mirror of
https://github.com/adulau/aha.git
synced 2024-12-29 12:16:20 +00:00
2232c2d8e0
The PREEMPT-RCU can get stuck if a CPU goes idle and NO_HZ is set. The idle CPU will not progress the RCU through its grace period and a synchronize_rcu my get stuck. Without this patch I have a box that will not boot when PREEMPT_RCU and NO_HZ are set. That same box boots fine with this patch. This patch comes from the -rt kernel where it has been tested for several months. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
158 lines
4.1 KiB
C
158 lines
4.1 KiB
C
#ifndef LINUX_HARDIRQ_H
|
|
#define LINUX_HARDIRQ_H
|
|
|
|
#include <linux/preempt.h>
|
|
#include <linux/smp_lock.h>
|
|
#include <linux/lockdep.h>
|
|
#include <asm/hardirq.h>
|
|
#include <asm/system.h>
|
|
|
|
/*
|
|
* We put the hardirq and softirq counter into the preemption
|
|
* counter. The bitmask has the following meaning:
|
|
*
|
|
* - bits 0-7 are the preemption count (max preemption depth: 256)
|
|
* - bits 8-15 are the softirq count (max # of softirqs: 256)
|
|
*
|
|
* The hardirq count can be overridden per architecture, the default is:
|
|
*
|
|
* - bits 16-27 are the hardirq count (max # of hardirqs: 4096)
|
|
* - ( bit 28 is the PREEMPT_ACTIVE flag. )
|
|
*
|
|
* PREEMPT_MASK: 0x000000ff
|
|
* SOFTIRQ_MASK: 0x0000ff00
|
|
* HARDIRQ_MASK: 0x0fff0000
|
|
*/
|
|
#define PREEMPT_BITS 8
|
|
#define SOFTIRQ_BITS 8
|
|
|
|
#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) < MAX_HARDIRQS_PER_CPU
|
|
# error HARDIRQ_BITS is too low!
|
|
#endif
|
|
#endif
|
|
|
|
#define PREEMPT_SHIFT 0
|
|
#define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)
|
|
#define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
|
|
|
|
#define __IRQ_MASK(x) ((1UL << (x))-1)
|
|
|
|
#define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
|
|
#define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
|
|
#define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
|
|
|
|
#define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT)
|
|
#define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT)
|
|
#define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT)
|
|
|
|
#if PREEMPT_ACTIVE < (1 << (HARDIRQ_SHIFT + HARDIRQ_BITS))
|
|
#error PREEMPT_ACTIVE is too low!
|
|
#endif
|
|
|
|
#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
|
|
#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
|
|
#define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK))
|
|
|
|
/*
|
|
* Are we doing bottom half or hardware interrupt processing?
|
|
* Are we in a softirq context? Interrupt context?
|
|
*/
|
|
#define in_irq() (hardirq_count())
|
|
#define in_softirq() (softirq_count())
|
|
#define in_interrupt() (irq_count())
|
|
|
|
#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
# define PREEMPT_CHECK_OFFSET 1
|
|
#else
|
|
# define PREEMPT_CHECK_OFFSET 0
|
|
#endif
|
|
|
|
/*
|
|
* Check whether we were atomic before we did preempt_disable():
|
|
* (used by the scheduler)
|
|
*/
|
|
#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)
|
|
#else
|
|
# define preemptible() 0
|
|
# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
extern void synchronize_irq(unsigned int irq);
|
|
#else
|
|
# define synchronize_irq(irq) barrier()
|
|
#endif
|
|
|
|
struct task_struct;
|
|
|
|
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
|
|
static inline void account_system_vtime(struct task_struct *tsk)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#if defined(CONFIG_PREEMPT_RCU) && defined(CONFIG_NO_HZ)
|
|
extern void rcu_irq_enter(void);
|
|
extern void rcu_irq_exit(void);
|
|
#else
|
|
# define rcu_irq_enter() do { } while (0)
|
|
# define rcu_irq_exit() do { } while (0)
|
|
#endif /* CONFIG_PREEMPT_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 { \
|
|
rcu_irq_enter(); \
|
|
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); \
|
|
rcu_irq_exit(); \
|
|
} while (0)
|
|
|
|
/*
|
|
* Exit irq context and process softirqs if needed:
|
|
*/
|
|
extern void irq_exit(void);
|
|
|
|
#define nmi_enter() do { lockdep_off(); __irq_enter(); } while (0)
|
|
#define nmi_exit() do { __irq_exit(); lockdep_on(); } while (0)
|
|
|
|
#endif /* LINUX_HARDIRQ_H */
|