Slow path detected in RTCAP

François Legal devel at
Tue Mar 24 17:05:33 CET 2020


I'm trying to port an old application that used to be running on DSPBIOS to Xenomai, using RTNET for the network part.
I'm getting some weird results with semaphores, but before that I got that debug dump :

[   49.201310] WARNING: CPU: 0 PID: 958 at /home/dev/UCC/linux-4.4.189/kernel/ipipe/core.c:1912 __ipipe_post_work_root+0xe8/0xfc()
[   49.214809] CPU: 0 PID: 958 Comm: Maître de Rés Not tainted 4.4.189 #47
[   49.222636] Hardware name: Xilinx Zynq Platform
[   49.227791] I-pipe domain: Xenomai
[   49.231705] [<c00159e8>] (unwind_backtrace) from [<c0012e24>] (show_stack+0x10/0x14)
[   49.240511] [<c0012e24>] (show_stack) from [<c0222798>] (dump_stack+0x104/0x120)
[   49.248887] [<c0222798>] (dump_stack) from [<c0025568>] (warn_slowpath_common+0x80/0xb0)
[   49.258162] [<c0025568>] (warn_slowpath_common) from [<c0025660>] (warn_slowpath_null+0x1c/0x24)
[   49.268172] [<c0025660>] (warn_slowpath_null) from [<c008b7bc>] (__ipipe_post_work_root+0xe8/0xfc)
[   49.278344] [<c008b7bc>] (__ipipe_post_work_root) from [<c00a4df0>] (rtdm_nrtsig_pend+0x24/0x2c)
[   49.288219] [<c00a4df0>] (rtdm_nrtsig_pend) from [<c034e2c8>] (rtcap_xmit_hook+0x150/0x1bc)
[   49.297550] [<c034e2c8>] (rtcap_xmit_hook) from [<c033fc64>] (rtdev_locked_xmit+0x28/0x3c)
[   49.307010] [<c033fc64>] (rtdev_locked_xmit) from [<c0340be4>] (rtdev_xmit+0x38/0x84)
[   49.315871] [<c0340be4>] (rtdev_xmit) from [<c034935c>] (rt_packet_sendmsg+0x2d4/0x304)
[   49.324865] [<c034935c>] (rt_packet_sendmsg) from [<c00a6380>] (rtdm_fd_sendmsg+0x80/0x98)
[   49.334205] [<c00a6380>] (rtdm_fd_sendmsg) from [<c00aa0d8>] (CoBaLt_sendmsg+0x78/0xa4)
[   49.343275] [<c00aa0d8>] (CoBaLt_sendmsg) from [<c00b602c>] (handle_head_syscall+0x168/0x320)
[   49.352953] [<c00b602c>] (handle_head_syscall) from [<c000f9d0>] (local_restart+0x20/0x44)

The indicated thread "Maître de Rés" is a xenomai posix thread.

I see that the call stack includes RTCAP code, and I checked that this does not happen when RTCAP is disabled in kernel build. Anyway, Is this slow path to be expected in RTCAP ?



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