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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 0d928b0b61
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>
This commit is contained in:
Russell King 2010-07-10 10:10:18 +01:00
parent d9e38040cc
commit ac78884e6d
2 changed files with 20 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
arch/arm/kernel/entry-armv.S
View File

@ -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

23
arch/arm/kernel/process.c
View File

@ -351,17 +351,21 @@ EXPORT_SYMBOL(dump_fpu);
/*
* Shuffle the argument into the correct register before calling the
* thread function. r1 is the thread argument, r2 is the pointer to
* the thread function, and r3 points to the exit function.
* thread function. r4 is the thread argument, r5 is the pointer to
* the thread function, and r6 points to the exit function.
*/
extern void kernel_thread_helper(void);
asm( ".pushsection .text\n"
" .align\n"
" .type kernel_thread_helper, #function\n"
"kernel_thread_helper:\n"
" mov r0, r1\n"
" mov lr, r3\n"
" mov pc, r2\n"
#ifdef CONFIG_TRACE_IRQFLAGS
" bl trace_hardirqs_on\n"
#endif
" msr cpsr_c, r7\n"
" mov r0, r4\n"
" mov lr, r6\n"
" mov pc, r5\n"
" .size kernel_thread_helper, . - kernel_thread_helper\n"
" .popsection");
@ -391,11 +395,12 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
memset(&regs, 0, sizeof(regs));
regs.ARM_r1 = (unsigned long)arg;
regs.ARM_r2 = (unsigned long)fn;
regs.ARM_r3 = (unsigned long)kernel_thread_exit;
regs.ARM_r4 = (unsigned long)arg;
regs.ARM_r5 = (unsigned long)fn;
regs.ARM_r6 = (unsigned long)kernel_thread_exit;
regs.ARM_r7 = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;
regs.ARM_pc = (unsigned long)kernel_thread_helper;
regs.ARM_cpsr = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;
regs.ARM_cpsr = regs.ARM_r7 | PSR_I_BIT;
return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}