[BUG] Error in copy_process, when enable CONFIG_PROVE_LOCKING.

Commit Message

Matt Fleming June 27, 2009, 11:22 a.m. UTC

On Tue, May 12, 2009 at 01:15:22PM +0100, Stuart MENEFY wrote:
> Nobuhiro Iwamatsu wrote:
> > Error in copy_process, when enable CONFIG_PROVE_LOCKING.
> > This error has p->hardirqs_enabled in kernel.fork.c
> > 
> >  987 #ifdef CONFIG_PROVE_LOCKING
> >  988     DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
> >  989     DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
> >  990 #endif
> >  991     retval = -EAGAIN;
> > 
> > The error message is as follows.
> > I am debuging this. Please teach if you know the revision method of
> > this problem.
> 
> As it happens I was looking at this recently. I think there are some
> missing calls to trace_hardirqs_on/off in the assembly
> code. Unfortunately my kernel is quite different from the mainline in
> this area, but you could try this patch which is an *untested* forward
> port of the code I'm currently running successfully.
> 

Stuart, I took your patch and applied it to 2.6.31-rc1 and reworked it
until it stopped crashing qemu. I've attached the patch, can you just
give it a once over to make sure that nothing seems broken? It boots
fine with and without CONFIG_PREEMPT.

Paul, Nobuhiro, can you please test the attached patch to make sure that
it gets rid of the lockdep warnings and doesn't deadlock your machines?

I'll respin this patch into a proper series once everyone's happy with
it.

Patch

diff --git a/arch/sh/include/asm/entry-macros.S b/arch/sh/include/asm/entry-macros.S
index 3a4752a..0f0d4b4 100644
--- a/arch/sh/include/asm/entry-macros.S
+++ b/arch/sh/include/asm/entry-macros.S
@@ -31,6 +31,78 @@ 
 #endif	
 	.endm
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+	.macro	TRACE_IRQS_ON
+	mov.l	r0, @-r15
+	mov.l	r1, @-r15
+	mov.l	r2, @-r15
+	mov.l	r3, @-r15
+	mov.l	r4, @-r15
+	mov.l	r5, @-r15
+	mov.l	r6, @-r15
+	mov.l	r7, @-r15
+
+	mov.l   7834f, r0
+	jsr	@r0
+	 nop
+	
+	mov.l	@r15+, r7
+	mov.l	@r15+, r6
+	mov.l	@r15+, r5
+	mov.l	@r15+, r4
+	mov.l	@r15+, r3
+	mov.l	@r15+, r2
+	mov.l	@r15+, r1
+	mov.l	@r15+, r0
+	mov.l	7834f, r0
+	
+	bra	7835f
+	 nop
+	.balign	4
+7834:	.long	trace_hardirqs_on
+7835:
+	.endm
+	.macro	TRACE_IRQS_OFF
+	
+	mov.l	r0, @-r15
+	mov.l	r1, @-r15
+	mov.l	r2, @-r15
+	mov.l	r3, @-r15
+	mov.l	r4, @-r15
+	mov.l	r5, @-r15
+	mov.l	r6, @-r15
+	mov.l	r7, @-r15
+	
+	mov.l	7834f, r0
+	jsr	@r0
+	 nop
+
+	mov.l	@r15+, r7
+	mov.l	@r15+, r6
+	mov.l	@r15+, r5
+	mov.l	@r15+, r4
+	mov.l	@r15+, r3
+	mov.l	@r15+, r2
+	mov.l	@r15+, r1
+	mov.l	@r15+, r0
+	mov.l	7834f, r0
+	
+	bra	7835f
+	 nop
+	.balign	4
+7834:	.long	trace_hardirqs_off
+7835:
+	.endm
+
+#else
+	.macro	TRACE_IRQS_ON
+	.endm
+
+	.macro	TRACE_IRQS_OFF
+	.endm
+#endif
+
 #if defined(CONFIG_CPU_SH2A) || defined(CONFIG_CPU_SH4)
 # define PREF(x)	pref	@x
 #else
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index d62359c..30cfbed 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -45,7 +45,7 @@ 
  */
 
 #if defined(CONFIG_PREEMPT)
-#  define preempt_stop()	cli
+#  define preempt_stop()	cli ; TRACE_IRQS_OFF
 #else
 #  define preempt_stop()
 #  define resume_kernel		__restore_all
@@ -55,11 +55,7 @@ 
 	.align	2
 ENTRY(exception_error)
 	!
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	2f, r0
-	jsr	@r0
-	 nop
-#endif
+	TRACE_IRQS_ON
 	sti
 	mov.l	1f, r0
 	jmp	@r0
@@ -67,22 +63,23 @@  ENTRY(exception_error)
 
 	.align	2
 1:	.long	do_exception_error
-#ifdef CONFIG_TRACE_IRQFLAGS
-2:	.long	trace_hardirqs_on
-#endif
 
