Re: [PATCH] xnthread_relax: Make sure wakework irq work has a stack

[Richard Weinberger <richard@nod.at>]

----- Ursprüngliche Mail -----
>> How about additionally widening the suspected race window by adding a
>> delay to lostage_task_wakeup?
> 
> Excellent idea! :-)

Yeah, with a dealy in lostage_task_wakeup() my WARN_ON_ONCE() triggers
very quickly.

[  123.237698] ------------[ cut here ]------------
[  123.238755] WARNING: CPU: 1 PID: 1411 at kernel/xenomai/thread.c:2158 xnthread_relax+0x5d4/0x680
[  123.240698] Modules linked in: loader(OE) tun bridge stp llc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv6 nft_reject nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables xeno_can_peak_pci xeno_can_sja1000 xeno_can xeno_16550A libcrc32c nfnetlink xeno_rtipc snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device snd_pcm snd_timer snd soundcore sunrpc pktcdvd rt_e1000 rt_e1000_new crc32_pclmul rtnet i2c_piix4 bochs drm_vram_helper drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec drm_ttm_helper ttm drm e1000 serio_raw crc32c_intel ata_generic pata_acpi floppy qemu_fw_cfg fuse
[  123.252790] CPU: 1 PID: 1411 Comm: app Tainted: G           OE     5.15.9xeno3.2-x8664G-rw #6
[  123.255001] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
[  123.257443] IRQ stage: Linux
[  123.258090] RIP: 0010:xnthread_relax+0x5d4/0x680
[  123.259136] Code: 18 05 00 00 e8 5d 8d 13 00 41 8b 97 18 05 00 00 48 8d b3 6c 02 00 00 48 c7 c7 a0 8f 6d 82 e8 5c 96 cc 00 0f 0b e9 9d fc ff ff <0f> 0b e9 af fd ff ff 65 44 8b 2d a5 2d ca 7e 41 83 fd 03 77 7a 45
[  123.263163] RSP: 0018:ffff88811381fb60 EFLAGS: 00010202
[  123.264330] RAX: 0000000000000022 RBX: ffffc90000bf6408 RCX: ffffffff8137e13b
[  123.265893] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88811381fc18
[  123.267474] RBP: 1ffff11022703f6e R08: ffffed1022703f84 R09: ffffed1022703f84
[  123.269095] R10: ffff88811381fc1b R11: ffffed1022703f83 R12: ffff88811381fc10
[  123.270662] R13: ffff888104f03e00 R14: 0000000000000000 R15: ffffc90000bf6428
[  123.272222] FS:  00007fb4d0aca700(0000) GS:ffff88811b080000(0000) knlGS:0000000000000000
[  123.273983] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  123.275262] CR2: 0000000000a74008 CR3: 0000000111938003 CR4: 0000000000170ea0
[  123.276823] Call Trace:
[  123.277401]  <TASK>
[  123.277878]  ? xnthread_wait_period+0x4c0/0x4c0
[  123.278899]  ? xnsynch_release+0x690/0x690
[  123.279828]  ? __cobalt_sem_destroy+0x2dd/0x630
[  123.280848]  ? recalibrate_cpu_khz+0x10/0x10
[  123.281812]  ? xnthread_set_periodic+0x3a0/0x3a0
[  123.282855]  ? recalibrate_cpu_khz+0x10/0x10
[  123.283816]  ? ktime_get_mono_fast_ns+0xdb/0x120
[  123.284852]  ? xnlock_dbg_release+0xd9/0x170
[  123.285812]  prepare_for_signal+0x297/0x3a0
[  123.286765]  ? CoBaLt_serialdbg+0x140/0x140
[  123.287709]  ? cobalt_thread_setschedparam_ex+0x1a0/0x1a0
[  123.288906]  handle_head_syscall+0x6e2/0x810
[  123.289867]  ? __cobalt_cond_wait_prologue+0xf60/0xf60
[  123.291017]  ? CoBaLt_trace+0x650/0x650
[  123.291887]  ? cobalt_thread_setschedparam_ex+0x1a0/0x1a0
[  123.293088]  pipeline_syscall+0x8e/0x140
[  123.293979]  syscall_enter_from_user_mode+0x30/0x80
[  123.295076]  do_syscall_64+0x1d/0xa0
[  123.295895]  entry_SYSCALL_64_after_hwframe+0x44/0xae

Thanks,
//richard