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 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 index 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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