diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcu.h | 7 | ||||
| -rw-r--r-- | kernel/rcutiny.c | 28 | ||||
| -rw-r--r-- | kernel/rcutree.c | 35 |
3 files changed, 44 insertions, 26 deletions
diff --git a/kernel/rcu.h b/kernel/rcu.h index f600868d550..aa88baab5f7 100644 --- a/kernel/rcu.h +++ b/kernel/rcu.h @@ -30,6 +30,13 @@ #endif /* #else #ifdef CONFIG_RCU_TRACE */ /* + * Process-level increment to ->dynticks_nesting field. This allows for + * architectures that use half-interrupts and half-exceptions from + * process context. + */ +#define DYNTICK_TASK_NESTING (LLONG_MAX / 2 - 1) + +/* * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally * by call_rcu() and rcu callback execution, and are therefore not part of the * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors. diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index b4e0b498176..9b9bdf666fb 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -53,20 +53,21 @@ static void __call_rcu(struct rcu_head *head, #include "rcutiny_plugin.h" -static long long rcu_dynticks_nesting = LLONG_MAX / 2; +static long long rcu_dynticks_nesting = DYNTICK_TASK_NESTING; /* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ -static void rcu_idle_enter_common(void) +static void rcu_idle_enter_common(long long oldval) { if (rcu_dynticks_nesting) { - RCU_TRACE(trace_rcu_dyntick("--=", rcu_dynticks_nesting)); + RCU_TRACE(trace_rcu_dyntick("--=", + oldval, rcu_dynticks_nesting)); return; } - RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting)); + RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting)); if (!idle_cpu(smp_processor_id())) { WARN_ON_ONCE(1); /* must be idle task! */ RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", - rcu_dynticks_nesting)); + oldval, rcu_dynticks_nesting)); ftrace_dump(DUMP_ALL); } rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ @@ -79,10 +80,12 @@ static void rcu_idle_enter_common(void) void rcu_idle_enter(void) { unsigned long flags; + long long oldval; local_irq_save(flags); + oldval = rcu_dynticks_nesting; rcu_dynticks_nesting = 0; - rcu_idle_enter_common(); + rcu_idle_enter_common(oldval); local_irq_restore(flags); } @@ -92,11 +95,13 @@ void rcu_idle_enter(void) void rcu_irq_exit(void) { unsigned long flags; + long long oldval; local_irq_save(flags); + oldval = rcu_dynticks_nesting; rcu_dynticks_nesting--; WARN_ON_ONCE(rcu_dynticks_nesting < 0); - rcu_idle_enter_common(); + rcu_idle_enter_common(oldval); local_irq_restore(flags); } @@ -104,14 +109,15 @@ void rcu_irq_exit(void) static void rcu_idle_exit_common(long long oldval) { if (oldval) { - RCU_TRACE(trace_rcu_dyntick("++=", rcu_dynticks_nesting)); + RCU_TRACE(trace_rcu_dyntick("++=", + oldval, rcu_dynticks_nesting)); return; } - RCU_TRACE(trace_rcu_dyntick("End", oldval)); + RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting)); if (!idle_cpu(smp_processor_id())) { WARN_ON_ONCE(1); /* must be idle task! */ RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task", - oldval)); + oldval, rcu_dynticks_nesting)); ftrace_dump(DUMP_ALL); } } @@ -127,7 +133,7 @@ void rcu_idle_exit(void) local_irq_save(flags); oldval = rcu_dynticks_nesting; WARN_ON_ONCE(oldval != 0); - rcu_dynticks_nesting = LLONG_MAX / 2; + rcu_dynticks_nesting = DYNTICK_TASK_NESTING; rcu_idle_exit_common(oldval); local_irq_restore(flags); } diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 489b62a67d3..06e40dd53b2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -196,7 +196,7 @@ void rcu_note_context_switch(int cpu) EXPORT_SYMBOL_GPL(rcu_note_context_switch); DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { - .dynticks_nesting = LLONG_MAX / 2, + .dynticks_nesting = DYNTICK_TASK_NESTING, .dynticks = ATOMIC_INIT(1), }; @@ -348,17 +348,17 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) * we really have entered idle, and must do the appropriate accounting. * The caller must have disabled interrupts. */ -static