calling bt_gatt_notify() from preemptible thread

[Ronvanl]

Hi all,

Im struggling with the following problem. I'm testing a bluetooth connection throughput by continuously sending data as in the code snippet. However the code is asserting in l2cap layer after some seconds or even minutes. This only seems to happen when I call the bluetooth notify from a preemptible thread (e.g main thread). However, if I run it from a cooperative thread I haven't seen the assert yet.

Wondering if the Bluetooth functions need to be called from cooperative threads only. (btw testing on zephyr v4.1.0 )

 while (true) {
    int res = bt_gatt_notify(conn, &my_svc.attrs[1], data, sizeof(data));
  }

00> ASSERTION FAIL [old] @ WEST_TOPDIR/zephyr/subsys/bluetooth/host/l2cap.c:719
00> [00:03:10.396,000] os: r0/a1: 0x00000004 r1/a2: 0x000002cf r2/a3: 0x0000001d[0m
00> [00:03:10.397,000] os: r3/a4: 0x00000004 r12/ip: 0xa0000000 r14/lr: 0x0000a219
00> [00:03:10.397,000] os: xpsr: 0x21000000
00> [00:03:10.397,000] os: Faulting instruction address (r15/pc): 0x000194bc
00> [00:03:10.398,000] os: >>> ZEPHYR FATAL ERROR 4: Kernel panic on CPU 0
00> [00:03:10.398,000] os: Current thread: 0x10003598 (sysworkq)
00> [00:03:11.075,000] os: Halting system

[hermabe]

This looks like a bug to me. As far as I know there is no requirement to call bluetooth apis from a cooperative thread.

[hermabe]

Moved to #89705