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 c6abb79501b3..e81856c0ba13 100644 --- a/include/linux/u64_stats_sync.h +++ b/include/linux/u64_stats_sync.h @@ -115,12 +115,13 @@ static inline void u64_stats_inc(u64_stats_t *p) } #endif
+#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) {