locking/qspinlock: Fix 'wait_early' set but not used warning

Waiman-Long · ingomolnar · commit ca4bc2e07b71 · 2024-02-28T13:08:37.000+01:00
When CONFIG_LOCK_EVENT_COUNTS is off, the wait_early variable will be set but not used. This is expected. Recent compilers will not generate wait_early code in this case. Add the __maybe_unused attribute to wait_early for suppressing this W=1 warning. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20240222150540.79981-2-longman@redhat.com Closes: https://lore.kernel.org/oe-kbuild-all/202312260422.f4pK3f9m-lkp@intel.com/
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
@@ -294,8 +294,8 @@ 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;
 	int loop;
-	bool wait_early;
 
 	for (;;) {
 		for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) {

Original file line number	Diff line number	Diff line change
`@@ -294,8 +294,8 @@ static void pv_wait_node(struct mcs_spinlock node, struct mcs_spinlock prev)`
`294`	`294`	`{`
`295`	`295`	`struct pv_node pn = (struct pv_node )node;`
`296`	`296`	`struct pv_node pp = (struct pv_node )prev;`
	`297`	`+ bool __maybe_unused wait_early;`
`297`	`298`	`int loop;`
`298`		`- bool wait_early;`
`299`	`299`
`300`	`300`	`for (;;) {`
`301`	`301`	`for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) {`