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From: Peter Zijlstra <peterz@infradead.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org, ath10k@lists.infradead.org,
	mingo@redhat.com, Shuah Khan <skhan@linuxfoundation.org>,
	kuba@kernel.org, will@kernel.org, davem@davemloft.net,
	kvalo@codeaurora.org
Subject: Re: [PATCH 1/2] lockdep: add lockdep_assert_not_held()
Date: Mon, 15 Feb 2021 17:04:10 +0100	[thread overview]
Message-ID: <YCqbehyyeUoL0pPT@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <79aeb83a288051bd3a2a3f15e5ac42e06f154d48.camel@sipsolutions.net>

On Mon, Feb 15, 2021 at 02:12:30PM +0100, Johannes Berg wrote:
> On Mon, 2021-02-15 at 11:44 +0100, Peter Zijlstra wrote:
> > 
> > I think something like so will work, but please double check.
> 
> Yeah, that looks better.
> 
> > +++ b/include/linux/lockdep.h
> > @@ -294,11 +294,15 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
> >  
> >  #define lockdep_depth(tsk)	(debug_locks ? (tsk)->lockdep_depth : 0)
> >  
> > -#define lockdep_assert_held(l)	do {				\
> > -		WARN_ON(debug_locks && !lockdep_is_held(l));	\
> > +#define lockdep_assert_held(l)	do {					\
> > +		WARN_ON(debug_locks && lockdep_is_held(l) == 0));	\
> >  	} while (0)
> 
> That doesn't really need to change? It's the same.

Correct, but I found it more symmetric vs the not implementation below.

> > -#define lockdep_assert_held_write(l)	do {			\
> > +#define lockdep_assert_not_held(l)	do {				\
> > +		WARN_ON(debug_locks && lockdep_is_held(l) == 1));	\
> > +	} while (0)
> > +
> > +#define lockdep_assert_held_write(l)	do {				\
> >  		WARN_ON(debug_locks && !lockdep_is_held_type(l, 0));	\
> >  	} while (0)
> >  
> > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> > index c1418b47f625..983ba206f7b2 100644
> > --- a/kernel/locking/lockdep.
> > +++ b/kernel/locking/lockdep.c
> > @@ -5467,7 +5467,7 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
> >  	int ret = 0;
> >  
> >  	if (unlikely(!lockdep_enabled()))
> > -		return 1; /* avoid false negative lockdep_assert_held() */
> > +		return -1; /* avoid false negative lockdep_assert_held() */
> 
> Maybe add lockdep_assert_not_held() to the comment, to explain the -1
> (vs non-zero)?

Yeah, or frob a '*' in there.

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  reply	other threads:[~2021-02-15 16:05 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-12 23:28 [PATCH 0/2] Add lockdep_assert_not_held() Shuah Khan
2021-02-12 23:28 ` [PATCH 1/2] lockdep: add lockdep_assert_not_held() Shuah Khan
2021-02-14 17:53   ` Peter Zijlstra
2021-02-15 10:44     ` Peter Zijlstra
2021-02-15 13:12       ` Johannes Berg
2021-02-15 16:04         ` Peter Zijlstra [this message]
2021-02-15 16:10           ` Johannes Berg
2021-02-22 20:51             ` Shuah Khan
2021-02-12 23:28 ` [PATCH 2/2] ath10k: detect conf_mutex held ath10k_drain_tx() calls Shuah Khan
2021-02-14  6:08   ` Kalle Valo

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