| Message ID | 1346352988-32444-2-git-send-email-paulmck@linux.vnet.ibm.com |
|---|---|
| State | Accepted |
| Commit | 818615c4cde2a71a5857007b134cce89d506cc3f |
| Headers | show |
On Thu, Aug 30, 2012 at 11:56:15AM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" <paul.mckenney@linaro.org> > > Because TINY_RCU's idle detection keys directly off of the nesting > level, rather than from a separate variable as in TREE_RCU, the > TINY_RCU dyntick-idle tracing on transition to idle must happen > before the change to the nesting level. This commit therefore makes > this change by passing the desired new value (rather than the old value) > of the nesting level in to rcu_idle_enter_common(). > > [ paulmck: Add fix for wrong-variable bug spotted by > Michael Wang <wangyun@linux.vnet.ibm.com>. ] > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> > --- > kernel/rcutiny.c | 31 ++++++++++++++++--------------- > 1 files changed, 16 insertions(+), 15 deletions(-) > > diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c > index 547b1fe..e4163c5 100644 > --- a/kernel/rcutiny.c > +++ b/kernel/rcutiny.c > @@ -56,24 +56,27 @@ static void __call_rcu(struct rcu_head *head, > static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; > > /* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ > -static void rcu_idle_enter_common(long long oldval) > +static void rcu_idle_enter_common(long long newval) > { > - if (rcu_dynticks_nesting) { > + if (newval) { > RCU_TRACE(trace_rcu_dyntick("--=", > - oldval, rcu_dynticks_nesting)); > + rcu_dynticks_nesting, newval)); > + rcu_dynticks_nesting = newval; > return; > } > - RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting)); > + RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting, newval)); > if (!is_idle_task(current)) { > struct task_struct *idle = idle_task(smp_processor_id()); > > RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", > - oldval, rcu_dynticks_nesting)); > + rcu_dynticks_nesting, newval)); > ftrace_dump(DUMP_ALL); > WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", > current->pid, current->comm, > idle->pid, idle->comm); /* must be idle task! */ > } > + barrier(); > + rcu_dynticks_nesting = newval; > rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ > } > > @@ -84,17 +87,16 @@ static void rcu_idle_enter_common(long long oldval) > void rcu_idle_enter(void) > { > unsigned long flags; > - long long oldval; > + long long newval; > > local_irq_save(flags); > - oldval = rcu_dynticks_nesting; > WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0); > if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == > DYNTICK_TASK_NEST_VALUE) > - rcu_dynticks_nesting = 0; > + newval = 0; > else > - rcu_dynticks_nesting -= DYNTICK_TASK_NEST_VALUE; > - rcu_idle_enter_common(oldval); > + newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE; > + rcu_idle_enter_common(newval); > local_irq_restore(flags); > } > EXPORT_SYMBOL_GPL(rcu_idle_enter); > @@ -105,13 +107,12 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter); > void rcu_irq_exit(void) > { > unsigned long flags; > - long long oldval; > + long long newval; > > local_irq_save(flags); > - oldval = rcu_dynticks_nesting; > - rcu_dynticks_nesting--; > - WARN_ON_ONCE(rcu_dynticks_nesting < 0); > - rcu_idle_enter_common(oldval); > + newval = rcu_dynticks_nesting - 1; > + WARN_ON_ONCE(newval < 0); > + rcu_idle_enter_common(newval); > local_irq_restore(flags); > } > > -- > 1.7.8 >
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 547b1fe..e4163c5 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -56,24 +56,27 @@ static void __call_rcu(struct rcu_head *head, static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; /* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ -static void rcu_idle_enter_common(long long oldval) +static void rcu_idle_enter_common(long long newval) { - if (rcu_dynticks_nesting) { + if (newval) { RCU_TRACE(trace_rcu_dyntick("--=", - oldval, rcu_dynticks_nesting)); + rcu_dynticks_nesting, newval)); + rcu_dynticks_nesting = newval; return; } - RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting)); + RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting, newval)); if (!is_idle_task(current)) { struct task_struct *idle = idle_task(smp_processor_id()); RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", - oldval, rcu_dynticks_nesting)); + rcu_dynticks_nesting, newval)); ftrace_dump(DUMP_ALL); WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", current->pid, current->comm, idle->pid, idle->comm); /* must be idle task! */ } + barrier(); + rcu_dynticks_nesting = newval; rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ } @@ -84,17 +87,16 @@ static void rcu_idle_enter_common(long long oldval) void rcu_idle_enter(void) { unsigned long flags; - long long oldval; + long long newval; local_irq_save(flags); - oldval = rcu_dynticks_nesting; WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0); if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) - rcu_dynticks_nesting = 0; + newval = 0; else - rcu_dynticks_nesting -= DYNTICK_TASK_NEST_VALUE; - rcu_idle_enter_common(oldval); + newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE; + rcu_idle_enter_common(newval); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(rcu_idle_enter); @@ -105,13 +107,12 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter); void rcu_irq_exit(void) { unsigned long flags; - long long oldval; + long long newval; local_irq_save(flags); - oldval = rcu_dynticks_nesting; - rcu_dynticks_nesting--; - WARN_ON_ONCE(rcu_dynticks_nesting < 0); - rcu_idle_enter_common(oldval); + newval = rcu_dynticks_nesting - 1; + WARN_ON_ONCE(newval < 0); + rcu_idle_enter_common(newval); local_irq_restore(flags); }