[PATCH] lockdep: print irq-trace info on asserts
When we print an assert due to scheduling-in-atomic bugs, and if lockdep
is enabled, then the IRQ tracing information of lockdep can be printed
to pinpoint the code location that disabled interrupts. This saved me
quite a bit of debugging time in cases where the backtrace did not
identify the irq-disabling site well enough.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 498bfbd..ea097dd 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -281,15 +281,25 @@
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
extern void early_init_irq_lock_class(void);
#else
-# define early_init_irq_lock_class() do { } while (0)
+static inline void early_init_irq_lock_class(void)
+{
+}
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
extern void early_boot_irqs_off(void);
extern void early_boot_irqs_on(void);
+extern void print_irqtrace_events(struct task_struct *curr);
#else
-# define early_boot_irqs_off() do { } while (0)
-# define early_boot_irqs_on() do { } while (0)
+static inline void early_boot_irqs_off(void)
+{
+}
+static inline void early_boot_irqs_on(void)
+{
+}
+static inline void print_irqtrace_events(struct task_struct *curr)
+{
+}
#endif
/*
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 69e92c6..07a3d74 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1447,7 +1447,7 @@
return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
}
-static inline void print_irqtrace_events(struct task_struct *curr)
+void print_irqtrace_events(struct task_struct *curr)
{
printk("irq event stamp: %u\n", curr->irq_events);
printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
@@ -1460,10 +1460,6 @@
print_ip_sym(curr->softirq_disable_ip);
}
-#else
-static inline void print_irqtrace_events(struct task_struct *curr)
-{
-}
#endif
static int
diff --git a/kernel/sched.c b/kernel/sched.c
index 8a0afb9..5cd833b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3429,6 +3429,8 @@
"%s/0x%08x/%d\n",
current->comm, preempt_count(), current->pid);
debug_show_held_locks(current);
+ if (irqs_disabled())
+ print_irqtrace_events(current);
dump_stack();
}
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
@@ -6977,6 +6979,8 @@
printk("in_atomic():%d, irqs_disabled():%d\n",
in_atomic(), irqs_disabled());
debug_show_held_locks(current);
+ if (irqs_disabled())
+ print_irqtrace_events(current);
dump_stack();
}
#endif