HACK: ARM: disable sleeping while atomic warning in do_signal
[linux-2.6.git] / kernel / rcutiny.c
index 636af6d..37a5444 100644 (file)
@@ -53,31 +53,147 @@ static void __call_rcu(struct rcu_head *head,
 
 #include "rcutiny_plugin.h"
 
-#ifdef CONFIG_NO_HZ
+static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
 
-static long rcu_dynticks_nesting = 1;
+/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */
+static void rcu_idle_enter_common(long long oldval)
+{
+       if (rcu_dynticks_nesting) {
+               RCU_TRACE(trace_rcu_dyntick("--=",
+                                           oldval, rcu_dynticks_nesting));
+               return;
+       }
+       RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
+       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));
+               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! */
+       }
+       rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
+}
 
 /*
- * Enter dynticks-idle mode, which is an extended quiescent state
- * if we have fully entered that mode (i.e., if the new value of
- * dynticks_nesting is zero).
+ * Enter idle, which is an extended quiescent state if we have fully
+ * entered that mode (i.e., if the new value of dynticks_nesting is zero).
  */
-void rcu_enter_nohz(void)
+void rcu_idle_enter(void)
 {
-       if (--rcu_dynticks_nesting == 0)
-               rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
+       unsigned long flags;
+       long long oldval;
+
+       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;
+       else
+               rcu_dynticks_nesting  -= DYNTICK_TASK_NEST_VALUE;
+       rcu_idle_enter_common(oldval);
+       local_irq_restore(flags);
 }
+EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
 /*
- * Exit dynticks-idle mode, so that we are no longer in an extended
- * quiescent state.
+ * Exit an interrupt handler towards idle.
  */
-void rcu_exit_nohz(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(oldval);
+       local_irq_restore(flags);
+}
+
+/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */
+static void rcu_idle_exit_common(long long oldval)
 {
+       if (oldval) {
+               RCU_TRACE(trace_rcu_dyntick("++=",
+                                           oldval, rcu_dynticks_nesting));
+               return;
+       }
+       RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting));
+       if (!is_idle_task(current)) {
+               struct task_struct *idle = idle_task(smp_processor_id());
+
+               RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task",
+                         oldval, rcu_dynticks_nesting));
+               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! */
+       }
+}
+
+/*
+ * Exit idle, so that we are no longer in an extended quiescent state.
+ */
+void rcu_idle_exit(void)
+{
+       unsigned long flags;
+       long long oldval;
+
+       local_irq_save(flags);
+       oldval = rcu_dynticks_nesting;
+       WARN_ON_ONCE(rcu_dynticks_nesting < 0);
+       if (rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK)
+               rcu_dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
+       else
+               rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
+       rcu_idle_exit_common(oldval);
+       local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(rcu_idle_exit);
+
+/*
+ * Enter an interrupt handler, moving away from idle.
+ */
+void rcu_irq_enter(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_exit_common(oldval);
+       local_irq_restore(flags);
+}
+
+#ifdef CONFIG_PROVE_RCU
+
+/*
+ * Test whether RCU thinks that the current CPU is idle.
+ */
+int rcu_is_cpu_idle(void)
+{
+       return !rcu_dynticks_nesting;
 }
+EXPORT_SYMBOL(rcu_is_cpu_idle);
+
+#endif /* #ifdef CONFIG_PROVE_RCU */
 
-#endif /* #ifdef CONFIG_NO_HZ */
+/*
+ * Test whether the current CPU was interrupted from idle.  Nested
+ * interrupts don't count, we must be running at the first interrupt
+ * level.
+ */
+int rcu_is_cpu_rrupt_from_idle(void)
+{
+       return rcu_dynticks_nesting <= 0;
+}
 
 /*
  * Helper function for rcu_sched_qs() and rcu_bh_qs().
@@ -126,14 +242,13 @@ void rcu_bh_qs(int cpu)
 
 /*
  * Check to see if the scheduling-clock interrupt came from an extended
- * quiescent state, and, if so, tell RCU about it.
+ * quiescent state, and, if so, tell RCU about it.  This function must
+ * be called from hardirq context.  It is normally called from the
+ * scheduling-clock interrupt.
  */
 void rcu_check_callbacks(int cpu, int user)
 {
-       if (user ||
-           (idle_cpu(cpu) &&
-            !in_softirq() &&
-            hardirq_count() <= (1 << HARDIRQ_SHIFT)))
+       if (user || rcu_is_cpu_rrupt_from_idle())
                rcu_sched_qs(cpu);
        else if (!in_softirq())
                rcu_bh_qs(cpu);
@@ -153,14 +268,18 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
 
        /* If no RCU callbacks ready to invoke, just return. */
        if (&rcp->rcucblist == rcp->donetail) {
-               RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1));
-               RCU_TRACE(trace_rcu_batch_end(rcp->name, 0));
+               RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, 0, -1));
+               RCU_TRACE(trace_rcu_batch_end(rcp->name, 0,
+                                             ACCESS_ONCE(rcp->rcucblist),
+                                             need_resched(),
+                                             is_idle_task(current),
+                                             rcu_is_callbacks_kthread()));
                return;
        }
 
        /* Move the ready-to-invoke callbacks to a local list. */
        local_irq_save(flags);
-       RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1));
+       RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, rcp->qlen, -1));
        list = rcp->rcucblist;
        rcp->rcucblist = *rcp->donetail;
        *rcp->donetail = NULL;
@@ -183,7 +302,9 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
                RCU_TRACE(cb_count++);
        }
        RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count));
-       RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count));
+       RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count, 0, need_resched(),
+                                     is_idle_task(current),
+                                     rcu_is_callbacks_kthread()));
 }
 
 static void rcu_process_callbacks(struct softirq_action *unused)
@@ -208,6 +329,10 @@ static void rcu_process_callbacks(struct softirq_action *unused)
  */
 void synchronize_sched(void)
 {
+       rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
+                          !lock_is_held(&rcu_lock_map) &&
+                          !lock_is_held(&rcu_sched_lock_map),
+                          "Illegal synchronize_sched() in RCU read-side critical section");
        cond_resched();
 }
 EXPORT_SYMBOL_GPL(synchronize_sched);