[PATCH] lockdep: irqtrace subsystem, core

Accurate hard-IRQ-flags and softirq-flags state tracing.

This allows us to attach extra functionality to IRQ flags on/off
events (such as trace-on/off).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 1cd46a4fb0d3..b7db7fb74f53 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -968,6 +968,10 @@ static task_t *copy_process(unsigned long clone_flags,
         if (!p)
                 goto fork_out;
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+        DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
+        DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
+#endif
         retval = -EAGAIN;
         if (atomic_read(&p->user->processes) >=
                         p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
@@ -1042,6 +1046,21 @@ static task_t *copy_process(unsigned long clone_flags,
         }
         mpol_fix_fork_child_flag(p);
 #endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+        p->irq_events = 0;
+        p->hardirqs_enabled = 0;
+        p->hardirq_enable_ip = 0;
+        p->hardirq_enable_event = 0;
+        p->hardirq_disable_ip = _THIS_IP_;
+        p->hardirq_disable_event = 0;
+        p->softirqs_enabled = 1;
+        p->softirq_enable_ip = _THIS_IP_;
+        p->softirq_enable_event = 0;
+        p->softirq_disable_ip = 0;
+        p->softirq_disable_event = 0;
+        p->hardirq_context = 0;
+        p->softirq_context = 0;
+#endif
 
         rt_mutex_init_task(p);