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@gmail.com

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