 	.align	2
 ret_from_exception:
 	preempt_stop()
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	4f, r0
-	jsr	@r0
-	 nop
-#endif
 ENTRY(ret_from_irq)
 	!
 	mov	#OFF_SR, r0
 	mov.l	@(r0,r15), r0	! get status register
+	
+	shlr2	r0
+	and	#0x3c, r0
+	cmp/eq	#0x3c, r0
+	bt	9f
+	TRACE_IRQS_ON
+9:
+	mov	#OFF_SR, r0
+	mov.l	@(r0,r15), r0	! get status register
 	shll	r0
 	shll	r0		! kernel space?
 	get_current_thread_info r8, r0
@@ -125,11 +122,7 @@  noresched:
 ENTRY(resume_userspace)
 	! r8: current_thread_info
 	cli
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	5f, r0
-	jsr	@r0
-	 nop
-#endif
+	TRACE_IRQS_OfF
 	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
 	tst	#_TIF_WORK_MASK, r0
 	bt/s	__restore_all
@@ -156,11 +149,7 @@  work_resched:
 	jsr	@r1				! schedule
 	 nop
 	cli
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	5f, r0
-	jsr	@r0
-	 nop
-#endif
+	TRACE_IRQS_OFF
 	!
 	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
 	tst	#_TIF_WORK_MASK, r0
@@ -172,10 +161,6 @@  work_resched:
 1:	.long	schedule
 2:	.long	do_notify_resume
 3:	.long	resume_userspace
-#ifdef CONFIG_TRACE_IRQFLAGS
-4:	.long	trace_hardirqs_on
-5:	.long	trace_hardirqs_off
-#endif
 
 	.align	2
 syscall_exit_work:
@@ -184,11 +169,7 @@  syscall_exit_work:
 	tst	#_TIF_WORK_SYSCALL_MASK, r0
 	bt/s	work_pending
 	 tst	#_TIF_NEED_RESCHED, r0
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	5f, r0
-	jsr	@r0
-	 nop
-#endif
+	TRACE_IRQS_ON
 	sti
 	mov	r15, r4
 	mov.l	8f, r0			! do_syscall_trace_leave
@@ -321,11 +302,7 @@  ENTRY(system_call)
 	bt/s	debug_trap		! it's a debug trap..
 	 nop
 
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	5f, r10
-	jsr	@r10
-	 nop
-#endif
+	TRACE_IRQS_ON
 	sti
 
 	!
@@ -351,11 +328,7 @@  syscall_call:
 	!
 syscall_exit:
 	cli
-#ifdef CONFIG_TRACE_IRQFLAGS
-	mov.l	6f, r0
-	jsr	@r0
-	 nop
-#endif
+	TRACE_IRQS_OFF
 	!
 	get_current_thread_info r8, r0
 	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
@@ -369,9 +342,5 @@  syscall_exit:
 #endif
 2:	.long	NR_syscalls
 3:	.long	sys_call_table
-#ifdef CONFIG_TRACE_IRQFLAGS
-5:	.long	trace_hardirqs_on
-6:	.long	trace_hardirqs_off
-#endif
 7:	.long	do_syscall_trace_enter
 8:	.long	do_syscall_trace_leave
diff --git a/arch/sh/kernel/io_trapped.c b/arch/sh/kernel/io_trapped.c
index 77dfecb..e27a19e 100644
--- a/arch/sh/kernel/io_trapped.c
+++ b/arch/sh/kernel/io_trapped.c
@@ -112,14 +112,15 @@  void __iomem *match_trapped_io_handler(struct list_head *list,
 	struct trapped_io *tiop;
 	struct resource *res;
 	int k, len;
+	unsigned long flags;
 
-	spin_lock_irq(&trapped_lock);
+	spin_lock_irqsave(&trapped_lock, flags);
 	list_for_each_entry(tiop, list, list) {
 		voffs = 0;
 		for (k = 0; k < tiop->num_resources; k++) {
 			res = tiop->resource + k;
 			if (res->start == offset) {
-				spin_unlock_irq(&trapped_lock);
+				spin_unlock_irqrestore(&trapped_lock, flags);
 				return tiop->virt_base + voffs;
 			}
 
@@ -127,7 +128,7 @@  void __iomem *match_trapped_io_handler(struct list_head *list,
 			voffs += roundup(len, PAGE_SIZE);
 		}
 	}
-	spin_unlock_irq(&trapped_lock);
+	spin_unlock_irqrestore(&trapped_lock, flags);
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(match_trapped_io_handler);
diff --git a/drivers/serial/sh-sci.c b/drivers/serial/sh-sci.c
index 66f5267..879eb6c 100644
--- a/drivers/serial/sh-sci.c
+++ b/drivers/serial/sh-sci.c
@@ -662,10 +662,11 @@  static irqreturn_t sci_rx_interrupt(int irq, void *port)
 static irqreturn_t sci_tx_interrupt(int irq, void *ptr)
 {
 	struct uart_port *port = ptr;
+	unsigned long flags;
 
-	spin_lock_irq(&port->lock);
+	spin_lock_irqsave(&port->lock, flags);
 	sci_transmit_chars(port);
-	spin_unlock_irq(&port->lock);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return IRQ_HANDLED;
 }