static int binder_thread_read(struct binder_proc *proc,
			      struct binder_thread *thread,
			      binder_uintptr_t binder_buffer, size_t size,
			      binder_size_t *consumed, int non_block)
{
	void __user *buffer = (void __user *)(uintptr_t)binder_buffer;
	void __user *ptr = buffer + *consumed;
	void __user *end = buffer + size;

	int ret = 0;
	int wait_for_proc_work;

	if (*consumed == 0) {
		if (put_user(BR_NOOP, (uint32_t __user *)ptr))
			return -EFAULT;
		ptr += sizeof(uint32_t);
	}

retry:
	binder_inner_proc_lock(proc);
	wait_for_proc_work = binder_available_for_proc_work_ilocked(thread);
	binder_inner_proc_unlock(proc);

	thread->looper |= BINDER_LOOPER_STATE_WAITING;

	trace_binder_wait_for_work(wait_for_proc_work,
				   !!thread->transaction_stack,
				   !binder_worklist_empty(proc, &thread->todo));
	if (wait_for_proc_work) {
		if (!(thread->looper & (BINDER_LOOPER_STATE_REGISTERED |
					BINDER_LOOPER_STATE_ENTERED))) {
			binder_user_error("%d:%d ERROR: Thread waiting for process work before calling BC_REGISTER_LOOPER or BC_ENTER_LOOPER (state %x)\n",
				proc->pid, thread->pid, thread->looper);
			wait_event_interruptible(binder_user_error_wait,
						 binder_stop_on_user_error < 2);
		}
		binder_set_nice(proc->default_priority);
	}

	if (non_block) {
		if (!binder_has_work(thread, wait_for_proc_work))
			ret = -EAGAIN;
	} else {
		ret = binder_wait_for_work(thread, wait_for_proc_work);
	}

	thread->looper &= ~BINDER_LOOPER_STATE_WAITING;

	if (ret)
		return ret;

	while (1) {
		uint32_t cmd;
		struct binder_transaction_data tr;
		struct binder_work *w = NULL;
		struct list_head *list = NULL;
		struct binder_transaction *t = NULL;
		struct binder_thread *t_from;

		binder_inner_proc_lock(proc);
		if (!binder_worklist_empty_ilocked(&thread->todo))
			list = &thread->todo;
		else if (!binder_worklist_empty_ilocked(&proc->todo) &&
			   wait_for_proc_work)
			list = &proc->todo;
		else {
			binder_inner_proc_unlock(proc);

			/* no data added */
			if (ptr - buffer == 4 && !thread->looper_need_return)
				goto retry;
			break;
		}

		if (end - ptr < sizeof(tr) + 4) {
			binder_inner_proc_unlock(proc);
			break;
		}
		w = binder_dequeue_work_head_ilocked(list);
		if (binder_worklist_empty_ilocked(&thread->todo))
			thread->process_todo = false;

		switch (w->type) {
		case BINDER_WORK_TRANSACTION: {
			binder_inner_proc_unlock(proc);
			t = container_of(w, struct binder_transaction, work);
		} break;
		case BINDER_WORK_RETURN_ERROR: {
			struct binder_error *e = container_of(
					w, struct binder_error, work);

			WARN_ON(e->cmd == BR_OK);
			binder_inner_proc_unlock(proc);
			if (put_user(e->cmd, (uint32_t __user *)ptr))
				return -EFAULT;
			e->cmd = BR_OK;
			ptr += sizeof(uint32_t);

			binder_stat_br(proc, thread, e->cmd);
		} break;
		case BINDER_WORK_TRANSACTION_COMPLETE: {
			binder_inner_proc_unlock(proc);
			cmd = BR_TRANSACTION_COMPLETE;
			if (put_user(cmd, (uint32_t __user *)ptr))
				return -EFAULT;
			ptr += sizeof(uint32_t);

			binder_stat_br(proc, thread, cmd);
			binder_debug(BINDER_DEBUG_TRANSACTION_COMPLETE,
				     "%d:%d BR_TRANSACTION_COMPLETE\n",
				     proc->pid, thread->pid);
			kfree(w);
			binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
		} break;
		case BINDER_WORK_NODE: {
			struct binder_node *node = container_of(w, struct binder_node, work);
			int strong, weak;
			binder_uintptr_t node_ptr = node->ptr;
			binder_uintptr_t node_cookie = node->cookie;
			int node_debug_id = node->debug_id;
			int has_weak_ref;
			int has_strong_ref;
			void __user *orig_ptr = ptr;

