Bluetooth: split: 'e' assert during disconnect

[paulgavrikov]

Describe the bug
When using the Split LL with Zephyr we occasionally observe crashes during different operations on master or slave side. Upon closer observation it looks like these asserts happen after a disconnect packet was sent. Reducing the maximum number of supported connecations does not fix this. Switching back to the legacy LL resolves this.

To Reproduce
Our ZTests connect to a peripheral and typically perform a couple of actions (e.g. GATT ops, pairing, L2CAP etc.). Then we disconnect and run the next test. I haven't found one specific test that always fails as the asserts appear to be happen randomly.

Expected behavior
The stack should not crash.

Impact
showstopper

Screenshots or console output

[20:56:06:560] assert: 'e' failed␍␊
[20:56:06:571] [00:01:49.082,061] <0x1b>[1;31m<err> os: r0/a1: 0x00000003 r1/a2: 0x0000000a r2/a3: 0x00000001<0x1b>[0m␍␊
[20:56:06:571] [00:01:49.090,759] <0x1b>[1;31m<err> os: r3/a4: 0x0002e963 r12/ip: 0x00000008 r14/lr: 0x000197ef<0x1b>[0m␍␊
[20:56:06:579] [00:01:49.099,456] <0x1b>[1;31m<err> os: xpsr: 0x61000011<0x1b>[0m␍␊
[20:56:06:594] [00:01:49.104,705] <0x1b>[1;31m<err> os: Faulting instruction address (r15/pc): 0x000197fa<0x1b>[0m␍␊
[20:56:06:594] [00:01:49.112,609] <0x1b>[1;31m<err> os: >>> ZEPHYR FATAL ERROR 3: Kernel oops<0x1b>[0m␍␊
[20:56:06:600] [00:01:49.119,476] <0x1b>[1;31m<err> os: Current thread: 0x20001200 (BT ECC)<0x1b>[0m␍␊
[20:56:06:609] [00:01:49.126,190] <0x1b>[1;31m<err> os: Halting system<0x1b>[0m␍␊

Environment (please complete the following information):

• OS: (e.g. Linux, MacOS, Windows): Kubuntu 18.04
• Toolchain (e.g Zephyr SDK, ...): Zephyr SDK 0.10.3
• Commit SHA or Version used: 2051ad1

Additional context

[cvinayak]

@paulgavrikov please verify using #19469.

[paulgavrikov]

@cvinayak yes, that works. I see a bunch of "D: " logs now but not asserts. Thanks!