linux-kernel - Re: [PATCH] locking/rtmutex: Add the missing 'ES' of macro CONFIG_DEBUG_RT

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Date:   Tue, 10 Aug 2021 09:47:21 +0800
From:   Boqun Feng <boqun.feng@...il.com>
To:     "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
Cc:     Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Waiman Long <longman@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] locking/rtmutex: Add the missing 'ES' of macro
 CONFIG_DEBUG_RT_MUTEXES

On Tue, Aug 10, 2021 at 09:21:15AM +0800, Leizhen (ThunderTown) wrote:
> 
> 
> On 2021/8/9 22:41, Will Deacon wrote:
> > On Sat, Jul 31, 2021 at 08:30:11PM +0800, Zhen Lei wrote:
> >> The build option name is defined as DEBUG_RT_MUTEXES in lib/Kconfig.debug,
> >> commit f41dcc18698e ("locking/rtmutex: Move debug functions as inlines
> >> into common header") can also corroborate this.
> >>
> >> Fixes: f7efc4799f81 ("locking/rtmutex: Inline chainwalk depth check")
> >> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> >> ---
> >>  kernel/locking/rtmutex.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> >> index b5d9bb5202c6..ad0db322ed3b 100644
> >> --- a/kernel/locking/rtmutex.c
> >> +++ b/kernel/locking/rtmutex.c
> >> @@ -343,7 +343,7 @@ static __always_inline bool
> >>  rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter,
> >>  			      enum rtmutex_chainwalk chwalk)
> >>  {
> >> -	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEX))
> >> +	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
> >>  		return waiter != NULL;
> >>  	return chwalk == RT_MUTEX_FULL_CHAINWALK;
> > 
> > Oops, yes. How did you find this?
> 
> I found it by chance. When locating a futex problem, I was confused when
> reading this part of the code. I used "git grep -wn CONFIG_DEBUG_RT_MUTEX"
> to search for the implementation in other places. But I found that it was
> not used in other places, then I checked the patch history and found it.
> 

FWIW, script/checkkconfigsymbols.py can be used to detect usage of
undefined CONFIG_*, Zhouyi Zhou used it to find a few cases in RCU
recently:

	https://lore.kernel.org/lkml/CAABZP2wuWtGAGRqWJb3Gewm5VLZdZ_C=LRZsFbaG3jcQabO3qA@mail.gmail.com/

And thanks for the fix:

Acked-by: Boqun Feng <boqun.feng@...il.com>

Regards,
Boqun

> > 
> > Acked-by: Will Deacon <will@...nel.org>
> > 
> > Will
> > .
> >