perf_counter: fix the output lock

[mv-sheeva.git] / kernel / perf_counter.c

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 2d13427383051fdb2fa421be6ecfd787aff34452..c881afef997b94c1c2b9fcb05c6c3a3e2cfb8996 100644 (file)
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1409,6 +1409,7 @@ static int perf_mmap_data_alloc(struct perf_counter *counter, int nr_pages)
        }
 
        data->nr_pages = nr_pages;
+       atomic_set(&data->lock, -1);
 
        rcu_assign_pointer(counter->data, data);
 
@@ -1755,7 +1756,7 @@ static void perf_output_lock(struct perf_output_handle *handle)
        if (in_nmi() && atomic_read(&data->lock) == cpu)
                return;
 
-       while (atomic_cmpxchg(&data->lock, 0, cpu) != 0)
+       while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
                cpu_relax();
 
        handle->locked = 1;
@@ -1784,7 +1785,7 @@ again:
         * NMI can happen here, which means we can miss a done_head update.
         */
 
-       cpu = atomic_xchg(&data->lock, 0);
+       cpu = atomic_xchg(&data->lock, -1);
        WARN_ON_ONCE(cpu != smp_processor_id());
 
        /*
@@ -1794,7 +1795,7 @@ again:
                /*
                 * Since we had it locked, we can lock it again.
                 */
-               while (atomic_cmpxchg(&data->lock, 0, cpu) != 0)
+               while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
                        cpu_relax();
 
                goto again;