[PATCH] fault-inject: fix wrong should_fail() decision in task context

[Akinobu Mita <akinobu.mita@gmail.com>]

Commit 1203c8e6fb0a ("fault-inject: simplify access check for fail-nth")
unintentionally broke a conditional statement in should_fail().  Any faults
are not injected in the task context by the change when the systematic
fault injection is not used.

This change restores to the previous correct behaviour.

Fixes: 1203c8e6fb0a ("fault-inject: simplify access check for fail-nth")
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reported-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 lib/fault-inject.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 7d315fd..cf7b129 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -110,10 +110,12 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
 	if (in_task()) {
 		unsigned int fail_nth = READ_ONCE(current->fail_nth);
 
-		if (fail_nth && !WRITE_ONCE(current->fail_nth, fail_nth - 1))
-			goto fail;
+		if (fail_nth) {
+			if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
+				goto fail;
 
-		return false;
+			return false;
+		}
 	}
 
 	/* No need to check any other properties if the probability is 0 */
-- 
2.7.4