diff options
Diffstat (limited to 'features/rt/u64_stats-Disable-preemption-on-32bit-UP-SMP-with-RT.patch')
| -rw-r--r-- | features/rt/u64_stats-Disable-preemption-on-32bit-UP-SMP-with-RT.patch | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/features/rt/u64_stats-Disable-preemption-on-32bit-UP-SMP-with-RT.patch b/features/rt/u64_stats-Disable-preemption-on-32bit-UP-SMP-with-RT.patch new file mode 100644 index 00000000..af52aa75 --- /dev/null +++ b/features/rt/u64_stats-Disable-preemption-on-32bit-UP-SMP-with-RT.patch @@ -0,0 +1,151 @@ +From f134d18cc24a5f4bbd6fa3b658749d22a00136c6 Mon Sep 17 00:00:00 2001 +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Mon, 17 Aug 2020 12:28:10 +0200 +Subject: [PATCH 088/191] u64_stats: Disable preemption on 32bit-UP/SMP with RT + during updates + +On RT the seqcount_t is required even on UP because the softirq can be +preempted. The IRQ handler is threaded so it is also preemptible. + +Disable preemption on 32bit-RT during value updates. There is no need to +disable interrupts on RT because the handler is run threaded. Therefore +disabling preemption is enough to guarantee that the update is not +interruped. + +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + include/linux/u64_stats_sync.h | 42 ++++++++++++++++++++++------------ + 1 file changed, 28 insertions(+), 14 deletions(-) + +diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h +index e81856c0ba13..66eb968a09d4 100644 +--- a/include/linux/u64_stats_sync.h ++++ b/include/linux/u64_stats_sync.h +@@ -66,7 +66,7 @@ + #include <linux/seqlock.h> + + struct u64_stats_sync { +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG==32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) + seqcount_t seq; + #endif + }; +@@ -115,7 +115,7 @@ static inline void u64_stats_inc(u64_stats_t *p) + } + #endif + +-#if BITS_PER_LONG == 32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) + #define u64_stats_init(syncp) seqcount_init(&(syncp)->seq) + #else + static inline void u64_stats_init(struct u64_stats_sync *syncp) +@@ -125,15 +125,19 @@ static inline void u64_stats_init(struct u64_stats_sync *syncp) + + static inline void u64_stats_update_begin(struct u64_stats_sync *syncp) + { +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) ++ if (IS_ENABLED(CONFIG_PREEMPT_RT)) ++ preempt_disable(); + write_seqcount_begin(&syncp->seq); + #endif + } + + static inline void u64_stats_update_end(struct u64_stats_sync *syncp) + { +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) + write_seqcount_end(&syncp->seq); ++ if (IS_ENABLED(CONFIG_PREEMPT_RT)) ++ preempt_enable(); + #endif + } + +@@ -142,8 +146,11 @@ u64_stats_update_begin_irqsave(struct u64_stats_sync *syncp) + { + unsigned long flags = 0; + +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) +- local_irq_save(flags); ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) ++ if (IS_ENABLED(CONFIG_PREEMPT_RT)) ++ preempt_disable(); ++ else ++ local_irq_save(flags); + write_seqcount_begin(&syncp->seq); + #endif + return flags; +@@ -153,15 +160,18 @@ static inline void + u64_stats_update_end_irqrestore(struct u64_stats_sync *syncp, + unsigned long flags) + { +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) + write_seqcount_end(&syncp->seq); +- local_irq_restore(flags); ++ if (IS_ENABLED(CONFIG_PREEMPT_RT)) ++ preempt_enable(); ++ else ++ local_irq_restore(flags); + #endif + } + + static inline unsigned int __u64_stats_fetch_begin(const struct u64_stats_sync *syncp) + { +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) + return read_seqcount_begin(&syncp->seq); + #else + return 0; +@@ -170,7 +180,7 @@ static inline unsigned int __u64_stats_fetch_begin(const struct u64_stats_sync * + + static inline unsigned int u64_stats_fetch_begin(const struct u64_stats_sync *syncp) + { +-#if BITS_PER_LONG==32 && !defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (!defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_RT)) + preempt_disable(); + #endif + return __u64_stats_fetch_begin(syncp); +@@ -179,7 +189,7 @@ static inline unsigned int u64_stats_fetch_begin(const struct u64_stats_sync *sy + static inline bool __u64_stats_fetch_retry(const struct u64_stats_sync *syncp, + unsigned int start) + { +-#if BITS_PER_LONG==32 && defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)) + return read_seqcount_retry(&syncp->seq, start); + #else + return false; +@@ -189,7 +199,7 @@ static inline bool __u64_stats_fetch_retry(const struct u64_stats_sync *syncp, + static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp, + unsigned int start) + { +-#if BITS_PER_LONG==32 && !defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && (!defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_RT)) + preempt_enable(); + #endif + return __u64_stats_fetch_retry(syncp, start); +@@ -203,7 +213,9 @@ static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp, + */ + static inline unsigned int u64_stats_fetch_begin_irq(const struct u64_stats_sync *syncp) + { +-#if BITS_PER_LONG==32 && !defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && defined(CONFIG_PREEMPT_RT) ++ preempt_disable(); ++#elif BITS_PER_LONG == 32 && !defined(CONFIG_SMP) + local_irq_disable(); + #endif + return __u64_stats_fetch_begin(syncp); +@@ -212,7 +224,9 @@ static inline unsigned int u64_stats_fetch_begin_irq(const struct u64_stats_sync + static inline bool u64_stats_fetch_retry_irq(const struct u64_stats_sync *syncp, + unsigned int start) + { +-#if BITS_PER_LONG==32 && !defined(CONFIG_SMP) ++#if BITS_PER_LONG == 32 && defined(CONFIG_PREEMPT_RT) ++ preempt_enable(); ++#elif BITS_PER_LONG == 32 && !defined(CONFIG_SMP) + local_irq_enable(); + #endif + return __u64_stats_fetch_retry(syncp, start); +-- +2.19.1 + |