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From: Peter Zijlstra <peterz@infradead.org>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: mingo@redhat.com, will@kernel.org, kvalo@codeaurora.org,
	davem@davemloft.net, kuba@kernel.org, ath10k@lists.infradead.org,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] lockdep: add lockdep_assert_not_held()
Date: Mon, 15 Feb 2021 11:44:02 +0100	[thread overview]
Message-ID: <20210215104402.GC4507@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <YCljfeNr4m5mZa4N@hirez.programming.kicks-ass.net>

On Sun, Feb 14, 2021 at 06:53:01PM +0100, Peter Zijlstra wrote:
> On Fri, Feb 12, 2021 at 04:28:42PM -0700, Shuah Khan wrote:
> 
> > +#define lockdep_assert_not_held(l)	do {			\
> > +		WARN_ON(debug_locks && lockdep_is_held(l));	\
> > +	} while (0)
> > +
> 
> This thing isn't as straight forward as you might think, but it'll
> mostly work.
> 
> Notably this thing will misfire when lockdep_off() is employed. It
> certainyl needs a comment to explain the subtleties.

I think something like so will work, but please double check.

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index b9e9adec73e8..c8b0d292bf8e 100644
--- a/include/linux/lockdep.h
+++ 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)
 
-#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.c
+++ 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() */
 
 	raw_local_irq_save(flags);
 	check_flags(flags);

WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org, ath10k@lists.infradead.org,
	mingo@redhat.com, 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 11:44:02 +0100	[thread overview]
Message-ID: <20210215104402.GC4507@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <YCljfeNr4m5mZa4N@hirez.programming.kicks-ass.net>

On Sun, Feb 14, 2021 at 06:53:01PM +0100, Peter Zijlstra wrote:
> On Fri, Feb 12, 2021 at 04:28:42PM -0700, Shuah Khan wrote:
> 
> > +#define lockdep_assert_not_held(l)	do {			\
> > +		WARN_ON(debug_locks && lockdep_is_held(l));	\
> > +	} while (0)
> > +
> 
> This thing isn't as straight forward as you might think, but it'll
> mostly work.
> 
> Notably this thing will misfire when lockdep_off() is employed. It
> certainyl needs a comment to explain the subtleties.

I think something like so will work, but please double check.

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index b9e9adec73e8..c8b0d292bf8e 100644
--- a/include/linux/lockdep.h
+++ 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)
 
-#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.c
+++ 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() */
 
 	raw_local_irq_save(flags);
 	check_flags(flags);

_______________________________________________
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ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

  reply	other threads:[~2021-02-15 10:45 UTC|newest]

Thread overview: 20+ 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 ` Shuah Khan
2021-02-12 23:28 ` [PATCH 1/2] lockdep: add lockdep_assert_not_held() Shuah Khan
2021-02-12 23:28   ` Shuah Khan
2021-02-14 17:53   ` Peter Zijlstra
2021-02-14 17:53     ` Peter Zijlstra
2021-02-15 10:44     ` Peter Zijlstra [this message]
2021-02-15 10:44       ` Peter Zijlstra
2021-02-15 13:12       ` Johannes Berg
2021-02-15 13:12         ` Johannes Berg
2021-02-15 16:04         ` Peter Zijlstra
2021-02-15 16:04           ` Peter Zijlstra
2021-02-15 16:10           ` Johannes Berg
2021-02-15 16:10             ` Johannes Berg
2021-02-22 20:51             ` Shuah Khan
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
2021-02-12 23:28   ` Shuah Khan
2021-02-14  6:08   ` Kalle Valo
2021-02-14  6:08     ` Kalle Valo

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