ftrace: fix locking

we can hold all cpu trace buffer locks at once - put each into a
separate lock class.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 4 insertions, 5 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a40687a4413a..b3811ca74071 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1865,11 +1865,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 
         }
 
-        for_each_possible_cpu(cpu) {
+        for_each_cpu_mask(cpu, mask) {
                 data = iter->tr->data[cpu];
-
-                if (!cpu_isset(cpu, mask))
-                        continue;
                 spin_unlock(&data->lock);
                 atomic_dec(&data->disabled);
         }
@@ -2076,6 +2073,7 @@ static int trace_alloc_page(void)
         for_each_possible_cpu(i) {
                 data = global_trace.data[i];
                 spin_lock_init(&data->lock);
+                lockdep_set_class(&data->lock, &data->lock_key);
                 page = list_entry(pages.next, struct page, lru);
                 list_del_init(&page->lru);
                 list_add_tail(&page->lru, &data->trace_pages);
@@ -2084,6 +2082,7 @@ static int trace_alloc_page(void)
 #ifdef CONFIG_TRACER_MAX_TRACE
                 data = max_tr.data[i];
                 spin_lock_init(&data->lock);
+                lockdep_set_class(&data->lock, &data->lock_key);
                 page = list_entry(pages.next, struct page, lru);
                 list_del_init(&page->lru);
                 list_add_tail(&page->lru, &data->trace_pages);
@@ -2203,5 +2202,4 @@ __init static int tracer_alloc_buffers(void)
         }
         return ret;
 }
-
 fs_initcall(tracer_alloc_buffers);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 29a7ea59de50..b0408356f0e0 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -56,6 +56,7 @@ struct trace_array_cpu {
         struct list_head        trace_pages;
         atomic_t                disabled;
         spinlock_t              lock;
+        struct lock_class_key   lock_key;
         cycle_t                 time_offset;
 
         /* these fields get copied into max-trace: */