From d5b0e0677bfd5efd17c5bbb00156931f0d41cb85 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 8 Mar 2021 09:38:12 +0100 Subject: u64_stats,lockdep: Fix u64_stats_init() vs lockdep 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 Debugged-by: "Ahmed S. Darwish" Signed-off-by: Peter Zijlstra (Intel) Tested-by: "Erhard F." Link: https://lkml.kernel.org/r/YEXicy6+9MksdLZh@hirez.programming.kicks-ass.net --- include/linux/u64_stats_sync.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include') 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) { -- cgit v1.2.3 From 4817a52b306136c8b2b2271d8770401441e4cf79 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 9 Mar 2021 15:21:18 +0100 Subject: seqlock,lockdep: Fix seqcount_latch_init() seqcount_init() must be a macro in order to preserve the static variable that is used for the lockdep key. Don't then wrap it in an inline function, which destroys that. Luckily there aren't many users of this function, but fix it before it becomes a problem. Fixes: 80793c3471d9 ("seqlock: Introduce seqcount_latch_t") Reported-by: Eric Dumazet Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/YEeFEbNUVkZaXDp4@hirez.programming.kicks-ass.net --- include/linux/seqlock.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 2f7bb92b4c9e..f61e34fbaaea 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -664,10 +664,7 @@ typedef struct { * seqcount_latch_init() - runtime initializer for seqcount_latch_t * @s: Pointer to the seqcount_latch_t instance */ -static inline void seqcount_latch_init(seqcount_latch_t *s) -{ - seqcount_init(&s->seqcount); -} +#define seqcount_latch_init(s) seqcount_init(&(s)->seqcount) /** * raw_read_seqcount_latch() - pick even/odd latch data copy -- cgit v1.2.3