[PATCH v3 04/12] fault_inject: Don't rely on "return value" from WRITE_ONCE()

From: Will Deacon
Date: Wed Apr 15 2020 - 12:53:23 EST


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@xxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
lib/fault-inject.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 8186ca84910b..ce12621b4275 100644
--- 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;
--
2.26.0.110.g2183baf09c-goog