diff options
| -rw-r--r-- | include/linux/rcupdate.h | 5 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 18 | ||||
| -rw-r--r-- | kernel/trace/trace_stack.c | 8 |
3 files changed, 29 insertions, 2 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index de88b33c0974..dea8f17b2fe3 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -97,6 +97,7 @@ void do_trace_rcu_torture_read(const char *rcutorturename, unsigned long secs, unsigned long c_old, unsigned long c); +bool rcu_irq_enter_disabled(void); #else static inline void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, @@ -113,6 +114,10 @@ static inline void rcutorture_record_test_transition(void) static inline void rcutorture_record_progress(unsigned long vernum) { } +static inline bool rcu_irq_enter_disabled(void) +{ + return false; +} #ifdef CONFIG_RCU_TRACE void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8b4d273331e4..a6dcf3bd244f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -285,6 +285,20 @@ static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { }; /* + * There's a few places, currently just in the tracing infrastructure, + * that uses rcu_irq_enter() to make sure RCU is watching. But there's + * a small location where that will not even work. In those cases + * rcu_irq_enter_disabled() needs to be checked to make sure rcu_irq_enter() + * can be called. + */ +static DEFINE_PER_CPU(bool, disable_rcu_irq_enter); + +bool rcu_irq_enter_disabled(void) +{ + return this_cpu_read(disable_rcu_irq_enter); +} + +/* * Record entry into an extended quiescent state. This is only to be * called when not already in an extended quiescent state. */ @@ -800,10 +814,10 @@ static void rcu_eqs_enter_common(bool user) do_nocb_deferred_wakeup(rdp); } rcu_prepare_for_idle(); - stack_tracer_disable(); + __this_cpu_inc(disable_rcu_irq_enter); rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */ rcu_dynticks_eqs_enter(); /* After this, tracing works again. */ - stack_tracer_enable(); + __this_cpu_dec(disable_rcu_irq_enter); rcu_dynticks_task_enter(); /* diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index f2f02ff350d4..76aa04d4c925 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -96,6 +96,14 @@ check_stack(unsigned long ip, unsigned long *stack) if (in_nmi()) return; + /* + * There's a slight chance that we are tracing inside the + * RCU infrastructure, and rcu_irq_enter() will not work + * as expected. + */ + if (unlikely(rcu_irq_enter_disabled())) + return; + local_irq_save(flags); arch_spin_lock(&stack_trace_max_lock); |