On Tue, Apr 17, 2018 at 07:17:55PM +0530, Souptick Joarder wrote:
> Use new return type vm_fault_t for fault handler. For
> now, this is just documenting that the function returns
> a VM_FAULT value rather than an errno. Once all instances
> are converted, vm_fault_t will become a distinct type.
>
> Reference id -> 1c8f422059ae ("mm: change return type to
> vm_fault_t")
>
> Previously vm_insert_page() returns err which driver
> mapped into VM_FAULT_* type. The new function
> vmf_insert_page() will replace this inefficiency by
> returning VM_FAULT_* type.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> ---
> drivers/gpu/drm/tegra/gem.c | 18 ++----------------
> 1 file changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> index 49b9bf2..6121493 100644
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@ -422,14 +422,13 @@ int tegra_bo_dumb_create(struct drm_file *file, struct drm_device *drm,
> return 0;
> }
>
> -static int tegra_bo_fault(struct vm_fault *vmf)
> +static vm_fault_t tegra_bo_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> struct drm_gem_object *gem = vma->vm_private_data;
> struct tegra_bo *bo = to_tegra_bo(gem);
> struct page *page;
> pgoff_t offset;
> - int err;
>
> if (!bo->pages)
> return VM_FAULT_SIGBUS;
> @@ -437,20 +436,7 @@ static int tegra_bo_fault(struct vm_fault *vmf)
> offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
> page = bo->pages[offset];
>
> - err = vm_insert_page(vma, vmf->address, page);
> - switch (err) {
> - case -EAGAIN:
> - case 0:
> - case -ERESTARTSYS:
> - case -EINTR:
> - case -EBUSY:
> - return VM_FAULT_NOPAGE;
> -
> - case -ENOMEM:
> - return VM_FAULT_OOM;
> - }
> -
> - return VM_FAULT_SIGBUS;
> + return vmf_insert_page(vma, vmf->address, page);
> }
This new function returns VM_FAULT_NOPAGE only for 0 and -EBUSY, whereas
we used to return VM_FAULT_NOPAGE for -EAGAIN, -ERESTARTSYS and -EINTR
as well. Was this previously wrong?
Thierry
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