[PATCH 2/2] lockdep reentrancy

Mathieu Desnoyers
2007-01-16T17:56:35Z

Here is a patch to lockdep.c so it behaves correctly when a kprobe breakpoint is
put on a marker within hardirq tracing functions as long as the marker is within
the lockdep_recursion incremented boundaries. It should apply on
2.6.20-rc4-git3.

Mathieu

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

@@ -1841,33 +1843,36 @@ void trace_hardirqs_on(void)
struct task_struct *curr = current;
unsigned long ip;

if (unlikely(!debug_locks || current->lockdep_recursion))
return;

+ current->lockdep_recursion++;
+ barrier();
+
if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
- return;
+ goto end;

if (unlikely(curr->hardirqs_enabled)) {
debug_atomic_inc(&redundant_hardirqs_on);
- return;
+ goto end;
}
/* we'll do an OFF -> ON transition: */
curr->hardirqs_enabled = 1;
ip = (unsigned long) __builtin_return_address(0);

if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
- return;
+ goto end;
if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
- return;
+ goto end;
/*
* We are going to turn hardirqs on, so set the
* usage bit for all held locks:
*/
if (!mark_held_locks(curr, 1, ip))
- return;
+ goto end;
/*
* If we have softirqs enabled, then set the usage
* bit for all held locks. (disabled hardirqs prevented
@@ -1875,11 +1880,14 @@ void trace_hardirqs_on(void)
*/
if (curr->softirqs_enabled)
if (!mark_held_locks(curr, 0, ip))
- return;
+ goto end;

curr->hardirq_enable_ip = ip;
curr->hardirq_enable_event = ++curr->irq_events;
debug_atomic_inc(&hardirqs_on_events);
+end:
+ barrier();
+ current->lockdep_recursion--;
}

EXPORT_SYMBOL(trace_hardirqs_on);
@@ -1888,14 +1896,17 @@ void trace_hardirqs_off(void)
{
struct task_struct *curr = current;

if (unlikely(!debug_locks || current->lockdep_recursion))
return;

+ current->lockdep_recursion++;
+ barrier();
+
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
- return;
+ goto end;

if (curr->hardirqs_enabled) {
/*
@@ -1910,6 +1921,9 @@ void trace_hardirqs_off(void)
debug_atomic_inc(&hardirqs_off_events);
} else
debug_atomic_inc(&redundant_hardirqs_off);
+end:
+ barrier();
+ current->lockdep_recursion--;
}

EXPORT_SYMBOL(trace_hardirqs_off);

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