diff options
Diffstat (limited to 'debian/patches-rt/0031-timekeeping-Split-jiffies-seqlock.patch')
| -rw-r--r-- | debian/patches-rt/0031-timekeeping-Split-jiffies-seqlock.patch | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/debian/patches-rt/0031-timekeeping-Split-jiffies-seqlock.patch b/debian/patches-rt/0031-timekeeping-Split-jiffies-seqlock.patch new file mode 100644 index 000000000..0b4af0dee --- /dev/null +++ b/debian/patches-rt/0031-timekeeping-Split-jiffies-seqlock.patch @@ -0,0 +1,171 @@ +From 8af466b69f15bf4b922703f7b7d6bba72f2ae86c Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 14 Feb 2013 22:36:59 +0100 +Subject: [PATCH 031/347] timekeeping: Split jiffies seqlock +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +Replace jiffies_lock seqlock with a simple seqcounter and a rawlock so +it can be taken in atomic context on RT. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + kernel/time/jiffies.c | 7 ++++--- + kernel/time/tick-common.c | 10 ++++++---- + kernel/time/tick-sched.c | 19 ++++++++++++------- + kernel/time/timekeeping.c | 6 ++++-- + kernel/time/timekeeping.h | 3 ++- + 5 files changed, 28 insertions(+), 17 deletions(-) + +diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c +index 497719127bf9..62acb8914c9e 100644 +--- a/kernel/time/jiffies.c ++++ b/kernel/time/jiffies.c +@@ -74,7 +74,8 @@ static struct clocksource clocksource_jiffies = { + .max_cycles = 10, + }; + +-__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock); ++__cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock); ++__cacheline_aligned_in_smp seqcount_t jiffies_seq; + + #if (BITS_PER_LONG < 64) + u64 get_jiffies_64(void) +@@ -83,9 +84,9 @@ u64 get_jiffies_64(void) + u64 ret; + + do { +- seq = read_seqbegin(&jiffies_lock); ++ seq = read_seqcount_begin(&jiffies_seq); + ret = jiffies_64; +- } while (read_seqretry(&jiffies_lock, seq)); ++ } while (read_seqcount_retry(&jiffies_seq, seq)); + return ret; + } + EXPORT_SYMBOL(get_jiffies_64); +diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c +index 0a3cc37e4b83..7bd136b646d4 100644 +--- a/kernel/time/tick-common.c ++++ b/kernel/time/tick-common.c +@@ -80,13 +80,15 @@ int tick_is_oneshot_available(void) + static void tick_periodic(int cpu) + { + if (tick_do_timer_cpu == cpu) { +- write_seqlock(&jiffies_lock); ++ raw_spin_lock(&jiffies_lock); ++ write_seqcount_begin(&jiffies_seq); + + /* Keep track of the next tick event */ + tick_next_period = ktime_add(tick_next_period, tick_period); + + do_timer(1); +- write_sequnlock(&jiffies_lock); ++ write_seqcount_end(&jiffies_seq); ++ raw_spin_unlock(&jiffies_lock); + update_wall_time(); + } + +@@ -158,9 +160,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast) + ktime_t next; + + do { +- seq = read_seqbegin(&jiffies_lock); ++ seq = read_seqcount_begin(&jiffies_seq); + next = tick_next_period; +- } while (read_seqretry(&jiffies_lock, seq)); ++ } while (read_seqcount_retry(&jiffies_seq, seq)); + + clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); + +diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c +index 48403fb653c2..e774a49176cc 100644 +--- a/kernel/time/tick-sched.c ++++ b/kernel/time/tick-sched.c +@@ -68,7 +68,8 @@ static void tick_do_update_jiffies64(ktime_t now) + return; + + /* Reevaluate with jiffies_lock held */ +- write_seqlock(&jiffies_lock); ++ raw_spin_lock(&jiffies_lock); ++ write_seqcount_begin(&jiffies_seq); + + delta = ktime_sub(now, last_jiffies_update); + if (delta >= tick_period) { +@@ -94,10 +95,12 @@ static void tick_do_update_jiffies64(ktime_t now) + /* Keep the tick_next_period variable up to date */ + tick_next_period = ktime_add(last_jiffies_update, tick_period); + } else { +- write_sequnlock(&jiffies_lock); ++ write_seqcount_end(&jiffies_seq); ++ raw_spin_unlock(&jiffies_lock); + return; + } +- write_sequnlock(&jiffies_lock); ++ write_seqcount_end(&jiffies_seq); ++ raw_spin_unlock(&jiffies_lock); + update_wall_time(); + } + +@@ -108,12 +111,14 @@ static ktime_t tick_init_jiffy_update(void) + { + ktime_t period; + +- write_seqlock(&jiffies_lock); ++ raw_spin_lock(&jiffies_lock); ++ write_seqcount_begin(&jiffies_seq); + /* Did we start the jiffies update yet ? */ + if (last_jiffies_update == 0) + last_jiffies_update = tick_next_period; + period = last_jiffies_update; +- write_sequnlock(&jiffies_lock); ++ write_seqcount_end(&jiffies_seq); ++ raw_spin_unlock(&jiffies_lock); + return period; + } + +@@ -656,10 +661,10 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu) + + /* Read jiffies and the time when jiffies were updated last */ + do { +- seq = read_seqbegin(&jiffies_lock); ++ seq = read_seqcount_begin(&jiffies_seq); + basemono = last_jiffies_update; + basejiff = jiffies; +- } while (read_seqretry(&jiffies_lock, seq)); ++ } while (read_seqcount_retry(&jiffies_seq, seq)); + ts->last_jiffies = basejiff; + ts->timer_expires_base = basemono; + +diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c +index f246818e35db..2cc8a1e8e94f 100644 +--- a/kernel/time/timekeeping.c ++++ b/kernel/time/timekeeping.c +@@ -2392,8 +2392,10 @@ EXPORT_SYMBOL(hardpps); + */ + void xtime_update(unsigned long ticks) + { +- write_seqlock(&jiffies_lock); ++ raw_spin_lock(&jiffies_lock); ++ write_seqcount_begin(&jiffies_seq); + do_timer(ticks); +- write_sequnlock(&jiffies_lock); ++ write_seqcount_end(&jiffies_seq); ++ raw_spin_unlock(&jiffies_lock); + update_wall_time(); + } +diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h +index 141ab3ab0354..099737f6f10c 100644 +--- a/kernel/time/timekeeping.h ++++ b/kernel/time/timekeeping.h +@@ -25,7 +25,8 @@ static inline void sched_clock_resume(void) { } + extern void do_timer(unsigned long ticks); + extern void update_wall_time(void); + +-extern seqlock_t jiffies_lock; ++extern raw_spinlock_t jiffies_lock; ++extern seqcount_t jiffies_seq; + + #define CS_NAME_LEN 32 + +-- +2.36.1 + |