On Thu, May 24, 2018 at 12:25 AM, Souptick Joarder <jrdr.linux@xxxxxxxxx> 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.
>
> Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")
>
> Previously vm_insert_{mixed,pfn} returns err which driver
> mapped into VM_FAULT_* type. The new function
> vmf_insert_{mixed,pfn} will replace this inefficiency by
> returning VM_FAULT_* type.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> ---
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 45 ++++++++++++++++++++---------------------
> 1 file changed, 22 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 8eba95b..2d13f03 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -43,10 +43,11 @@
>
> #define TTM_BO_VM_NUM_PREFAULT 16
>
> -static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
> +static vm_fault_t ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
> struct vm_fault *vmf)
> {
> - int ret = 0;
> + int err = 0;
> + vm_fault_t ret = 0;
>
> if (likely(!bo->moving))
> goto out_unlock;
> @@ -77,9 +78,9 @@ static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
> /*
> * Ordinary wait.
> */
> - ret = dma_fence_wait(bo->moving, true);
> - if (unlikely(ret != 0)) {
> - ret = (ret != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
> + err = dma_fence_wait(bo->moving, true);
> + if (unlikely(err != 0)) {
> + ret = (err != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
> VM_FAULT_NOPAGE;
> goto out_unlock;
> }
> @@ -104,7 +105,7 @@ static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo,
> + page_offset;
> }
>
> -static int ttm_bo_vm_fault(struct vm_fault *vmf)
> +static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
> @@ -115,8 +116,9 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
> unsigned long pfn;
> struct ttm_tt *ttm = NULL;
> struct page *page;
> - int ret;
> + int err;
> int i;
> + vm_fault_t ret = VM_FAULT_NOPAGE;
> unsigned long address = vmf->address;
> struct ttm_mem_type_manager *man =
> &bdev->man[bo->mem.mem_type];
> @@ -128,9 +130,9 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
> * for reserve, and if it fails, retry the fault after waiting
> * for the buffer to become unreserved.
> */
> - ret = ttm_bo_reserve(bo, true, true, NULL);
> - if (unlikely(ret != 0)) {
> - if (ret != -EBUSY)
> + err = ttm_bo_reserve(bo, true, true, NULL);
> + if (unlikely(err != 0)) {
> + if (err != -EBUSY)
> return VM_FAULT_NOPAGE;
>
> if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
> @@ -162,8 +164,8 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
> }
>
> if (bdev->driver->fault_reserve_notify) {
> - ret = bdev->driver->fault_reserve_notify(bo);
> - switch (ret) {
> + err = bdev->driver->fault_reserve_notify(bo);
> + switch (err) {
> case 0:
> break;
> case -EBUSY:
> @@ -191,13 +193,13 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
> goto out_unlock;
> }
>
> - ret = ttm_mem_io_lock(man, true);
> - if (unlikely(ret != 0)) {
> + err = ttm_mem_io_lock(man, true);
> + if (unlikely(err != 0)) {
> ret = VM_FAULT_NOPAGE;
> goto out_unlock;
> }
> - ret = ttm_mem_io_reserve_vm(bo);
> - if (unlikely(ret != 0)) {
> + err = ttm_mem_io_reserve_vm(bo);
> + if (unlikely(err != 0)) {
> ret = VM_FAULT_SIGBUS;
> goto out_io_unlock;
> }
> @@ -265,23 +267,20 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
> }
>
> if (vma->vm_flags & VM_MIXEDMAP)
> - ret = vm_insert_mixed(&cvma, address,
> + ret = vmf_insert_mixed(&cvma, address,
> __pfn_to_pfn_t(pfn, PFN_DEV));
> else
> - ret = vm_insert_pfn(&cvma, address, pfn);
> + ret = vmf_insert_pfn(&cvma, address, pfn);
>
> /*
> * Somebody beat us to this PTE or prefaulting to
> * an already populated PTE, or prefaulting error.
> */
>
> - if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
> + if (unlikely((ret == VM_FAULT_NOPAGE && i > 0)))
> break;
> - else if (unlikely(ret != 0)) {
> - ret =
> - (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
> + else if (unlikely(ret & VM_FAULT_ERROR))
> goto out_io_unlock;
> - }
>
> address += PAGE_SIZE;
> if (unlikely(++page_offset >= page_last))
> --
> 1.9.1
>
Any comment for this patch ?
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