From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Sebastian A. Siewior" <bigeasy@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
"Ahmed S. Darwish" <a.darwish@linutronix.de>,
Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
Heiner Kallweit <hkallweit1@gmail.com>,
Russell King <linux@armlinux.org.uk>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
netdev@vger.kernel.org
Subject: [PATCH v2 4/6] net: mdiobus: Disable preemption upon u64_stats update
Date: Wed, 3 Jun 2020 16:49:47 +0200 [thread overview]
Message-ID: <20200603144949.1122421-5-a.darwish@linutronix.de> (raw)
In-Reply-To: <20200603144949.1122421-1-a.darwish@linutronix.de>
The u64_stats mechanism uses sequence counters to protect against 64-bit
values tearing on 32-bit architectures. Updating u64_stats is thus a
sequence counter write side critical section where preemption must be
disabled.
For mdiobus_stats_acct(), disable preemption upon the u64_stats update.
It is called from process context through mdiobus_read() and
mdiobus_write().
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/net/phy/mdio_bus.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 7a4eb3f2cb74..a1a4dee2a033 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -757,6 +757,7 @@ EXPORT_SYMBOL(mdiobus_scan);
static void mdiobus_stats_acct(struct mdio_bus_stats *stats, bool op, int ret)
{
+ preempt_disable();
u64_stats_update_begin(&stats->syncp);
u64_stats_inc(&stats->transfers);
@@ -771,6 +772,7 @@ static void mdiobus_stats_acct(struct mdio_bus_stats *stats, bool op, int ret)
u64_stats_inc(&stats->writes);
out:
u64_stats_update_end(&stats->syncp);
+ preempt_enable();
}
/**
--
2.20.1
next prev parent reply other threads:[~2020-06-03 14:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-03 14:49 [PATCH v2 0/6] seqlock: seqcount_t call sites bugfixes Ahmed S. Darwish
2020-06-03 14:49 ` [PATCH v2 1/6] net: core: device_rename: Use rwsem instead of a seqcount Ahmed S. Darwish
2020-06-03 14:49 ` [PATCH v2 2/6] net: phy: fixed_phy: Remove unused seqcount Ahmed S. Darwish
2020-06-03 16:19 ` Andrew Lunn
2020-06-03 14:49 ` [PATCH v2 3/6] u64_stats: Document writer non-preemptibility requirement Ahmed S. Darwish
2020-06-03 14:49 ` Ahmed S. Darwish [this message]
2020-06-03 14:49 ` [PATCH v2 5/6] block: nr_sects_write(): Disable preemption on seqcount write Ahmed S. Darwish
2020-06-05 3:22 ` Jens Axboe
2020-06-03 14:49 ` [PATCH v2 6/6] dma-buf: Remove custom seqcount lockdep class key Ahmed S. Darwish
2020-06-04 8:49 ` Daniel Vetter
2020-06-04 7:28 ` [PATCH v2 0/6] seqlock: seqcount_t call sites bugfixes Daniel Vetter
2020-06-04 8:41 ` Ahmed S. Darwish
2020-06-04 22:50 ` David Miller
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