From: Mike Galbraith <efault@gmx.de>
To: RT <linux-rt-users@vger.kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [patch] Re: v5.15-rc2-rt3: WARNING: CPU: 0 PID: 12 at ./include/linux/seqlock.h:271
Date: Sun, 26 Sep 2021 06:05:05 +0200 [thread overview]
Message-ID: <a105fecc71d4b721d4e025e2caf2b13336b5d0fc.camel@gmx.de> (raw)
In-Reply-To: <e903e245a501d230e90e32d00460ec0d19cc8878.camel@gmx.de>
On Fri, 2021-09-24 at 07:22 +0200, Mike Galbraith wrote:
> Greetings,
>
> I met this lockdep_assert_preemption_disabled() gripe when starting
> ltp zram tests.
Before actually, I just wasn't paying attention.
<snip gripe>
net: bridge: mcast: Disable preemption in br_multicast_update_querier() for RT
write_seqcount_begin() in br_multicast_update_querier() complains about
preemption not being disabled during RT softirq processesing. Since the
read side spins, disable preemption across the tiny write side for RT.
Signed-off-by: Mike Galbraith <efault@gmx.de>
---
net/bridge/br_multicast.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1679,10 +1679,14 @@ static void br_multicast_update_querier(
{
lockdep_assert_held_once(&brmctx->br->multicast_lock);
+ if (IS_ENABLED(CONFIG_PREEMPT_RT))
+ preempt_disable();
write_seqcount_begin(&querier->seq);
querier->port_ifidx = ifindex;
memcpy(&querier->addr, saddr, sizeof(*saddr));
write_seqcount_end(&querier->seq);
+ if (IS_ENABLED(CONFIG_PREEMPT_RT))
+ preempt_enable();
}
static void br_multicast_send_query(struct net_bridge_mcast *brmctx,
next prev parent reply other threads:[~2021-09-26 4:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 21:00 [ANNOUNCE] v5.15-rc2-rt3 Sebastian Andrzej Siewior
2021-09-24 5:22 ` v5.15-rc2-rt3: WARNING: CPU: 0 PID: 12 at ./include/linux/seqlock.h:271 Mike Galbraith
2021-09-26 4:05 ` Mike Galbraith [this message]
2021-09-26 15:10 ` [patch] " Thomas Gleixner
2021-09-27 3:19 ` Mike Galbraith
2021-09-27 8:13 ` [PATCH] net: bridge: mcast: Associate the seqcount with its protecting lock Sebastian Andrzej Siewior
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