[PATCH] lockdep: annotate kprobes irq fiddling

[PATCH] lockdep: annotate kprobes irq fiddling

[Peter Zijlstra]

Hi,

The below patch fixes a lockdep error in 2.6.23-rc9 when using tcp_probe.

---

Subject: lockdep: annotate kprobes irq fiddling

kprobes disables irqs for jprobes, but does not tell lockdep about it.

CC: Prasanna S Panchamukhi <prasanna@in.ibm.com>
CC: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
CC: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
CC: David S. Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/i386/kernel/kprobes.c   |    8 ++++++++
 arch/x86_64/kernel/kprobes.c |    8 ++++++++
 2 files changed, 16 insertions(+)

Index: linux-2.6-2/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6-2.orig/arch/i386/kernel/kprobes.c
+++ linux-2.6-2/arch/i386/kernel/kprobes.c
@@ -558,6 +558,13 @@ static int __kprobes post_kprobe_handler
 
 	resume_execution(cur, regs, kcb);
 	regs->eflags |= kcb->kprobe_saved_eflags;
+#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
+	if (raw_irqs_disabled_flags(regs->eflags)) {
+		trace_hardirqs_off();
+	} else {
+		trace_hardirqs_on();
+	}
+#endif
 
 	/*Restore back the original saved kprobes variables and continue. */
 	if (kcb->kprobe_status == KPROBE_REENTER) {
@@ -695,6 +702,7 @@ int __kprobes setjmp_pre_handler(struct 
 	memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
 			MIN_STACK_SIZE(addr));
 	regs->eflags &= ~IF_MASK;
+	trace_hardirqs_off();
 	regs->eip = (unsigned long)(jp->entry);
 	return 1;
 }
Index: linux-2.6-2/arch/x86_64/kernel/kprobes.c
===================================================================
--- linux-2.6-2.orig/arch/x86_64/kernel/kprobes.c
+++ linux-2.6-2/arch/x86_64/kernel/kprobes.c
@@ -545,6 +545,13 @@ int __kprobes post_kprobe_handler(struct
 
 	resume_execution(cur, regs, kcb);
 	regs->eflags |= kcb->kprobe_saved_rflags;
+#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
+	if (raw_irqs_disabled_flags(regs->eflags)) {
+		trace_hardirqs_off();
+	} else {
+		trace_hardirqs_on();
+	}
+#endif
 
 	/* Restore the original saved kprobes variables and continue. */
 	if (kcb->kprobe_status == KPROBE_REENTER) {
@@ -685,6 +692,7 @@ int __kprobes setjmp_pre_handler(struct 
 	memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
 			MIN_STACK_SIZE(addr));
 	regs->eflags &= ~IF_MASK;
+	trace_hardirqs_off();
 	regs->rip = (unsigned long)(jp->entry);
 	return 1;
 }

Re: [PATCH] lockdep: annotate kprobes irq fiddling

[Ingo Molnar]

* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> Hi,
> 
> The below patch fixes a lockdep error in 2.6.23-rc9 when using 
> tcp_probe.
> 
> ---
> 
> Subject: lockdep: annotate kprobes irq fiddling
> 
> kprobes disables irqs for jprobes, but does not tell lockdep about it.

this resolves this warning during an allyesconfig bzImage bootup test:

 [  423.670337] WARNING: at kernel/lockdep.c:2658 check_flags()
 [  423.670341]  [<c0107f01>] show_trace_log_lvl+0x19/0x2e
 [  423.670348]  [<c0107ffa>] show_trace+0x12/0x14
 [  423.670350]  [<c0108010>] dump_stack+0x14/0x16
 [  423.670353]  [<c015249d>] check_flags+0x95/0x142
 [  423.670357]  [<c0155576>] lock_acquire+0x52/0xb8
 [  423.670360]  [<c1313c90>] _spin_lock+0x2e/0x58
 [  423.670365]  [<c11b72f9>] jtcp_rcv_established+0x6e/0x189
 [  423.670369]  [<c11810da>] tcp_v4_do_rcv+0x30b/0x620
 [  423.670373]  [<c1181c8c>] tcp_v4_rcv+0x89d/0x8fa
 [  423.670376]  [<c1167dba>] ip_local_deliver+0x17d/0x225
 [  423.670380]  [<c11682f5>] ip_rcv+0x493/0x4ce
 [  423.670383]  [<c11177ef>] netif_receive_skb+0x347/0x365
 [  423.670388]  [<c07b6e7b>] nv_napi_poll+0x501/0x6c3
 [  423.670393]  [<c1115b1a>] net_rx_action+0xa3/0x1b6
 [  423.670396]  [<c013bdee>] __do_softirq+0x76/0xfb
 [  423.670400]  [<c0109189>] do_softirq+0x75/0xf3

	Ingo