From 06e8d3db4922d4048e42e6c7b3ca15252a2f1231 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Thu, 22 May 2008 00:22:16 -0400
Subject: [PATCH] --- yaml --- r: 100555 b: refs/heads/master c:
 19384c0314342222b18d4c7f09cdce1ca74dfd2a h: refs/heads/master i:   100553:
 488e052077f1569896fb23f39de52062a1b2fd72   100551:
 b90ee0d0d723e876b836c8b85e10cc4015198d54 v: v3

---
 [refs]                              |  2 +-
 trunk/kernel/trace/trace.c          | 32 +++++++++++++++++++++--------
 trunk/kernel/trace/trace_selftest.c |  1 +
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/[refs] b/[refs]
index 278cec9bfb8b..a521f376e4d3 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c6531cce6e6e4b99bcda46b6268d6f2d9e30aea4
+refs/heads/master: 19384c0314342222b18d4c7f09cdce1ca74dfd2a
diff --git a/trunk/kernel/trace/trace.c b/trunk/kernel/trace/trace.c
index 3271916ff033..0567f51bbea4 100644
--- a/trunk/kernel/trace/trace.c
+++ b/trunk/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/trunk/kernel/trace/trace_selftest.c b/trunk/kernel/trace/trace_selftest.c
index 3877dd9102f1..18c5423bc977 100644
--- a/trunk/kernel/trace/trace_selftest.c
+++ b/trunk/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;