Commit 59bc300b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

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



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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.359433429@infradead.org
parent fd501d4f

arch/x86/include/asm/idtentry.h

+0 −2
Original line number Diff line number Diff line
@@ -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);				\

}									\

kernel/softirq.c

+14 −7
Original line number Diff line number Diff line
@@ -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();

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