fault_inject: Don't rely on "return value" from WRITE_ONCE()

It's a bit weird that WRITE_ONCE() evaluates to the value it stores and
it's different to smp_store_release(), which can't be used this way.

In preparation for preventing this in WRITE_ONCE(), change the fault
injection code to use a local variable instead.

Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 8186ca8..ce12621 100644 (file)
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -106,7 +106,9 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
                unsigned int fail_nth = READ_ONCE(current->fail_nth);
 
                if (fail_nth) {
-                       if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
+                       fail_nth--;
+                       WRITE_ONCE(current->fail_nth, fail_nth);
+                       if (!fail_nth)
                                goto fail;
 
                        return false;