Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.4 26/37] u64_stats,lockdep: Fix u64_stats_init() vs lockdep | Date | Tue, 16 Mar 2021 20:57:51 -0400 |
| |
From: Peter Zijlstra <peterz@infradead.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@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> --- 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
| |