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>+ u64 flags = args->flags; >+ u64 valid_flags = 0; >+ >+ if (flags & ~valid_flags) >+ return -EINVAL; >+ >+ if (size < 0 || !PAGE_ALIGNED(size)) >+ return -EINVAL; is size == 0 a valid case? >+int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, >+ unsigned int fd, loff_t offset) >+{ >+ loff_t size = slot->npages << PAGE_SHIFT; >+ unsigned long start, end; >+ struct kvm_gmem *gmem; >+ struct inode *inode; >+ struct file *file; >+ >+ BUILD_BUG_ON(sizeof(gfn_t) != sizeof(slot->gmem.pgoff)); >+ >+ file = fget(fd); >+ if (!file) >+ return -EBADF; >+ >+ if (file->f_op != &kvm_gmem_fops) >+ goto err; >+ >+ gmem = file->private_data; >+ if (gmem->kvm != kvm) >+ goto err; >+ >+ inode = file_inode(file); >+ >+ if (offset < 0 || !PAGE_ALIGNED(offset)) >+ return -EINVAL; goto err; or hoist the check above fget(). >+ >+ if (offset + size > i_size_read(inode)) >+ goto err; >+ >+ filemap_invalidate_lock(inode->i_mapping); >+ >+ start = offset >> PAGE_SHIFT; >+ end = start + slot->npages; >+ >+ if (!xa_empty(&gmem->bindings) && >+ xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) { >+ filemap_invalidate_unlock(inode->i_mapping); >+ goto err; >+ } >+ >+ /* >+ * No synchronize_rcu() needed, any in-flight readers are guaranteed to >+ * be see either a NULL file or this new file, no need for them to go >+ * away. >+ */ >+ rcu_assign_pointer(slot->gmem.file, file); >+ slot->gmem.pgoff = start; >+ >+ xa_store_range(&gmem->bindings, start, end - 1, slot, GFP_KERNEL); >+ filemap_invalidate_unlock(inode->i_mapping); >+ >+ /* >+ * Drop the reference to the file, even on success. The file pins KVM, >+ * not the other way 'round. Active bindings are invalidated if the >+ * file is closed before memslots are destroyed. >+ */ >+ fput(file); >+ return 0; >+ >+err: >+ fput(file); >+ return -EINVAL; The cleanup, i.e., filemap_invalidate_unlock() and fput(), is common. So, I think it may be slightly better to consolidate the common part e.g., int ret = -EINVAL; ... xa_store_range(&gmem->bindings, start, end - 1, slot, GFP_KERNEL); ret = 0; unlock: filemap_invalidate_unlock(inode->i_mapping); err: /* * Drop the reference to the file, even on success. The file pins KVM, * not the other way 'round. Active bindings are invalidated if the * file is closed before memslots are destroyed. */ fput(file); return ret;