Re: [PATCH] vga_switcheroo: Fix impossible judgment condition
On Thu, Oct 26, 2023 at 04:46:29PM +0800, Su Hui wrote:
> On 2023/10/26 12:44, Dan Carpenter wrote:
> > On Thu, Oct 26, 2023 at 10:10:57AM +0800, Su Hui wrote:
> > > 'id' is enum type like unsigned int, so it will never be less than zero.
> > >
> > > Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to
> > > bound GPU id")
> > > Signed-off-by: Su Hui
> > > ---
> > > drivers/gpu/vga/vga_switcheroo.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/vga/vga_switcheroo.c
> > > b/drivers/gpu/vga/vga_switcheroo.c
> > > index 365e6ddbe90f..d3064466fd3a 100644
> > > --- a/drivers/gpu/vga/vga_switcheroo.c
> > > +++ b/drivers/gpu/vga/vga_switcheroo.c
> > > @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct
> > > pci_dev *pdev,
> > > mutex_lock(_mutex);
> > > if (vgasr_priv.active) {
> > > id = vgasr_priv.handler->get_client_id(vga_dev);
> > > - if (id < 0) {
> > > + if ((int)id < 0) {
> > Hi,
> >
> > I feel like you're using Smatch? Which is great! Fantastic!
> Yep, Smatch helps me a lot to find these bugs! I really like this excellent
> tool!
> >
> > Have you built the cross function database? If you have there is a
> > command that's useful.
> Not yet, bu I want to build this.
Yeah. It's super useful for kernel development. It helps to understand
how functions are called and where variables are set etc. The smatch
documentation is crap, I know. But I did write a short blog about the
cross function DB.
https://staticthinking.wordpress.com/2023/05/02/the-cross-function-db/
It's simple to build, but it takes a long time. Just run
smatch_scripts/build_kernel_data.sh
regards,
dan carpenter
Re: [PATCH] vga_switcheroo: Fix impossible judgment condition
On 2023/10/26 12:44, Dan Carpenter wrote:
On Thu, Oct 26, 2023 at 10:10:57AM +0800, Su Hui wrote:
'id' is enum type like unsigned int, so it will never be less than zero.
Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU
id")
Signed-off-by: Su Hui
---
drivers/gpu/vga/vga_switcheroo.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 365e6ddbe90f..d3064466fd3a 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev
*pdev,
mutex_lock(_mutex);
if (vgasr_priv.active) {
id = vgasr_priv.handler->get_client_id(vga_dev);
- if (id < 0) {
+ if ((int)id < 0) {
Hi,
I feel like you're using Smatch? Which is great! Fantastic!
Yep, Smatch helps me a lot to find these bugs! I really like this
excellent tool!
Have you built the cross function database? If you have there is a
command that's useful.
Not yet, bu I want to build this.
$ ~/smatch/smatch_db/smdb.py functions vga_switcheroo_handler get_client_id |
tee where
drivers/gpu/drm/nouveau/nouveau_acpi.c | (struct
vga_switcheroo_handler)->get_client_id | nouveau_dsm_get_client_id | 1
drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | (struct
vga_switcheroo_handler)->get_client_id | amdgpu_atpx_get_client_id | 1
drivers/gpu/drm/radeon/radeon_atpx_handler.c | (struct
vga_switcheroo_handler)->get_client_id | radeon_atpx_get_client_id | 1
drivers/platform/x86/apple-gmux.c | (struct
vga_switcheroo_handler)->get_client_id | gmux_get_client_id | 1
$ make cscope
$ vim where
Use cscope to jump to each of those four functions. Move the cursor to
the nouveau_dsm_get_client_id and hit CTRL-].
Sounds great! I must try this!
They never return negatives. The enum vga_switcheroo_client_id has a
VGA_SWITCHEROO_UNKNOWN_ID define which I guess these functions are
supposed to return on error. They never do return that, but I bet
that's what we are supposed to check for. It honestly might be good
to check for both...
if ((int)id < 0 || id == VGA_SWITCHEROO_UNKNOWN_ID) {
mutex_unlock(_mutex);
return -EINVAL;
}
Agreed, I will send v2 patch soon.
Really thanks for your wonderful suggestion! :)
Su Hui
regards,
dan carpenter
Re: [PATCH] vga_switcheroo: Fix impossible judgment condition
On Thu, Oct 26, 2023 at 10:10:57AM +0800, Su Hui wrote:
> 'id' is enum type like unsigned int, so it will never be less than zero.
>
> Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound
> GPU id")
> Signed-off-by: Su Hui
> ---
> drivers/gpu/vga/vga_switcheroo.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/vga/vga_switcheroo.c
> b/drivers/gpu/vga/vga_switcheroo.c
> index 365e6ddbe90f..d3064466fd3a 100644
> --- a/drivers/gpu/vga/vga_switcheroo.c
> +++ b/drivers/gpu/vga/vga_switcheroo.c
> @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev
> *pdev,
> mutex_lock(_mutex);
> if (vgasr_priv.active) {
> id = vgasr_priv.handler->get_client_id(vga_dev);
> - if (id < 0) {
> + if ((int)id < 0) {
Hi,
I feel like you're using Smatch? Which is great! Fantastic!
Have you built the cross function database? If you have there is a
command that's useful.
$ ~/smatch/smatch_db/smdb.py functions vga_switcheroo_handler get_client_id |
tee where
drivers/gpu/drm/nouveau/nouveau_acpi.c | (struct
vga_switcheroo_handler)->get_client_id | nouveau_dsm_get_client_id | 1
drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | (struct
vga_switcheroo_handler)->get_client_id | amdgpu_atpx_get_client_id | 1
drivers/gpu/drm/radeon/radeon_atpx_handler.c | (struct
vga_switcheroo_handler)->get_client_id | radeon_atpx_get_client_id | 1
drivers/platform/x86/apple-gmux.c | (struct
vga_switcheroo_handler)->get_client_id | gmux_get_client_id | 1
$ make cscope
$ vim where
Use cscope to jump to each of those four functions. Move the cursor to
the nouveau_dsm_get_client_id and hit CTRL-].
They never return negatives. The enum vga_switcheroo_client_id has a
VGA_SWITCHEROO_UNKNOWN_ID define which I guess these functions are
supposed to return on error. They never do return that, but I bet
that's what we are supposed to check for. It honestly might be good
to check for both...
if ((int)id < 0 || id == VGA_SWITCHEROO_UNKNOWN_ID) {
mutex_unlock(_mutex);
return -EINVAL;
}
regards,
dan carpenter
[PATCH] vga_switcheroo: Fix impossible judgment condition
'id' is enum type like unsigned int, so it will never be less than zero.
Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound
GPU id")
Signed-off-by: Su Hui
---
drivers/gpu/vga/vga_switcheroo.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 365e6ddbe90f..d3064466fd3a 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev
*pdev,
mutex_lock(_mutex);
if (vgasr_priv.active) {
id = vgasr_priv.handler->get_client_id(vga_dev);
- if (id < 0) {
+ if ((int)id < 0) {
mutex_unlock(_mutex);
return -EINVAL;
}
--
2.30.2