			BUG_ON(proc != node->proc);
			strong = node->internal_strong_refs ||
					node->local_strong_refs;
			weak = !hlist_empty(&node->refs) ||
					node->local_weak_refs ||
					node->tmp_refs || strong;
			has_strong_ref = node->has_strong_ref;
			has_weak_ref = node->has_weak_ref;

			if (weak && !has_weak_ref) {
				node->has_weak_ref = 1;
				node->pending_weak_ref = 1;
				node->local_weak_refs++;
			}
			if (strong && !has_strong_ref) {
				node->has_strong_ref = 1;
				node->pending_strong_ref = 1;
				node->local_strong_refs++;
			}
			if (!strong && has_strong_ref)
				node->has_strong_ref = 0;
			if (!weak && has_weak_ref)
				node->has_weak_ref = 0;
			if (!weak && !strong) {
				binder_debug(BINDER_DEBUG_INTERNAL_REFS,
					     "%d:%d node %d u%016llx c%016llx deleted\n",
					     proc->pid, thread->pid,
					     node_debug_id,
					     (u64)node_ptr,
					     (u64)node_cookie);
				rb_erase(&node->rb_node, &proc->nodes);
				binder_inner_proc_unlock(proc);
				binder_node_lock(node);
				/*
				 * Acquire the node lock before freeing the
				 * node to serialize with other threads that
				 * may have been holding the node lock while
				 * decrementing this node (avoids race where
				 * this thread frees while the other thread
				 * is unlocking the node after the final
				 * decrement)
				 */
				binder_node_unlock(node);
				binder_free_node(node);
			} else
				binder_inner_proc_unlock(proc);

			if (weak && !has_weak_ref)
				ret = binder_put_node_cmd(
						proc, thread, &ptr, node_ptr,
						node_cookie, node_debug_id,
						BR_INCREFS, "BR_INCREFS");
			if (!ret && strong && !has_strong_ref)
				ret = binder_put_node_cmd(
						proc, thread, &ptr, node_ptr,
						node_cookie, node_debug_id,
						BR_ACQUIRE, "BR_ACQUIRE");
			if (!ret && !strong && has_strong_ref)
				ret = binder_put_node_cmd(
						proc, thread, &ptr, node_ptr,
						node_cookie, node_debug_id,
						BR_RELEASE, "BR_RELEASE");
			if (!ret && !weak && has_weak_ref)
				ret = binder_put_node_cmd(
						proc, thread, &ptr, node_ptr,
						node_cookie, node_debug_id,
						BR_DECREFS, "BR_DECREFS");
			if (orig_ptr == ptr)
				binder_debug(BINDER_DEBUG_INTERNAL_REFS,
					     "%d:%d node %d u%016llx c%016llx state unchanged\n",
					     proc->pid, thread->pid,
					     node_debug_id,
					     (u64)node_ptr,
					     (u64)node_cookie);
			if (ret)
				return ret;
		} break;
		case BINDER_WORK_DEAD_BINDER:
		case BINDER_WORK_DEAD_BINDER_AND_CLEAR:
		case BINDER_WORK_CLEAR_DEATH_NOTIFICATION: {
			struct binder_ref_death *death;
			uint32_t cmd;
			binder_uintptr_t cookie;

			death = container_of(w, struct binder_ref_death, work);
			if (w->type == BINDER_WORK_CLEAR_DEATH_NOTIFICATION)
				cmd = BR_CLEAR_DEATH_NOTIFICATION_DONE;
			else
				cmd = BR_DEAD_BINDER;
			cookie = death->cookie;

			binder_debug(BINDER_DEBUG_DEATH_NOTIFICATION,
				     "%d:%d %s %016llx\n",
				      proc->pid, thread->pid,
				      cmd == BR_DEAD_BINDER ?
				      "BR_DEAD_BINDER" :
				      "BR_CLEAR_DEATH_NOTIFICATION_DONE",
				      (u64)cookie);
			if (w->type == BINDER_WORK_CLEAR_DEATH_NOTIFICATION) {
				binder_inner_proc_unlock(proc);
				kfree(death);
				binder_stats_deleted(BINDER_STAT_DEATH);
			} else {
				binder_enqueue_work_ilocked(
						w, &proc->delivered_death);
				binder_inner_proc_unlock(proc);
			}
			if (put_user(cmd, (uint32_t __user *)ptr))
				return -EFAULT;
			ptr += sizeof(uint32_t);
			if (put_user(cookie,
				     (binder_uintptr_t __user *)ptr))
				return -EFAULT;
			ptr += sizeof(binder_uintptr_t);
			binder_stat_br(proc, thread, cmd);
			if (cmd == BR_DEAD_BINDER)
				goto done; /* DEAD_BINDER notifications can cause transactions */
		} break;
		}

		if (!t)
			continue;

