lockdep: Fix trace_hardirqs_on_caller()

Commit dd4e5d3ac4a ("lockdep: Fix trace_[soft,hard]irqs_[on,off]()
recursion") made a bit of a mess of the various checks and error
conditions.

In particular it moved the check for !irqs_disabled() before the
spurious enable test, resulting in some warnings.

Reported-by: Arnaud Lacombe <lacombar@gmail.com>
Reported-by: Dave Jones <davej@redhat.com>
Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1311679697.24752.28.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 14 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 3956f5149e25..74ca247a4d4f 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2485,23 +2485,9 @@ static void __trace_hardirqs_on_caller(unsigned long ip)
 {
         struct task_struct *curr = current;
 
-        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
-                return;
-
-        if (unlikely(curr->hardirqs_enabled)) {
-                /*
-                 * Neither irq nor preemption are disabled here
-                 * so this is racy by nature but losing one hit
-                 * in a stat is not a big deal.
-                 */
-                __debug_atomic_inc(redundant_hardirqs_on);
-                return;
-        }
         /* we'll do an OFF -> ON transition: */
         curr->hardirqs_enabled = 1;
 
-        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
-                return;
         /*
          * We are going to turn hardirqs on, so set the
          * usage bit for all held locks:
@@ -2529,9 +2515,25 @@ void trace_hardirqs_on_caller(unsigned long ip)
         if (unlikely(!debug_locks || current->lockdep_recursion))
                 return;
 
+        if (unlikely(current->hardirqs_enabled)) {
+                /*
+                 * Neither irq nor preemption are disabled here
+                 * so this is racy by nature but losing one hit
+                 * in a stat is not a big deal.
+                 */
+                __debug_atomic_inc(redundant_hardirqs_on);
+                return;
+        }
+
         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
                 return;
 
+        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
+                return;
+
+        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+                return;
+
         current->lockdep_recursion = 1;
         __trace_hardirqs_on_caller(ip);
         current->lockdep_recursion = 0;