[RESEND PATCH] ARM: fix 'unannotated irqs-on' lockdep warning
From: tom . leiming
Date: Sun May 23 2010 - 07:50:25 EST
From: Ming Lei <tom.leiming@xxxxxxxxx>
This patch fixes the 'unannotated irqs-on' lockdep warning[1]:
This patch introduces macro of trace_ret_hardirqs_on, which will
call trace_hardirqs_on if I flag in the stored CPSR is zero.
In the path of returning to user-space, the patch replaces disable_irq
with disable_irq_notrace in ret_to_user to avoid the 'unannotated irqs-on'
lockdep warning since hardirqs is always enabled before returning to user.
In the path of returning to kernel-space, the patch still replaces
disable_irq with disable_irq_notrace in __xxx_svc handler and adds
trace_hardirqs_on before calling svc_exit to trace the possible hardirqs on
event for avoiding the possible 'unannotated irqs-on' lockdep warning.
The patch not only fixes the warning[1] to make lockdep usable on ARM,
but also improves the efficiency if lockdep is enabled:
- remove one calling for asm_trace_hardirqs_on before returning
to user-space
- convert asm_trace_hardirqs_on to trace_hardirqs_on in the
path of returning to kernel space from exception and __only__ call it if
harirqs will be enabled before returning.
[1]
CPU: Testing write buffer coherency: ok
------------[ cut here ]------------
WARNING: at kernel/lockdep.c:3145 check_flags+0xcc/0x1dc()
Modules linked in:
[<c0035120>] (unwind_backtrace+0x0/0xf8) from [<c0355374>] (dump_stack+0x20/0x24)
[<c0355374>] (dump_stack+0x20/0x24) from [<c0060c04>] (warn_slowpath_common+0x58/0x70)
[<c0060c04>] (warn_slowpath_common+0x58/0x70) from [<c0060c3c>] (warn_slowpath_null+0x20/0x24)
[<c0060c3c>] (warn_slowpath_null+0x20/0x24) from [<c008f224>] (check_flags+0xcc/0x1dc)
[<c008f224>] (check_flags+0xcc/0x1dc) from [<c00945dc>] (lock_acquire+0x50/0x140)
[<c00945dc>] (lock_acquire+0x50/0x140) from [<c0358434>] (_raw_spin_lock+0x50/0x88)
[<c0358434>] (_raw_spin_lock+0x50/0x88) from [<c00fd114>] (set_task_comm+0x2c/0x60)
[<c00fd114>] (set_task_comm+0x2c/0x60) from [<c007e184>] (kthreadd+0x30/0x108)
[<c007e184>] (kthreadd+0x30/0x108) from [<c0030104>] (kernel_thread_exit+0x0/0x8)
---[ end trace 1b75b31a2719ed1c ]---
possible reason: unannotated irqs-on.
irq event stamp: 3
hardirqs last enabled at (2): [<c0059bb0>] finish_task_switch+0x48/0xb0
hardirqs last disabled at (3): [<c002f0b0>] ret_slow_syscall+0xc/0x1c
softirqs last enabled at (0): [<c005f3e0>] copy_process+0x394/0xe5c
softirqs last disabled at (0): [<(null)>] (null)
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
arch/arm/kernel/entry-armv.S | 31 +++++++++++++++++--------------
arch/arm/kernel/entry-common.S | 2 +-
arch/arm/kernel/entry-header.S | 7 +++++++
3 files changed, 25 insertions(+), 15 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 7ee48e7..42d33cf 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -204,13 +204,15 @@ __dabt_svc:
@
@ IRQs off again before pulling preserved data off the stack
@
- disable_irq
+ disable_irq_notrace
@
@ restore SPSR and restart the instruction
+ @ trace possible hardirqs on event before returning
@
- ldr r2, [sp, #S_PSR]
- svc_exit r2 @ return from exception
+ ldr r4, [sp, #S_PSR]
+ trace_ret_hardirqs_on r4
+ svc_exit r4 @ return from exception
UNWIND(.fnend )
ENDPROC(__dabt_svc)
@@ -235,10 +237,7 @@ __irq_svc:
blne svc_preempt
#endif
ldr r4, [sp, #S_PSR] @ irqs are already disabled
-#ifdef CONFIG_TRACE_IRQFLAGS
- tst r4, #PSR_I_BIT
- bleq trace_hardirqs_on
-#endif
+ trace_ret_hardirqs_on r4
svc_exit r4 @ return from exception
UNWIND(.fnend )
ENDPROC(__irq_svc)
@@ -291,13 +290,15 @@ __und_svc:
@
@ IRQs off again before pulling preserved data off the stack
@
-1: disable_irq
+1: disable_irq_notrace
@
@ restore SPSR and restart the instruction
+ @ trace possible hardirqs on event before returning
@
- ldr r2, [sp, #S_PSR] @ Get SVC cpsr
- svc_exit r2 @ return from exception
+ ldr r4, [sp, #S_PSR] @ Get SVC cpsr
+ trace_ret_hardirqs_on r4
+ svc_exit r4 @ return from exception
UNWIND(.fnend )
ENDPROC(__und_svc)
@@ -327,13 +328,15 @@ __pabt_svc:
@
@ IRQs off again before pulling preserved data off the stack
@
- disable_irq
+ disable_irq_notrace
@
@ restore SPSR and restart the instruction
- @
- ldr r2, [sp, #S_PSR]
- svc_exit r2 @ return from exception
+ @ trace possible hardirqs on event before returning
+ @
+ ldr r4, [sp, #S_PSR]
+ trace_ret_hardirqs_on r4
+ svc_exit r4 @ return from exception
UNWIND(.fnend )
ENDPROC(__pabt_svc)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 2c1db77..ed471a7 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -58,7 +58,7 @@ work_resched:
*/
ENTRY(ret_to_user)
ret_slow_syscall:
- disable_irq @ disable interrupts
+ disable_irq_notrace @ disable interrupts
ldr r1, [tsk, #TI_FLAGS]
tst r1, #_TIF_WORK_MASK
bne work_pending
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index d93f976..ac51ce3 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -30,6 +30,13 @@
#error "Please fix"
#endif
+ .macro trace_ret_hardirqs_on, rspsr
+#ifdef CONFIG_TRACE_IRQFLAGS
+ tst \rspsr, #PSR_I_BIT
+ bleq trace_hardirqs_on
+#endif
+ .endm
+
.macro zero_fp
#ifdef CONFIG_FRAME_POINTER
mov fp, #0
--
1.6.2.5
--
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