nrf52 telnet_shell panic. Mutex using in ISR.

[ToJIka4]

Stack is

#0  assert_post_action (file=file@entry=0x4ab31 "ZEPHYR_BASE/kernel/include/ksched.h", line=line@entry=269) at ZEPHYR_BASE/lib/os/assert.c:45
#1  0x0003086a in z_sched_lock () at ZEPHYR_BASE/kernel/include/ksched.h:269
#2  z_impl_k_mutex_unlock (mutex=mutex@entry=0x200023d8 <contexts+248>) at ZEPHYR_BASE/kernel/mutex.c:232
#3  0x0003c556 in k_mutex_unlock (mutex=mutex@entry=0x200023d8 <contexts+248>) at zephyr/include/generated/syscalls/kernel.h:644
#4  0x0003c692 in net_context_send (context=0x200023d0 <contexts+240>, buf=0x20000938 <shell_transport_telnet_shell_telnet+8>, len=13, cb=cb@entry=0x5399 <telnet_sent_cb>, timeout=timeout@entry=-1, user_data=user_data@entry=0x0 <sys_pm_notify_power_state_entry>) at ZEPHYR_BASE/subsys/net/ip/net_context.c:1668
#5  0x0000525e in telnet_send () at ZEPHYR_BASE/subsys/shell/shell_telnet.c:138
#6  0x00032eea in z_timer_expiration_handler (t=0x200009a4 <shell_transport_telnet_shell_telnet+116>) at ZEPHYR_BASE/kernel/timer.c:65
#7  0x00032dc4 in z_clock_announce (ticks=<optimized out>) at ZEPHYR_BASE/kernel/timeout.c:204
#8  0x00007dee in _isr_wrapper () at ZEPHYR_BASE/arch/arm/core/aarch32/isr_wrapper.S:163
#9  <signal handler called>

Since timer handlers in nrf52 is in ISR and network uses mutexes we got panic. Maybe moving telnet_send in separate thread will resolve this issue.

[rlubos]

Reproduced with telnet sample running over BLE IPSP. I'll try to put telnet_send on a system workqueue instead of calling it directly from a timer handler. If it solves the issue I'll come up with a PR.

[ToJIka4]

Fast solution. Works for me.

--- a/subsys/shell/shell_telnet.c
+++ b/subsys/shell/shell_telnet.c
@@ -150,7 +150,15 @@ static int telnet_send(void)
        return 0;
 }

+static struct k_work send_work;
+
 static void telnet_send_prematurely(struct k_timer *timer)
+{
+       //(void)telnet_send();
+       k_work_submit(&send_work);
+}
+
+static void telnet_send_work(struct k_work *work)
 {
        (void)telnet_send();
 }
@@ -344,6 +352,8 @@ static int init(const struct shell_transport *transport,

        k_fifo_init(&sh_telnet->rx_fifo);
        k_timer_init(&sh_telnet->send_timer, telnet_send_prematurely, NULL);
+
+       k_work_init(&send_work, telnet_send_work);

        return 0;
 }

[rlubos]

Yeah, I've originally thought of something similar, but eventually, I've ended up using a k_delayed_work. Will submit a PR.