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Commit 4787c368 authored by Seiji Aguchi's avatar Seiji Aguchi Committed by Ingo Molnar
Browse files

x86/tracing: Add irq_enter/exit() in smp_trace_reschedule_interrupt() 



Reschedule vector tracepoints may be called in cpu idle state.
This causes lockdep check warning below.

The tracepoint requires rcu but for accuracy it also
requires irq_enter() (tracepoints record the irq context), thus,
the tracepoint interrupt handler should be calling irq_enter()
and not rcu_irq_enter() (irq_enter() calls rcu_irq_enter()).

So, add irq_enter/exit() to smp_trace_reschedule_interrupt()
with common pre/post processing functions, smp_entering_irq()
and exiting_irq() (exiting_irq() calls just irq_exit()
 in arch/x86/include/asm/apic.h),
because these can be shared among reschedule, call_function,
and call_function_single vectors.

[   50.720557] Testing event reschedule_exit:
[   50.721349]
[   50.721502] ===============================
[   50.721835] [ INFO: suspicious RCU usage. ]
[   50.722169] 3.10.0-rc6-00004-gcf910e8 #190 Not tainted
[   50.722582] -------------------------------
[   50.722915] /c/kernel-tests/src/linux/arch/x86/include/asm/trace/irq_vectors.h:50 suspicious rcu_dereference_check() usage!
[   50.723770]
[   50.723770] other info that might help us debug this:
[   50.723770]
[   50.724385]
[   50.724385] RCU used illegally from idle CPU!
[   50.724385] rcu_scheduler_active = 1, debug_locks = 0
[   50.725232] RCU used illegally from extended quiescent state!
[   50.725690] no locks held by swapper/0/0.
[   50.726010]
[   50.726010] stack backtrace:
[...]

Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/51CDCFA3.9080101@hds.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5236eb96

arch/x86/kernel/smp.c

+18 −11
Original line number Diff line number Diff line
@@ -265,23 +265,30 @@ void smp_reschedule_interrupt(struct pt_regs *regs) 
	 */

}



void smp_trace_reschedule_interrupt(struct pt_regs *regs)

static inline void smp_entering_irq(void)

{

	ack_APIC_irq();

	irq_enter();

}



void smp_trace_reschedule_interrupt(struct pt_regs *regs)

{

	/*

	 * Need to call irq_enter() before calling the trace point.

	 * __smp_reschedule_interrupt() calls irq_enter/exit() too (in

	 * scheduler_ipi(). This is OK, since those functions are allowed

	 * to nest.

	 */

	smp_entering_irq();

	trace_reschedule_entry(RESCHEDULE_VECTOR);

	__smp_reschedule_interrupt();

	trace_reschedule_exit(RESCHEDULE_VECTOR);

	exiting_irq();

	/*

	 * KVM uses this interrupt to force a cpu out of guest mode

	 */

}



static inline void call_function_entering_irq(void)

{

	ack_APIC_irq();

	irq_enter();

}



static inline void __smp_call_function_interrupt(void)

{

	generic_smp_call_function_interrupt();
@@ -290,14 +297,14 @@ static inline void __smp_call_function_interrupt(void) 


void smp_call_function_interrupt(struct pt_regs *regs)

{

	call_function_entering_irq();

	smp_entering_irq();

	__smp_call_function_interrupt();

	exiting_irq();

}



void smp_trace_call_function_interrupt(struct pt_regs *regs)

{

	call_function_entering_irq();

	smp_entering_irq();

	trace_call_function_entry(CALL_FUNCTION_VECTOR);

	__smp_call_function_interrupt();

	trace_call_function_exit(CALL_FUNCTION_VECTOR);
@@ -312,14 +319,14 @@ static inline void __smp_call_function_single_interrupt(void) 


void smp_call_function_single_interrupt(struct pt_regs *regs)

{

	call_function_entering_irq();

	smp_entering_irq();

	__smp_call_function_single_interrupt();

	exiting_irq();

}



void smp_trace_call_function_single_interrupt(struct pt_regs *regs)

{

	call_function_entering_irq();

	smp_entering_irq();

	trace_call_function_single_entry(CALL_FUNCTION_SINGLE_VECTOR);

	__smp_call_function_single_interrupt();

	trace_call_function_single_exit(CALL_FUNCTION_SINGLE_VECTOR);