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x86/entry: Clarify irq_{enter,exit}_rcu()

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Because:

  irq_enter_rcu() includes lockdep_hardirq_enter()
  irq_exit_rcu() does *NOT* include lockdep_hardirq_exit()

Which resulted in two 'stray' lockdep_hardirq_exit() calls in
idtentry.h, and me spending a long time trying to find the matching
enter calls.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.359433429@infradead.org
This commit is contained in:
Peter Zijlstra 2020-05-29 23:27:39 +02:00 committed by Thomas Gleixner
parent fd501d4f03
commit 59bc300b71
2 changed files with 14 additions and 9 deletions
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2
arch/x86/include/asm/idtentry.h
View File

@ -206,7 +206,6 @@ __visible noinstr void func(struct pt_regs *regs, \
kvm_set_cpu_l1tf_flush_l1d(); \
__##func (regs, (u8)error_code); \
irq_exit_rcu(); \
lockdep_hardirq_exit(); \
instrumentation_end(); \
idtentry_exit_cond_rcu(regs, rcu_exit); \
} \
@ -249,7 +248,6 @@ __visible noinstr void func(struct pt_regs *regs) \
kvm_set_cpu_l1tf_flush_l1d(); \
run_on_irqstack_cond(__##func, regs, regs); \
irq_exit_rcu(); \
lockdep_hardirq_exit(); \
instrumentation_end(); \
idtentry_exit_cond_rcu(regs, rcu_exit); \
} \

21
kernel/softirq.c
View File

@ -404,12 +404,7 @@ static inline void tick_irq_exit(void)
#endif
}
/**
* irq_exit_rcu() - Exit an interrupt context without updating RCU
*
* Also processes softirqs if needed and possible.
*/
void irq_exit_rcu(void)
static inline void __irq_exit_rcu(void)
{
#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
local_irq_disable();
@ -424,6 +419,18 @@ void irq_exit_rcu(void)
tick_irq_exit();
}
/**
* irq_exit_rcu() - Exit an interrupt context without updating RCU
*
* Also processes softirqs if needed and possible.
*/
void irq_exit_rcu(void)
{
__irq_exit_rcu();
/* must be last! */
lockdep_hardirq_exit();
}
/**
* irq_exit - Exit an interrupt context, update RCU and lockdep
*
@ -431,7 +438,7 @@ void irq_exit_rcu(void)
*/
void irq_exit(void)
{
irq_exit_rcu();
__irq_exit_rcu();
rcu_irq_exit();
/* must be last! */
lockdep_hardirq_exit();