On Wed, 21 Feb 2024 15:38:47 +0100, Hans Verkuil wrote:
> > After unlocking adap->lock in cec_claim_log_addrs(), cec_claim_log_addrs() may
> > re-enter, causing this issue to occur.
>
> But if it is called again, then it should hit this at the start of the function:
>
> if (WARN_ON(adap->is_configuring || adap->is_configured))
> return;
>
> I'm still not sure what causes the KASAN hung task since I cannot seem to reproduce
> it, and because it is hard for me to find enough time to dig into this.
Please pay attention to the following section of code in cec_config_thread_func():
3 unconfigure:
2 for (i = 0; i < las->num_log_addrs; i++)
1 las->log_addr[i] = CEC_LOG_ADDR_INVALID;
1573 cec_adap_unconfigure(adap); // [1], is_configured = false;
1 adap->is_configuring = false; // [2], is_configuring = false;
2 adap->must_reconfigure = false;
3 adap->kthread_config = NULL;
4 complete(&adap->config_completion);
5 mutex_unlock(&adap->lock); // [3], Afterwards
And the following code is included in cec_claim_log-addrs():
3 } else if (block) {
2 mutex_unlock(&adap->lock);
1 wait_for_completion(&adap->config_completion);
1607 mutex_lock(&adap->lock); // [4], During the period before re obtaining the adap->lock, how did cec_claim_log-addrs() re-enter?
BR,
edward
