On 03-Jul-2018 11:12 PM, "Matthew Wilcox" willy@infradead.org wrote:
On Tue, Jul 03, 2018 at 09:40:43PM +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.
see commit 1c8f422059ae ("mm: change return type to vm_fault_t") for reference.
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.
I really think this changelog could do with more work. Specifically for this patch, I'd just say:
Convert v3d_gem_fault to return vm_fault_t
Instead of converting an errno into a vm_fault_t ourselves, use vmf_insert_mixed() which returns a vm_fault_t directly.
unsigned long pfn; pgoff_t pgoff;
int ret; /* We don't use vmf->pgoff since that has the fake offset: */ pgoff = (vmf->address - vma->vm_start) >> PAGE_SHIFT; pfn = page_to_pfn(bo->pages[pgoff]);ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn,
PFN_DEV));
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_mixed(vma, vmf->address,__pfn_to_pfn_t(pfn, PFN_DEV));}
The line-split here is kind of ugly. I'd do a little more extensive
surgery:
unsigned long pfn;
pfn_t pfn;
pfn = page_to_pfn(bo->pages[pgoff]);
pfn = __pfn_to_pfn_t(page_to_pfn(bo->pages[pgoff]), PFN_DEV);return vmf_insert_mixed(vma, vmf->address, pfn);
Ok, I will add the same and send v2.