locking/qspinlock: Always evaluate lockevent* non-event parameter once

The 'inc' parameter of lockevent_add() and the cond parameter of lockevent_cond_inc() are only evaluated when CONFIG_LOCK_EVENT_COUNTS is on. That can cause problem if those parameters are expressions with side effect like a "++". Fix this by evaluating those non-event parameters once even if CONFIG_LOCK_EVENT_COUNTS is off. This will also eliminate the need of the __maybe_unused attribute to the wait_early local variable in pv_wait_node(). Suggested-by: Ingo Molnar <[email protected]> Signed-off-by: Waiman Long <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Reviewed-by: Boqun Feng <[email protected]> Link: https://lore.kernel.org/r/[email protected]
mpe · Mar 21, 2024 · 3774b28 · 3774b28
1 parent 4ae3dc8
commit 3774b28
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Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/kernel/locking/lock_events.h b/kernel/locking/lock_events.h
@@ -53,8 +53,8 @@ static inline void __lockevent_add(enum lock_events event, int inc)
 #else  /* CONFIG_LOCK_EVENT_COUNTS */
 
 #define lockevent_inc(ev)
-#define lockevent_add(ev, c)
-#define lockevent_cond_inc(ev, c)
+#define lockevent_add(ev, c)		do { (void)(c); } while (0)
+#define lockevent_cond_inc(ev, c)	do { (void)(c); } while (0)
 
 #endif /* CONFIG_LOCK_EVENT_COUNTS */
 

diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
@@ -294,7 +294,7 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
 {
 	struct pv_node *pn = (struct pv_node *)node;
 	struct pv_node *pp = (struct pv_node *)prev;
-	bool __maybe_unused wait_early;
+	bool wait_early;
 	int loop;
 
 	for (;;) {