From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Guillaume Morin <guillaume@morinfr.org>,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH 5.4 02/11] rcu: Tighten rcu_advance_cbs_nowake() checks
Date: Thu, 27 Jan 2022 19:09:03 +0100 [thread overview]
Message-ID: <20220127180258.442604866@linuxfoundation.org> (raw)
In-Reply-To: <20220127180258.362000607@linuxfoundation.org>
From: Paul E. McKenney <paulmck@kernel.org>
commit 614ddad17f22a22e035e2ea37a04815f50362017 upstream.
Currently, rcu_advance_cbs_nowake() checks that a grace period is in
progress, however, that grace period could end just after the check.
This commit rechecks that a grace period is still in progress while
holding the rcu_node structure's lock. The grace period cannot end while
the current CPU's rcu_node structure's ->lock is held, thus avoiding
false positives from the WARN_ON_ONCE().
As Daniel Vacek noted, it is not necessary for the rcu_node structure
to have a CPU that has not yet passed through its quiescent state.
Tested-by: Guillaume Morin <guillaume@morinfr.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/rcu/tree.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1358,10 +1358,11 @@ static void __maybe_unused rcu_advance_c
struct rcu_data *rdp)
{
rcu_lockdep_assert_cblist_protected(rdp);
- if (!rcu_seq_state(rcu_seq_current(&rnp->gp_seq)) ||
- !raw_spin_trylock_rcu_node(rnp))
+ if (!rcu_seq_state(rcu_seq_current(&rnp->gp_seq)) || !raw_spin_trylock_rcu_node(rnp))
return;
- WARN_ON_ONCE(rcu_advance_cbs(rnp, rdp));
+ // The grace period cannot end while we hold the rcu_node lock.
+ if (rcu_seq_state(rcu_seq_current(&rnp->gp_seq)))
+ WARN_ON_ONCE(rcu_advance_cbs(rnp, rdp));
raw_spin_unlock_rcu_node(rnp);
}
next prev parent reply other threads:[~2022-01-27 18:10 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-27 18:09 [PATCH 5.4 00/11] 5.4.175-rc1 review Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 01/11] drm/i915: Flush TLBs before releasing backing store Greg Kroah-Hartman
2022-01-27 18:09 ` Greg Kroah-Hartman [this message]
2022-01-27 18:09 ` [PATCH 5.4 03/11] pinctrl: bcm2835: Drop unused define Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 04/11] pinctrl: bcm2835: Refactor platform data Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 05/11] pinctrl: bcm2835: Add support for all GPIOs on BCM2711 Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 06/11] pinctrl: bcm2835: Match BCM7211 compatible string Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 07/11] pinctrl: bcm2835: Add support for wake-up interrupts Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 08/11] pinctrl: bcm2835: Change init order for gpio hogs Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 09/11] ARM: dts: gpio-ranges property is now required Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 10/11] mmc: sdhci-esdhc-imx: disable CMDQ support Greg Kroah-Hartman
2022-01-27 18:09 ` [PATCH 5.4 11/11] select: Fix indefinitely sleeping task in poll_schedule_timeout() Greg Kroah-Hartman
2022-01-27 19:00 ` [PATCH 5.4 00/11] 5.4.175-rc1 review Florian Fainelli
2022-01-28 1:17 ` Shuah Khan
2022-01-28 11:38 ` Naresh Kamboju
2022-01-28 14:24 ` Sudip Mukherjee
2022-01-29 1:06 ` Guenter Roeck
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