diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2021-03-08 09:38:12 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-03-10 09:51:45 +0100 |
| commit | d5b0e0677bfd5efd17c5bbb00156931f0d41cb85 (patch) | |
| tree | 5146fe6e9037f751b3629c32771d64c721f748c8 | |
| parent | 50bf8080a94d171e843fc013abec19d8ab9f50ae (diff) | |
| download | lwn-d5b0e0677bfd5efd17c5bbb00156931f0d41cb85.tar.gz lwn-d5b0e0677bfd5efd17c5bbb00156931f0d41cb85.zip | |
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 <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
| -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 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) { |