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| author | Peter Zijlstra <peterz@infradead.org> | 2021-03-08 09:38:12 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-30 14:36:58 +0200 |
| commit | 3f405e14387a325e30d069bcd57e1184a0fd9aff (patch) | |
| tree | 7a85a4a3313424b42a64b32e0846f2b927de26a4 /include | |
| parent | d2003be29436a3d6197e1b673fce0c32413ce6d4 (diff) | |
| download | linux-3f405e14387a325e30d069bcd57e1184a0fd9aff.tar.gz linux-3f405e14387a325e30d069bcd57e1184a0fd9aff.tar.bz2 linux-3f405e14387a325e30d069bcd57e1184a0fd9aff.zip | |
u64_stats,lockdep: Fix u64_stats_init() vs lockdep
[ 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@kernel.org>
Debugged-by: "Ahmed S. Darwish" <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: "Erhard F." <erhard_f@mailbox.org>
Link: https://lkml.kernel.org/r/YEXicy6+9MksdLZh@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/u64_stats_sync.h | 7 |
1 files 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) { |