		BUG_ON(t->buffer == NULL);
		if (t->buffer->target_node) {
			struct binder_node *target_node = t->buffer->target_node;

			tr.target.ptr = target_node->ptr;
			tr.cookie =  target_node->cookie;
			t->saved_priority = task_nice(current);
			if (t->priority < target_node->min_priority &&
			    !(t->flags & TF_ONE_WAY))
				binder_set_nice(t->priority);
			else if (!(t->flags & TF_ONE_WAY) ||
				 t->saved_priority > target_node->min_priority)
				binder_set_nice(target_node->min_priority);
			cmd = BR_TRANSACTION;
		} else {
			tr.target.ptr = 0;
			tr.cookie = 0;
			cmd = BR_REPLY;
		}
		tr.code = t->code;
		tr.flags = t->flags;
		tr.sender_euid = from_kuid(current_user_ns(), t->sender_euid);

		t_from = binder_get_txn_from(t);
		if (t_from) {
			struct task_struct *sender = t_from->proc->tsk;

			tr.sender_pid = task_tgid_nr_ns(sender,
							task_active_pid_ns(current));
		} else {
			tr.sender_pid = 0;
		}

		tr.data_size = t->buffer->data_size;
		tr.offsets_size = t->buffer->offsets_size;
		tr.data.ptr.buffer = (binder_uintptr_t)
			((uintptr_t)t->buffer->data +
			binder_alloc_get_user_buffer_offset(&proc->alloc));
		tr.data.ptr.offsets = tr.data.ptr.buffer +
					ALIGN(t->buffer->data_size,
					    sizeof(void *));

		if (put_user(cmd, (uint32_t __user *)ptr)) {
			if (t_from)
				binder_thread_dec_tmpref(t_from);

			binder_cleanup_transaction(t, "put_user failed",
						   BR_FAILED_REPLY);

			return -EFAULT;
		}
		ptr += sizeof(uint32_t);
		if (copy_to_user(ptr, &tr, sizeof(tr))) {
			if (t_from)
				binder_thread_dec_tmpref(t_from);

			binder_cleanup_transaction(t, "copy_to_user failed",
						   BR_FAILED_REPLY);

			return -EFAULT;
		}
		ptr += sizeof(tr);

		trace_binder_transaction_received(t);
		binder_stat_br(proc, thread, cmd);
		binder_debug(BINDER_DEBUG_TRANSACTION,
			     "%d:%d %s %d %d:%d, cmd %d size %zd-%zd ptr %016llx-%016llx\n",
			     proc->pid, thread->pid,
			     (cmd == BR_TRANSACTION) ? "BR_TRANSACTION" :
			     "BR_REPLY",
			     t->debug_id, t_from ? t_from->proc->pid : 0,
			     t_from ? t_from->pid : 0, cmd,
			     t->buffer->data_size, t->buffer->offsets_size,
			     (u64)tr.data.ptr.buffer, (u64)tr.data.ptr.offsets);

		if (t_from)
			binder_thread_dec_tmpref(t_from);
		t->buffer->allow_user_free = 1;
		if (cmd == BR_TRANSACTION && !(t->flags & TF_ONE_WAY)) {
			binder_inner_proc_lock(thread->proc);
			t->to_parent = thread->transaction_stack;
			t->to_thread = thread;
			thread->transaction_stack = t;
			binder_inner_proc_unlock(thread->proc);
		} else {
			binder_free_transaction(t);
		}
		break;
	}

done:

	*consumed = ptr - buffer;
	binder_inner_proc_lock(proc);
	if (proc->requested_threads == 0 &&
	    list_empty(&thread->proc->waiting_threads) &&
	    proc->requested_threads_started < proc->max_threads &&
	    (thread->looper & (BINDER_LOOPER_STATE_REGISTERED |
	     BINDER_LOOPER_STATE_ENTERED)) /* the user-space code fails to */
	     /*spawn a new thread if we leave this out */) {
		proc->requested_threads++;
		binder_inner_proc_unlock(proc);
		binder_debug(BINDER_DEBUG_THREADS,
			     "%d:%d BR_SPAWN_LOOPER\n",
			     proc->pid, thread->pid);
		if (put_user(BR_SPAWN_LOOPER, (uint32_t __user *)buffer))
			return -EFAULT;
		binder_stat_br(proc, thread, BR_SPAWN_LOOPER);
	} else
		binder_inner_proc_unlock(proc);
	return 0;
}
Unknown