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Message-Id: <20210329075610.877791027@linuxfoundation.org>
Date: Mon, 29 Mar 2021 09:57:54 +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, Jakub Kicinski <kuba@...nel.org>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
"Erhard F." <erhard_f@...lbox.org>,
Sasha Levin <sashal@...nel.org>,
"Ahmed S. Darwish" <a.darwish@...utronix.de>
Subject: [PATCH 4.19 18/72] u64_stats,lockdep: Fix u64_stats_init() vs lockdep
From: Peter Zijlstra <peterz@...radead.org>
[ Upstream commit d5b0e0677bfd5efd17c5bbb00156931f0d41cb85 ]
Jakub reported that:
static struct net_device *rtl8139_init_board(struct pci_dev *pdev)
{
...
u64_stats_init(&tp->rx_stats.syncp);
u64_stats_init(&tp->tx_stats.syncp);
...
}
results in lockdep getting confused between the RX and TX stats lock.
This is because u64_stats_init() is an inline calling seqcount_init(),
which is a macro using a static variable to generate a lockdep class.
By wrapping that in an inline, we negate the effect of the macro and
fold the static key variable, hence the confusion.
Fix by also making u64_stats_init() a macro for the case where it
matters, leaving the other case an inline for argument validation
etc.
Reported-by: Jakub Kicinski <kuba@...nel.org>
Debugged-by: "Ahmed S. Darwish" <a.darwish@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: "Erhard F." <erhard_f@...lbox.org>
Link: https://lkml.kernel.org/r/YEXicy6+9MksdLZh@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
include/linux/u64_stats_sync.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h
index a27604f99ed0..11096b561dab 100644
--- a/include/linux/u64_stats_sync.h
+++ b/include/linux/u64_stats_sync.h
@@ -69,12 +69,13 @@ struct u64_stats_sync {
};
+#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
+#define u64_stats_init(syncp) seqcount_init(&(syncp)->seq)
+#else
static inline void u64_stats_init(struct u64_stats_sync *syncp)
{
-#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
- seqcount_init(&syncp->seq);
-#endif
}
+#endif
static inline void u64_stats_update_begin(struct u64_stats_sync *syncp)
{
--
2.30.1
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