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Date: Fri, 28 Jun 2013 14:02:11 -0400
From: Seiji Aguchi <seiji.aguchi@....com>
To: linux-kernel@...r.kernel.org, x86@...nel.org, rostedt@...dmis.org,
hpa@...or.com
CC: mingo@...e.hu, tglx@...utronix.de
Subject: [PATCH -tip] x86,trace: 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:
[ 50.726359] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.0-rc6-00004-gcf910e8 #190
[ 50.726965] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 50.727417] 00000001 00000001 79c53f04 798bd9f9 79c53f2c 79077a70 79b412c6 79b41fd1
[ 50.728159] 00000001 00000000 79c5ef8c 87147c58 00000000 79c55800 79c53f38 79010b65
[ 50.728849] 79c52000 79c53f7c 798c720e 79c52000 79c5ef8c 00000004 00000000 79c55800
[ 50.729532] Call Trace:
[ 50.729730] [<798bd9f9>] dump_stack+0x16/0x18
[ 50.730072] [<79077a70>] lockdep_rcu_suspicious+0xf2/0xfa
[ 50.730498] [<79010b65>] smp_trace_reschedule_interrupt+0x1c8/0x1d0
[ 50.730979] [<798c720e>] trace_reschedule_interrupt+0x36/0x3c
[ 50.731214] [<7901875f>] ? native_safe_halt+0x5/0x7
[ 50.731214] [<790085cc>] default_idle+0xb1/0x1e2
[ 50.731214] [<79008d05>] arch_cpu_idle+0xe/0x10
[ 50.731214] [<79069ddf>] cpu_startup_entry+0x1e4/0x2c3
[ 50.731214] [<798adb34>] rest_init+0x12c/0x132
[ 50.731214] [<798ada08>] ? __read_lock_failed+0x14/0x14
[ 50.731214] [<79d309e4>] start_kernel+0x38d/0x393
[ 50.731214] [<79d30489>] ? repair_env_string+0x51/0x51
[ 50.731214] [<79d302c3>] i386_start_kernel+0x79/0x7d
[ 50.771947] OK
[ 50.772099] Testing event reschedule_entry: OK
Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
---
arch/x86/kernel/smp.c | 29 ++++++++++++++++++-----------
1 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index f4fe0b8..cdaa347 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -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);
--
1.7.1
--
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