"Tree RCU": scalable classic RCU implementation

[safe/jmp/linux-2.6] / include / linux / hardirq.h

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 5912874..9b70b92 100644 (file)
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -1,9 +1,9 @@
 #ifndef LINUX_HARDIRQ_H
 #define LINUX_HARDIRQ_H
 
-#include <linux/config.h>
 #include <linux/preempt.h>
 #include <linux/smp_lock.h>
+#include <linux/lockdep.h>
 #include <asm/hardirq.h>
 #include <asm/system.h>
 
@@ -28,11 +28,16 @@
 
 #ifndef HARDIRQ_BITS
 #define HARDIRQ_BITS   12
+
+#ifndef MAX_HARDIRQS_PER_CPU
+#define MAX_HARDIRQS_PER_CPU NR_IRQS
+#endif
+
 /*
  * The hardirq mask has to be large enough to have space for potentially
  * all IRQ sources in the system nesting on a single CPU.
  */
-#if (1 << HARDIRQ_BITS) < NR_IRQS
+#if (1 << HARDIRQ_BITS) < MAX_HARDIRQS_PER_CPU
 # error HARDIRQ_BITS is too low!
 #endif
 #endif
@@ -67,12 +72,30 @@
 #define in_softirq()           (softirq_count())
 #define in_interrupt()         (irq_count())
 
-#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
-# define in_atomic()   ((preempt_count() & ~PREEMPT_ACTIVE) != kernel_locked())
+#if defined(CONFIG_PREEMPT)
+# define PREEMPT_INATOMIC_BASE kernel_locked()
+# define PREEMPT_CHECK_OFFSET 1
 #else
-# define in_atomic()   ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
+# define PREEMPT_INATOMIC_BASE 0
+# define PREEMPT_CHECK_OFFSET 0
 #endif
 
+/*
+ * Are we running in atomic context?  WARNING: this macro cannot
+ * always detect atomic context; in particular, it cannot know about
+ * held spinlocks in non-preemptible kernels.  Thus it should not be
+ * used in the general case to determine whether sleeping is possible.
+ * Do not use in_atomic() in driver code.
+ */
+#define in_atomic()    ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
+
+/*
+ * Check whether we were atomic before we did preempt_disable():
+ * (used by the scheduler, *after* releasing the kernel lock)
+ */
+#define in_atomic_preempt_off() \
+               ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
+
 #ifdef CONFIG_PREEMPT
 # define preemptible() (preempt_count() == 0 && !irqs_disabled())
 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
@@ -87,25 +110,60 @@ extern void synchronize_irq(unsigned int irq);
 # define synchronize_irq(irq)  barrier()
 #endif
 
-#define nmi_enter()            irq_enter()
-#define nmi_exit()             sub_preempt_count(HARDIRQ_OFFSET)
+struct task_struct;
 
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
-static inline void account_user_vtime(struct task_struct *tsk)
-{
-}
-
 static inline void account_system_vtime(struct task_struct *tsk)
 {
 }
 #endif
 
-#define irq_enter()                                    \
+#if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU)
+extern void rcu_irq_enter(void);
+extern void rcu_irq_exit(void);
+extern void rcu_nmi_enter(void);
+extern void rcu_nmi_exit(void);
+#else
+# define rcu_irq_enter() do { } while (0)
+# define rcu_irq_exit() do { } while (0)
+# define rcu_nmi_enter() do { } while (0)
+# define rcu_nmi_exit() do { } while (0)
+#endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU) */
+
+/*
+ * It is safe to do non-atomic ops on ->hardirq_context,
+ * because NMI handlers may not preempt and the ops are
+ * always balanced, so the interrupted value of ->hardirq_context
+ * will always be restored.
+ */
+#define __irq_enter()                                  \
        do {                                            \
                account_system_vtime(current);          \
                add_preempt_count(HARDIRQ_OFFSET);      \
+               trace_hardirq_enter();                  \
+       } while (0)
+
+/*
+ * Enter irq context (on NO_HZ, update jiffies):
+ */
+extern void irq_enter(void);
+
+/*
+ * Exit irq context without processing softirqs:
+ */
+#define __irq_exit()                                   \
+       do {                                            \
+               trace_hardirq_exit();                   \
+               account_system_vtime(current);          \
+               sub_preempt_count(HARDIRQ_OFFSET);      \
        } while (0)
 
+/*
+ * Exit irq context and process softirqs if needed:
+ */
 extern void irq_exit(void);
 
+#define nmi_enter()            do { lockdep_off(); rcu_nmi_enter(); __irq_enter(); } while (0)
+#define nmi_exit()             do { __irq_exit(); rcu_nmi_exit(); lockdep_on(); } while (0)
+
 #endif /* LINUX_HARDIRQ_H */