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Message-Id: <20200623195411.952647146@linuxfoundation.org>
Date: Tue, 23 Jun 2020 21:51:29 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
"Ahmed S. Darwish" <a.darwish@...utronix.de>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
"David S. Miller" <davem@...emloft.net>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 092/477] net: mdiobus: Disable preemption upon u64_stats update
From: Ahmed S. Darwish <a.darwish@...utronix.de>
[ Upstream commit c7e261d81783387a0502878cd229327e7c54322e ]
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@...el.com>
Signed-off-by: Ahmed S. Darwish <a.darwish@...utronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
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 7a4eb3f2cb743..a1a4dee2a033a 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();
}
/**
--
2.25.1
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