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Date: Wed, 15 Feb 2012 12:36:26 +0800
From: Ming Lei <tom.leiming@...il.com>
To: Christoph Lameter <cl@...ux.com>, Tejun Heo <tj@...nel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: linux-kernel@...r.kernel.org, Ming Lei <tom.leiming@...il.com>
Subject: [PATCH v1] percpu: use raw_local_irq_* in _this_cpu op
It doesn't make sense to trace irq off or do irq flags
lock proving inside 'this_cpu' operations, so replace local_irq_*
with raw_local_irq_* in 'this_cpu' op.
Also the patch fixes onelockdep warning[1] by the replacement, see
below:
In commit: 933393f58fef9963eac61db8093689544e29a600(percpu:
Remove irqsafe_cpu_xxx variants), local_irq_save/restore(flags) are
added inside this_cpu_inc operation, so that trace_hardirqs_off_caller
will be called by trace_hardirqs_on_caller directly because
__debug_atomic_inc is implemented as this_cpu_inc, which may trigger
the lockdep warning[1], for example in the below ARM scenary:
kernel_thread_helper /*irq disabled*/
->trace_hardirqs_on_caller /*hardirqs_enabled was set*/
->trace_hardirqs_off_caller /*hardirqs_enabled cleared*/
__this_cpu_add(redundant_hardirqs_on)
->trace_hardirqs_off_caller /*irq disabled, so call here*/
The 'unannotated irqs-on' warning will be triggered somewhere because
irq is just enabled after the irq trace in kernel_thread_helper.
[1],
[ 0.162841] ------------[ cut here ]------------
[ 0.167694] WARNING: at kernel/lockdep.c:3493 check_flags+0xc0/0x1d0()
[ 0.174468] Modules linked in:
[ 0.177703] Backtrace:
[ 0.180328] [<c00171f0>] (dump_backtrace+0x0/0x110) from [<c0412320>] (dump_stack+0x18/0x1c)
[ 0.189086] r6:c051f778 r5:00000da5 r4:00000000 r3:60000093
[ 0.195007] [<c0412308>] (dump_stack+0x0/0x1c) from [<c00410e8>] (warn_slowpath_common+0x54/0x6c)
[ 0.204223] [<c0041094>] (warn_slowpath_common+0x0/0x6c) from [<c0041124>] (warn_slowpath_null+0x24/0x2c)
[ 0.214111] r8:00000000 r7:00000000 r6:ee069598 r5:60000013 r4:ee082000
[ 0.220825] r3:00000009
[ 0.223693] [<c0041100>] (warn_slowpath_null+0x0/0x2c) from [<c0088f38>] (check_flags+0xc0/0x1d0)
[ 0.232910] [<c0088e78>] (check_flags+0x0/0x1d0) from [<c008d348>] (lock_acquire+0x4c/0x11c)
[ 0.241668] [<c008d2fc>] (lock_acquire+0x0/0x11c) from [<c0415aa4>] (_raw_spin_lock+0x3c/0x74)
[ 0.250610] [<c0415a68>] (_raw_spin_lock+0x0/0x74) from [<c010a844>] (set_task_comm+0x20/0xc0)
[ 0.259521] r6:ee069588 r5:ee0691c0 r4:ee082000
[ 0.264404] [<c010a824>] (set_task_comm+0x0/0xc0) from [<c0060780>] (kthreadd+0x28/0x108)
[ 0.272857] r8:00000000 r7:00000013 r6:c0044a08 r5:ee0691c0 r4:ee082000
[ 0.279571] r3:ee083fe0
[ 0.282470] [<c0060758>] (kthreadd+0x0/0x108) from [<c0044a08>] (do_exit+0x0/0x6dc)
[ 0.290405] r5:c0060758 r4:00000000
[ 0.294189] ---[ end trace 1b75b31a2719ed1c ]---
[ 0.299041] possible reason: unannotated irqs-on.
[ 0.303955] irq event stamp: 5
[ 0.307159] hardirqs last enabled at (4): [<c001331c>] no_work_pending+0x8/0x2c
[ 0.314880] hardirqs last disabled at (5): [<c0089b08>] trace_hardirqs_on_caller+0x60/0x26c
[ 0.323547] softirqs last enabled at (0): [<c003f754>] copy_process+0x33c/0xef4
[ 0.331207] softirqs last disabled at (0): [< (null)>] (null)
[ 0.337585] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Acked-by: Christoph Lameter <cl@...ux.com>
Signed-off-by: Ming Lei <tom.leiming@...il.com>
---
include/linux/percpu.h | 20 ++++++++++----------
1 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 6e68d05..5ed1e38 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -294,9 +294,9 @@ do { \
#define _this_cpu_generic_to_op(pcp, val, op) \
do { \
unsigned long flags; \
- local_irq_save(flags); \
+ raw_local_irq_save(flags); \
*__this_cpu_ptr(&(pcp)) op val; \
- local_irq_restore(flags); \
+ raw_local_irq_restore(flags); \
} while (0)
#ifndef this_cpu_write
@@ -395,10 +395,10 @@ do { \
({ \
typeof(pcp) ret__; \
unsigned long flags; \
- local_irq_save(flags); \
+ raw_local_irq_save(flags); \
__this_cpu_add(pcp, val); \
ret__ = __this_cpu_read(pcp); \
- local_irq_restore(flags); \
+ raw_local_irq_restore(flags); \
ret__; \
})
@@ -425,10 +425,10 @@ do { \
#define _this_cpu_generic_xchg(pcp, nval) \
({ typeof(pcp) ret__; \
unsigned long flags; \
- local_irq_save(flags); \
+ raw_local_irq_save(flags); \
ret__ = __this_cpu_read(pcp); \
__this_cpu_write(pcp, nval); \
- local_irq_restore(flags); \
+ raw_local_irq_restore(flags); \
ret__; \
})
@@ -453,11 +453,11 @@ do { \
({ \
typeof(pcp) ret__; \
unsigned long flags; \
- local_irq_save(flags); \
+ raw_local_irq_save(flags); \
ret__ = __this_cpu_read(pcp); \
if (ret__ == (oval)) \
__this_cpu_write(pcp, nval); \
- local_irq_restore(flags); \
+ raw_local_irq_restore(flags); \
ret__; \
})
@@ -490,10 +490,10 @@ do { \
({ \
int ret__; \
unsigned long flags; \
- local_irq_save(flags); \
+ raw_local_irq_save(flags); \
ret__ = __this_cpu_generic_cmpxchg_double(pcp1, pcp2, \
oval1, oval2, nval1, nval2); \
- local_irq_restore(flags); \
+ raw_local_irq_restore(flags); \
ret__; \
})
--
1.7.9
--
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