2 files changed, 24 insertions, 9 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3271916ff033..0567f51bbea4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -249,24 +249,32 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
         tracing_record_cmdline(current);
 }
 
+#define CHECK_COND(cond)                        \
+        if (unlikely(cond)) {                   \
+                tracing_disabled = 1;           \
+                WARN_ON(1);                     \
+                return -1;                      \
+        }
+
 /**
  * check_pages - integrity check of trace buffers
  *
  * As a safty measure we check to make sure the data pages have not
- * been corrupted. TODO: configure to disable this because it adds
- * a bit of overhead.
+ * been corrupted.
  */
-void check_pages(struct trace_array_cpu *data)
+int check_pages(struct trace_array_cpu *data)
 {
         struct page *page, *tmp;
 
-        BUG_ON(data->trace_pages.next->prev != &data->trace_pages);
-        BUG_ON(data->trace_pages.prev->next != &data->trace_pages);
+        CHECK_COND(data->trace_pages.next->prev != &data->trace_pages);
+        CHECK_COND(data->trace_pages.prev->next != &data->trace_pages);
 
         list_for_each_entry_safe(page, tmp, &data->trace_pages, lru) {
-                BUG_ON(page->lru.next->prev != &page->lru);
-                BUG_ON(page->lru.prev->next != &page->lru);
+                CHECK_COND(page->lru.next->prev != &page->lru);
+                CHECK_COND(page->lru.prev->next != &page->lru);
         }
+
+        return 0;
 }
 
 /**
@@ -280,7 +288,6 @@ void *head_page(struct trace_array_cpu *data)
 {
         struct page *page;
 
-        check_pages(data);
         if (list_empty(&data->trace_pages))
                 return NULL;
 
@@ -2566,7 +2573,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 {
         unsigned long val;
         char buf[64];
-        int ret;
+        int i, ret;
 
         if (cnt >= sizeof(buf))
                 return -EINVAL;
@@ -2635,8 +2642,15 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
                         trace_free_page();
         }
 
+        /* check integrity */
+        for_each_tracing_cpu(i)
+                check_pages(global_trace.data[i]);
+
         filp->f_pos += cnt;
 
+        /* If check pages failed, return ENOMEM */
+        if (tracing_disabled)
+                cnt = -ENOMEM;
  out:
         max_tr.entries = global_trace.entries;
         mutex_unlock(&trace_types_lock);
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 3877dd9102f1..18c5423bc977 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -28,6 +28,7 @@ trace_test_buffer_cpu(struct trace_array *tr, struct trace_array_cpu *data)
         page = list_entry(data->trace_pages.next, struct page, lru);
         entries = page_address(page);
 
+        check_pages(data);
         if (head_page(data) != entries)
                 goto failed;