lockdep: Fix trace_hardirqs_on_caller()
Peter Zijlstra [Tue, 26 Jul 2011 11:13:44 +0000 (13:13 +0200)]
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>

kernel/lockdep.c

index 3956f51..74ca247 100644 (file)
@@ -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;