linux-kernel - Re: [hrtimer] 336a9cde10: WARNING:at_kernel/time/hrtimer.c:#hrtimer

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Date:   Mon, 20 Feb 2017 09:26:53 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     kernel test robot <xiaolong.ye@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Tomasz Nowicki <tn@...ihalf.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, tipbuild@...or.com, lkp@...org
Subject: Re: [hrtimer] 336a9cde10:
 WARNING:at_kernel/time/hrtimer.c:#hrtimer_init

On 19/02/17 21:06, kernel test robot wrote:
> 
> FYI, we noticed the following commit:
> 
> commit: 336a9cde10d641e70bac67d90ae91b3190c3edca ("hrtimer: Catch invalid clockids again")
> https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git timers/core
> 
> in testcase: boot
> 
> on test machine: qemu-system-x86_64 -enable-kvm -cpu host -smp 2 -m 4G
> 
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):

This is indeed the expected effect: mac80211_hwsim is using an illegal
clockid, and we're letting the world now about it. The obvious
workaround is the following patch:

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 1620a5d2757d..0889fc81ce9e 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -2671,7 +2671,7 @@ static int mac80211_hwsim_new_radio(struct genl_info *info,
 
 	tasklet_hrtimer_init(&data->beacon_timer,
 			     mac80211_hwsim_beacon,
-			     CLOCK_MONOTONIC_RAW, HRTIMER_MODE_ABS);
+			     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 
 	spin_lock_bh(&hwsim_radio_lock);
 	list_add_tail(&data->list, &hwsim_radios);

which suppresses the warning and preserves the current behaviour,
but doesn't provide what the author expected (the kernel never
pretended to support CLOCK_MONOTONIC_RAW though).

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...