void rcu_idle_enter_common(struct rcu_dynticks *rdtp) +static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) { if (rdtp->dynticks_nesting) { - trace_rcu_dyntick("--=", rdtp->dynticks_nesting); + trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); return; } - trace_rcu_dyntick("Start", rdtp->dynticks_nesting); + trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting); if (!idle_cpu(smp_processor_id())) { WARN_ON_ONCE(1); /* must be idle task! */ trace_rcu_dyntick("Error on entry: not idle task", - rdtp->dynticks_nesting); + oldval, rdtp->dynticks_nesting); ftrace_dump(DUMP_ALL); } /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ @@ -383,12 +383,14 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp) void rcu_idle_enter(void) { unsigned long flags; + long long oldval; struct rcu_dynticks *rdtp; local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); + oldval = rdtp->dynticks_nesting; rdtp->dynticks_nesting = 0; - rcu_idle_enter_common(rdtp); + rcu_idle_enter_common(rdtp, oldval); local_irq_restore(flags); } @@ -411,13 +413,15 @@ void rcu_idle_enter(void) void rcu_irq_exit(void) { unsigned long flags; + long long oldval; struct rcu_dynticks *rdtp; local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); + oldval = rdtp->dynticks_nesting; rdtp->dynticks_nesting--; WARN_ON_ONCE(rdtp->dynticks_nesting < 0); - rcu_idle_enter_common(rdtp); + rcu_idle_enter_common(rdtp, oldval); local_irq_restore(flags); } @@ -431,7 +435,7 @@ void rcu_irq_exit(void) static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) { if (oldval) { - trace_rcu_dyntick("++=", rdtp->dynticks_nesting); + trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); return; } smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ @@ -439,10 +443,11 @@ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ smp_mb__after_atomic_inc(); /* See above. */ WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); - trace_rcu_dyntick("End", oldval); + trace_rcu_dyntick("End", oldval, rdtp->dynticks_nesting); if (!idle_cpu(smp_processor_id())) { WARN_ON_ONCE(1); /* must be idle task! */ - trace_rcu_dyntick("Error on exit: not idle task", oldval); + trace_rcu_dyntick("Error on exit: not idle task", + oldval, rdtp->dynticks_nesting); ftrace_dump(DUMP_ALL); } } @@ -453,8 +458,8 @@ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) * Exit idle mode, in other words, -enter- the mode in which RCU * read-side critical sections can occur. * - * We crowbar the ->dynticks_nesting field to LLONG_MAX/2 to allow for - * the possibility of usermode upcalls messing up our count + * We crowbar the ->dynticks_nesting field to DYNTICK_TASK_NESTING to + * allow for the possibility of usermode upcalls messing up our count * of interrupt nesting level during the busy period that is just * now starting. */ @@ -468,7 +473,7 @@ void rcu_idle_exit(void) rdtp = &__get_cpu_var(rcu_dynticks); oldval = rdtp->dynticks_nesting; WARN_ON_ONCE(oldval != 0); - rdtp->dynticks_nesting = LLONG_MAX / 2; + rdtp->dynticks_nesting = DYNTICK_TASK_NESTING; rcu_idle_exit_common(rdtp, oldval); local_irq_restore(flags); } @@ -2012,7 +2017,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) rdp->nxttail[i] = &rdp->nxtlist; rdp->qlen = 0; rdp->dynticks = &per_cpu(rcu_dynticks, cpu); - WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != LLONG_MAX / 2); + WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_NESTING); WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); rdp->cpu = cpu; rdp->rsp = rsp; @@ -2040,7 +2045,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) rdp->qlen_last_fqs_check = 0; rdp->n_force_qs_snap = rsp->n_force_qs; rdp->blimit = blimit; - WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != LLONG_MAX / 2); + WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_NESTING); WARN_ON_ONCE((atomic_read(&rdp->dynticks->dynticks) & 0x1) != 1); raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |