[tip: locking/core] locking/ww-mutex: Fix uninitialized use of ret in test_aa()

[tip-bot2 for Nathan Chancellor]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     1415b49bcd321bca7347f43f8b269c91ec46d1dc
Gitweb:        https://git.kernel.org/tip/1415b49bcd321bca7347f43f8b269c91ec46d1dc
Author:        Nathan Chancellor <nathan@xxxxxxxxxx>
AuthorDate:    Wed, 22 Sep 2021 07:58:22 -07:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 01 Oct 2021 13:57:49 +02:00

locking/ww-mutex: Fix uninitialized use of ret in test_aa()

Clang warns:

kernel/locking/test-ww_mutex.c:138:7: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
                if (!ww_mutex_trylock(&mutex, &ctx)) {
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/locking/test-ww_mutex.c:172:9: note: uninitialized use occurs here
        return ret;
               ^~~
kernel/locking/test-ww_mutex.c:138:3: note: remove the 'if' if its condition is always false
                if (!ww_mutex_trylock(&mutex, &ctx)) {
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/locking/test-ww_mutex.c:125:9: note: initialize the variable 'ret' to silence this warning
        int ret;
               ^
                = 0
1 error generated.

Assign !ww_mutex_trylock(...) to ret so that it is always initialized.

Fixes: 12235da8c80a ("kernel/locking: Add context to ww_mutex_trylock()")
Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx>
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Waiman Long <longman@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210922145822.3935141-1-nathan@xxxxxxxxxx
---
 kernel/locking/test-ww_mutex.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index d63ac41..3530041 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -135,7 +135,8 @@ static int test_aa(bool trylock)
 			goto out;
 		}
 	} else {
-		if (!ww_mutex_trylock(&mutex, &ctx)) {
+		ret = !ww_mutex_trylock(&mutex, &ctx);
+		if (ret) {
 			pr_err("%s: initial trylock failed!\n", __func__);
 			goto out;
 		}