0900, Yoshihiro Shimoda wrote:
> > From: Justin Stitt <justinstitt@google.com>
> >
> > When building with clang 18 I see the following warning:
> > |       drivers/pci/controller/pcie-iproc-platform.c:55:15: warning: cast to smaller
> > |                integer type 'enum iproc_pcie_type' from 'const void *' [-Wvoid-pointer-to-enum-cast]
> > |          55 |         pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
> >
> > This is due to the fact that `of_device_get_match_data` returns a void*
> > while `enum iproc_pcie_type` has the size of an int. This leads to
> > truncation and possible data loss.
> >
> 
> As Geert noted, this statement is wrong as there is no possible data loss in
> this driver. Please fix it in next version.

I got it. I'll drop this statement on v3.

> > Link:
<snip URL>
> > Reported-by: Nathan Chancellor <nathan@kernel.org>
> > Signed-off-by: Justin Stitt <justinstitt@google.com>
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thank you for your review!

Best regards,
Yoshihiro Shimoda

> - Mani
> 
> > ---
> >  drivers/pci/controller/pcie-iproc-platform.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/pcie-iproc-platform.c b/drivers/pci/controller/pcie-iproc-platform.c
> > index acdc583d2980..83cbc95f4384 100644
> > --- a/drivers/pci/controller/pcie-iproc-platform.c
> > +++ b/drivers/pci/controller/pcie-iproc-platform.c
> > @@ -52,7 +52,7 @@ static int iproc_pltfm_pcie_probe(struct platform_device *pdev)
> >  	pcie = pci_host_bridge_priv(bridge);
> >
> >  	pcie->dev = dev;
> > -	pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
> > +	pcie->type = (uintptr_t) of_device_get_match_data(dev);
> >
> >  	ret = of_address_to_resource(np, 0, &reg);
> >  	if (ret < 0) {
> > --
> > 2.34.1
> >
> 
> --
> மணிவண்ணன் சதாசிவம்
diff mbox series

Patch

diff --git a/drivers/pci/controller/pcie-iproc-platform.c b/drivers/pci/controller/pcie-iproc-platform.c
index acdc583d2980..83cbc95f4384 100644
--- a/drivers/pci/controller/pcie-iproc-platform.c
+++ b/drivers/pci/controller/pcie-iproc-platform.c
@@ -52,7 +52,7 @@  static int iproc_pltfm_pcie_probe(struct platform_device *pdev)
 	pcie = pci_host_bridge_priv(bridge);
 
 	pcie->dev = dev;
-	pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
+	pcie->type = (uintptr_t) of_device_get_match_data(dev);
 
 	ret = of_address_to_resource(np, 0, &reg);
 	if (ret < 0) {