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authorRussell King <rmk+kernel@arm.linux.org.uk>2010-07-10 10:10:18 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-07-10 10:53:13 +0100
commitac78884e6d89714d18b32b5b7d574116ecfb7c88 (patch)
tree4e2d9d3106f10f5ce7ae3c9469444cab8ec75024 /arch/arm/kernel/entry-armv.S
parentd9e38040ccf9eb06b9b41c393c512ceb23f51a7f (diff)
downloadlinux-linaro-stable-ac78884e6d89714d18b32b5b7d574116ecfb7c88.tar.gz
ARM: lockdep: fix unannotated irqs-on
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) Fix this by ensuring that the lockdep interrupt state is manipulated in the appropriate places. We essentially treat userspace as an entirely separate environment which isn't relevant to lockdep (lockdep doesn't monitor userspace.) We don't tell lockdep that IRQs will be enabled in that environment. Instead, when creating kernel threads (which is a rare event compared to entering/leaving userspace) we have to update the lockdep state. Do this by starting threads with IRQs disabled, and in the kthread helper, tell lockdep that IRQs are enabled, and enable them. This provides lockdep with a consistent view of the current IRQ state in kernel space. This also revert portions of 0d928b0b616d1c5c5fe76019a87cba171ca91633 which didn't fix the problem. Tested-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
-rw-r--r--arch/arm/kernel/entry-armv.S16
1 files changed, 6 insertions, 10 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 7ee48e7f8f31..3fd7861de4d1 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -162,8 +162,6 @@ ENDPROC(__und_invalid)
@ r4 - orig_r0 (see pt_regs definition in ptrace.h)
@
stmia r5, {r0 - r4}
-
- asm_trace_hardirqs_off
.endm
.align 5
@@ -204,7 +202,7 @@ __dabt_svc:
@
@ IRQs off again before pulling preserved data off the stack
@
- disable_irq
+ disable_irq_notrace
@
@ restore SPSR and restart the instruction
@@ -218,6 +216,9 @@ ENDPROC(__dabt_svc)
__irq_svc:
svc_entry
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
#ifdef CONFIG_PREEMPT
get_thread_info tsk
ldr r8, [tsk, #TI_PREEMPT] @ get preempt count
@@ -291,7 +292,7 @@ __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
@@ -327,7 +328,7 @@ __pabt_svc:
@
@ IRQs off again before pulling preserved data off the stack
@
- disable_irq
+ disable_irq_notrace
@
@ restore SPSR and restart the instruction
@@ -393,8 +394,6 @@ ENDPROC(__pabt_svc)
@ Clear FP to mark the first stack frame
@
zero_fp
-
- asm_trace_hardirqs_off
.endm
.macro kuser_cmpxchg_check
@@ -465,9 +464,6 @@ __irq_usr:
THUMB( movne r0, #0 )
THUMB( strne r0, [r0] )
#endif
-#ifdef CONFIG_TRACE_IRQFLAGS
- bl trace_hardirqs_on
-#endif
mov why, #0
b ret_to_user