net: wwan: t7xx: Add control port

Dear Dan,
Thanks!

Dear Ricardo,
May we help to check the Smatch checker warning?
Seems also happened on DMA/Data path HW patch~

BR
Haijun

-----Original Message-----
From: Dan Carpenter <[email protected]>
Sent: Tuesday, May 17, 2022 7:50 PM
To: Haijun Liu (刘海军) <[email protected]>
Cc: [email protected]
Subject: [bug report] net: wwan: t7xx: Add control port

Hello Haijun Liu,

The patch da45d2566a1d: "net: wwan: t7xx: Add control port" from May 6, 2022, leads to the following Smatch static checker warning:

drivers/net/wwan/t7xx/t7xx_modem_ops.c:499 t7xx_core_hk_handler()
error: potentially dereferencing uninitialized 'event'.

drivers/net/wwan/t7xx/t7xx_modem_ops.c

     457 static void t7xx_core_hk_handler(struct t7xx_modem *md, struct t7xx_fsm_ctl *ctl,
     458                                  enum t7xx_fsm_event_state event_id,
     459                                  enum t7xx_fsm_event_state err_detect)
     460 {
     461         struct t7xx_sys_info *core_info = &md->core_md;
     462         struct device *dev = &md->t7xx_dev->pdev->dev;
     463         struct t7xx_fsm_event *event, *event_next;
                                        ^^^^^


     464         unsigned long flags;
     465         int ret;
     466
     467         t7xx_prepare_host_rt_data_query(core_info);
     468
     469         while (!kthread_should_stop()) {
                         ^^^^^^^^^^^^^^^^^^^^^ What about this is true on the first iteration through the loop?

     470                 bool event_received = false;
     471
     472                 spin_lock_irqsave(&ctl->event_lock, flags);
     473                 list_for_each_entry_safe(event, event_next, &ctl->event_queue, entry) {
     474                         if (event->event_id == err_detect) {
     475                                 list_del(&event->entry);
     476                                 spin_unlock_irqrestore(&ctl->event_lock, flags);
     477                                 dev_err(dev, "Core handshake error event received\n");
     478                                 goto err_free_event;
     479                         } else if (event->event_id == event_id) {
     480                                 list_del(&event->entry);
     481                                 event_received = true;
     482                                 break;
     483                         }
     484                 }
     485                 spin_unlock_irqrestore(&ctl->event_lock, flags);
     486
     487                 if (event_received)
     488                         break;
     489
     490                 wait_event_interruptible(ctl->event_wq, !list_empty(&ctl->event_queue) ||
     491                                          kthread_should_stop());
     492                 if (kthread_should_stop())
     493                         goto err_free_event;
     494         }
     495
     496         if (ctl->exp_flg)
     497                 goto err_free_event;
                         ^^^^^^^^^^^^^^^^^^^ Uninitialized on this path too.

     498
--> 499         ret = t7xx_parse_host_rt_data(ctl, core_info, dev, event->data, event->length);
                                                                    ^^^^^^^ Uninitialized?

     500         if (ret) {
     501                 dev_err(dev, "Host failure parsing runtime data: %d\n", ret);
     502                 goto err_free_event;
     503         }
     504
     505         if (ctl->exp_flg)
     506                 goto err_free_event;
     507
     508         ret = t7xx_prepare_device_rt_data(core_info, dev, event->data);
     509         if (ret) {
     510                 dev_err(dev, "Device failure parsing runtime data: %d", ret);
     511                 goto err_free_event;
     512         }
     513
     514         core_info->ready = true;
     515         core_info->handshake_ongoing = false;
     516         wake_up(&ctl->async_hk_wq);
     517 err_free_event:
     518         kfree(event);
     519 }

regards,
dan carpenter

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