[PATCH v3] gpu: drm: etnaviv: Change return type to vm_fault_t

[Souptick Joarder]

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_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.

vmf_error() is the newly introduce inline function
in 4.17-rc6.

Signed-off-by: Souptick Joarder <jrdr.linux at gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox at microsoft.com>
---
v2: mutex_lock_killable() is replaced with previous
    mutex_lock_interruptible() cause that discussion
    is not yet reached to any conclusion.

v3: updated the change log.

 drivers/gpu/drm/etnaviv/etnaviv_drv.h |  3 ++-
 drivers/gpu/drm/etnaviv/etnaviv_gem.c | 37 +++++++++--------------------------
 2 files changed, 11 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
index a54f0b7..f6777f0 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
@@ -28,6 +28,7 @@
 #include <linux/list.h>
 #include <linux/types.h>
 #include <linux/sizes.h>
+#include <linux/mm_types.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
@@ -62,7 +63,7 @@ int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
 		struct drm_file *file);
 
 int etnaviv_gem_mmap(struct file *filp, struct vm_area_struct *vma);
-int etnaviv_gem_fault(struct vm_fault *vmf);
+vm_fault_t etnaviv_gem_fault(struct vm_fault *vmf);
 int etnaviv_gem_mmap_offset(struct drm_gem_object *obj, u64 *offset);
 struct sg_table *etnaviv_gem_prime_get_sg_table(struct drm_gem_object *obj);
 void *etnaviv_gem_prime_vmap(struct drm_gem_object *obj);
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index fcc969f..b36e1ef 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -180,31 +180,30 @@ int etnaviv_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 	return obj->ops->mmap(obj, vma);
 }
 
-int etnaviv_gem_fault(struct vm_fault *vmf)
+vm_fault_t etnaviv_gem_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_gem_object *obj = vma->vm_private_data;
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);
 	struct page **pages, *page;
 	pgoff_t pgoff;
-	int ret;
+	int err;
 
 	/*
 	 * Make sure we don't parallel update on a fault, nor move or remove
-	 * something from beneath our feet.  Note that vm_insert_page() is
+	 * something from beneath our feet.  Note that vmf_insert_page() is
 	 * specifically coded to take care of this, so we don't have to.
 	 */
-	ret = mutex_lock_interruptible(&etnaviv_obj->lock);
-	if (ret)
-		goto out;
-
+	err = mutex_lock_interruptible(&etnaviv_obj->lock);
+	if (err)
+		return VM_FAULT_NOPAGE;
 	/* make sure we have pages attached now */
 	pages = etnaviv_gem_get_pages(etnaviv_obj);
 	mutex_unlock(&etnaviv_obj->lock);
 
 	if (IS_ERR(pages)) {
-		ret = PTR_ERR(pages);
-		goto out;
+		err = PTR_ERR(pages);
+		return vmf_error(err);
 	}
 
 	/* We don't use vmf->pgoff since that has the fake offset: */
@@ -215,25 +214,7 @@ int etnaviv_gem_fault(struct vm_fault *vmf)
 	VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
 	     page_to_pfn(page), page_to_pfn(page) << PAGE_SHIFT);
 
-	ret = vm_insert_page(vma, vmf->address, page);
-
-out:
-	switch (ret) {
-	case -EAGAIN:
-	case 0:
-	case -ERESTARTSYS:
-	case -EINTR:
-	case -EBUSY:
-		/*
-		 * EBUSY is ok: this just means that another thread
-		 * already did the job.
-		 */
-		return VM_FAULT_NOPAGE;
-	case -ENOMEM:
-		return VM_FAULT_OOM;
-	default:
-		return VM_FAULT_SIGBUS;
-	}
+	return vmf_insert_page(vma, vmf->address, page);
 }
 
 int etnaviv_gem_mmap_offset(struct drm_gem_object *obj, u64 *offset)
-- 
1.9.1