[PATCH] gpu: drm: msm: 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_mixed() returns err which driver
mapped into VM_FAULT_* type. The new function 
vmf_insert_mixed() 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.li...@gmail.com>
Reviewed-by: Matthew Wilcox <mawil...@microsoft.com>
---
 drivers/gpu/drm/msm/msm_drv.h |  3 ++-
 drivers/gpu/drm/msm/msm_gem.c | 33 ++++++++++-----------------------
 2 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 0a653dd..44b4ca7 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -33,6 +33,7 @@
 #include <linux/of_graph.h>
 #include <linux/of_device.h>
 #include <asm/sizes.h>
+#include <linux/mm_types.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_atomic.h>
@@ -188,7 +189,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 int msm_gem_mmap_obj(struct drm_gem_object *obj,
                        struct vm_area_struct *vma);
 int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
-int msm_gem_fault(struct vm_fault *vmf);
+vm_fault_t msm_gem_fault(struct vm_fault *vmf);
 uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj);
 int msm_gem_get_iova(struct drm_gem_object *obj,
                struct msm_gem_address_space *aspace, uint64_t *iova);
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 07376de..27a5ab5 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -217,7 +217,7 @@ int msm_gem_mmap(struct file *filp, struct vm_area_struct 
*vma)
        return msm_gem_mmap_obj(vma->vm_private_data, vma);
 }
 
-int msm_gem_fault(struct vm_fault *vmf)
+vm_fault_t msm_gem_fault(struct vm_fault *vmf)
 {
        struct vm_area_struct *vma = vmf->vma;
        struct drm_gem_object *obj = vma->vm_private_data;
@@ -225,15 +225,18 @@ int msm_gem_fault(struct vm_fault *vmf)
        struct page **pages;
        unsigned long pfn;
        pgoff_t pgoff;
-       int ret;
+       int err;
+       vm_fault_t ret;
 
        /*
         * vm_ops.open/drm_gem_mmap_obj and close get and put
         * a reference on obj. So, we dont need to hold one here.
         */
-       ret = mutex_lock_interruptible(&msm_obj->lock);
-       if (ret)
+       err = mutex_lock_interruptible(&msm_obj->lock);
+       if (err) {
+               ret = VM_FAULT_NOPAGE;
                goto out;
+       }
 
        if (WARN_ON(msm_obj->madv != MSM_MADV_WILLNEED)) {
                mutex_unlock(&msm_obj->lock);
@@ -243,7 +246,7 @@ int msm_gem_fault(struct vm_fault *vmf)
        /* make sure we have pages attached now */
        pages = get_pages(obj);
        if (IS_ERR(pages)) {
-               ret = PTR_ERR(pages);
+               ret = vmf_error(PTR_ERR(pages));
                goto out_unlock;
        }
 
@@ -255,27 +258,11 @@ int msm_gem_fault(struct vm_fault *vmf)
        VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
                        pfn, pfn << PAGE_SHIFT);
 
-       ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV));
-
+       ret = vmf_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV));
 out_unlock:
        mutex_unlock(&msm_obj->lock);
 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 ret;
 }
 
 /** get mmap offset */
-- 
1.9.1