[PATCH 4/4 -next] fault-injection: make stacktrace filter works as expected

[Wei Yongjun <weiyongjun1@huawei.com>]

stacktrace filter is checked after others, such as fail-nth,
interval and probability. This make it doesn't work well as
expected.

Fix to running stacktrace filter before other filters. It will
speed up fault inject testing for driver modules.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
---
 lib/fault-inject.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index deca05e7c9b3..9dd1dd1d2610 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -105,10 +105,16 @@ static inline bool fail_stacktrace(struct fault_attr *attr)
 
 bool should_fail(struct fault_attr *attr, ssize_t size)
 {
+	bool stack_checked = false;
+
 	if (in_task()) {
 		unsigned int fail_nth = READ_ONCE(current->fail_nth);
 
 		if (fail_nth) {
+			if (!fail_stacktrace(attr))
+				return false;
+
+			stack_checked = true;
 			fail_nth--;
 			WRITE_ONCE(current->fail_nth, fail_nth);
 			if (!fail_nth)
@@ -128,6 +134,9 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
 	if (atomic_read(&attr->times) == 0)
 		return false;
 
+	if (!stack_checked && !fail_stacktrace(attr))
+		return false;
+
 	if (atomic_read(&attr->space) > size) {
 		atomic_sub(size, &attr->space);
 		return false;
@@ -142,9 +151,6 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
 	if (attr->probability <= prandom_u32() % 100)
 		return false;
 
-	if (!fail_stacktrace(attr))
-		return false;
-
 fail:
 	fail_dump(attr);
 
-- 
2.34.1