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SubjectRe: [PATCH] gpu: drm: msm: Change return type to vm_fault_t
On Mon, May 21, 2018 at 10:59 PM, Souptick Joarder <jrdr.linux@gmail.com> 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() 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.linux@gmail.com>
> Reviewed-by: Matthew Wilcox <mawilcox@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
>

Any comment for this patch ?

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