diff options
| -rw-r--r-- | include/linux/u64_stats_sync.h | 59 |
1 files changed, 44 insertions, 15 deletions
diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h index b38e3a5..fa261a0 100644 --- a/include/linux/u64_stats_sync.h +++ b/include/linux/u64_stats_sync.h @@ -27,6 +27,9 @@ * (On UP, there is no seqcount_t protection, a reader allowing interrupts could * read partial values) * + * 7) For softirq uses, readers can use u64_stats_fetch_begin_bh() and + * u64_stats_fetch_retry_bh() helpers + * * Usage : * * Stats producer (writer) should use following template granted it already got @@ -58,54 +61,80 @@ */ #include <linux/seqlock.h> -#if BITS_PER_LONG==32 && defined(CONFIG_SMP) struct u64_stats_sync { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) seqcount_t seq; +#endif }; static void inline u64_stats_update_begin(struct u64_stats_sync *syncp) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) write_seqcount_begin(&syncp->seq); +#endif } static void inline u64_stats_update_end(struct u64_stats_sync *syncp) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) write_seqcount_end(&syncp->seq); +#endif } static unsigned int inline u64_stats_fetch_begin(const struct u64_stats_sync *syncp) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) return read_seqcount_begin(&syncp->seq); +#else +#if BITS_PER_LONG==32 + preempt_disable(); +#endif + return 0; +#endif } static bool inline u64_stats_fetch_retry(const struct u64_stats_sync *syncp, unsigned int start) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) return read_seqcount_retry(&syncp->seq, start); -} - #else -struct u64_stats_sync { -}; - -static void inline u64_stats_update_begin(struct u64_stats_sync *syncp) -{ -} - -static void inline u64_stats_update_end(struct u64_stats_sync *syncp) -{ +#if BITS_PER_LONG==32 + preempt_enable(); +#endif + return false; +#endif } -static unsigned int inline u64_stats_fetch_begin(const struct u64_stats_sync *syncp) +/* + * In case softirq handlers can update u64 counters, readers can use following helpers + * - SMP 32bit arches use seqcount protection, irq safe. + * - UP 32bit must disable BH. + * - 64bit have no problem atomically reading u64 values, irq safe. + */ +static unsigned int inline u64_stats_fetch_begin_bh(const struct u64_stats_sync *syncp) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + return read_seqcount_begin(&syncp->seq); +#else +#if BITS_PER_LONG==32 + local_bh_disable(); +#endif return 0; +#endif } -static bool inline u64_stats_fetch_retry(const struct u64_stats_sync *syncp, +static bool inline u64_stats_fetch_retry_bh(const struct u64_stats_sync *syncp, unsigned int start) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + return read_seqcount_retry(&syncp->seq, start); +#else +#if BITS_PER_LONG==32 + local_bh_enable(); +#endif return false; -} #endif +} #endif /* _LINUX_U64_STATS_SYNC_H */ |