From: Miroslav Lichvar <mlichvar@redhat.com>
To: intel-wired-lan@lists.osuosl.org
Cc: Richard Cochran <richardcochran@gmail.com>
Subject: [Intel-wired-lan] ice driver bug with PTP vclocks
Date: Wed, 9 Nov 2022 16:20:02 +0100 [thread overview]
Message-ID: <Y2vFIq/6rB7k12Gd@localhost> (raw)
It seems the locking of the PTP clock in the ice driver conflicts with
spinlocks used by PTP virtual clocks protecting their timecounter and
cyclecounter. I get the following report when running ptp4l+phc2sys
pairs on multiple ports of an E810 with vclocks enabled:
BUG: scheduling while atomic: ptp7/3859/0x00000002
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 PID: 3859 Comm: ptp7 Tainted: G W 6.0.6-300.fc37.x86_64 #1
Call Trace:
<TASK>
dump_stack_lvl+0x44/0x5c
__schedule_bug.cold+0x81/0x8e
__schedule+0xe82/0x12b0
? get_nohz_timer_target+0x18/0x1a0
? timerqueue_add+0x62/0xb0
? enqueue_hrtimer+0x2f/0x80
schedule+0x5d/0xe0
schedule_hrtimeout_range_clock+0xb5/0x100
? __hrtimer_init+0xe0/0xe0
usleep_range_state+0x50/0x70
ice_ptp_lock+0x39/0x60 [ice]
ice_ptp_gettimex64+0x31/0x70 [ice]
? ptp_clock_release+0x50/0x50
? kthread_stop+0x170/0x170
ptp_vclock_read+0x37/0x90
timecounter_read+0x14/0x60
ptp_vclock_refresh+0x2a/0x50
ptp_aux_kworker+0x1c/0x40
kthread_worker_fn+0xaa/0x250
kthread+0xe9/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x22/0x30
</TASK>
I tried to fix this in the vclock code by moving the PHC read outside
of the spinlock, but it turns out that's not a complete fix and it
breaks the update of the timecounter's cycle_last value. I suspect I'd
need to modify the cyclecounter to use a cached value which would need
to be read ahead of the timecounter call.
Any chance this could be addressed in the ice driver? Any suggestions?
--
Miroslav Lichvar
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next reply other threads:[~2022-11-09 15:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-09 15:20 Miroslav Lichvar [this message]
2022-11-09 20:08 ` [Intel-wired-lan] ice driver bug with PTP vclocks Keller, Jacob E
2023-02-02 20:43 ` Jacob Keller
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