From 9b4fb5cec031f81ef436bf2cfd9fc265e25f6e45 Mon Sep 17 00:00:00 2001
From: Will Deacon <will@kernel.org>
Date: Thu, 19 Dec 2019 17:40:21 +0000
Subject: [PATCH] fault_inject: Don't rely on "return value" from WRITE_ONCE()
References: jsc#SLE-15848
Patch-mainline: v5.8-rc1
Git-commit: 9b4fb5cec031f81ef436bf2cfd9fc265e25f6e45
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>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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;
--
2.26.2