2023-03-29 23:18:44

by Tom Rix

Subject: [PATCH] drm/nouveau/svm: remove unused ret variable

clang with W=1 reports
drivers/gpu/drm/nouveau/nouveau_svm.c:929:6: error: variable
'ret' set but not used [-Werror,-Wunused-but-set-variable]
int ret;
^
This variable is not used so remove it.

Signed-off-by: Tom Rix <[email protected]>
---
drivers/gpu/drm/nouveau/nouveau_svm.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index a74ba8d84ba7..e072d610f2f9 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -926,15 +926,14 @@ nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
unsigned long addr, u64 *pfns, unsigned long npages)
{
struct nouveau_pfnmap_args *args = nouveau_pfns_to_args(pfns);
- int ret;

args->p.addr = addr;
args->p.size = npages << PAGE_SHIFT;

mutex_lock(&svmm->mutex);

- ret = nvif_object_ioctl(&svmm->vmm->vmm.object, args,
- struct_size(args, p.phys, npages), NULL);
+ nvif_object_ioctl(&svmm->vmm->vmm.object, args,
+ struct_size(args, p.phys, npages), NULL);

mutex_unlock(&svmm->mutex);
}
--
2.27.0

2023-04-07 18:02:28

by Nick Desaulniers

Subject: Re: [PATCH] drm/nouveau/svm: remove unused ret variable

On Wed, Mar 29, 2023 at 4:14 PM Tom Rix <[email protected]> wrote:
>
> clang with W=1 reports
> drivers/gpu/drm/nouveau/nouveau_svm.c:929:6: error: variable
> 'ret' set but not used [-Werror,-Wunused-but-set-variable]
> int ret;
> ^
> This variable is not used so remove it.
>
> Signed-off-by: Tom Rix <[email protected]>
> ---
> drivers/gpu/drm/nouveau/nouveau_svm.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> index a74ba8d84ba7..e072d610f2f9 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -926,15 +926,14 @@ nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
> unsigned long addr, u64 *pfns, unsigned long npages)
> {
> struct nouveau_pfnmap_args *args = nouveau_pfns_to_args(pfns);
> - int ret;
>
> args->p.addr = addr;
> args->p.size = npages << PAGE_SHIFT;
>
> mutex_lock(&svmm->mutex);
>
> - ret = nvif_object_ioctl(&svmm->vmm->vmm.object, args,
> - struct_size(args, p.phys, npages), NULL);
> + nvif_object_ioctl(&svmm->vmm->vmm.object, args,
> + struct_size(args, p.phys, npages), NULL);

nvif_object_ioctl() may return -ENOSYS. Seeing other call sites have
comments like:
114 /*XXX: warn? */
134 /*XXX: warn? */

or other places where the return code isn't checked makes me think
that a better approach would be to
1. plumb error codes back up through nouveau_pfns_map() (and other
call sites of nvif_object_ioctl)
2. consider making nvif_object_ioctl __must_check

>
> mutex_unlock(&svmm->mutex);
> }
> --
> 2.27.0
>


--
Thanks,
~Nick Desaulniers