linux-kernel - Re: [PATCH v2 01/34] compiler_types: Move lock checking attributes to compiler-capability-analysis.h

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Message-ID: <Z8gVyLIU71Fg1QWK@elver.google.com>
Date: Wed, 5 Mar 2025 10:13:44 +0100
From: Marco Elver <elver@...gle.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: "David S. Miller" <davem@...emloft.net>,
	Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Alexander Potapenko <glider@...gle.com>,
	Arnd Bergmann <arnd@...db.de>, Bart Van Assche <bvanassche@....org>,
	Bill Wendling <morbo@...gle.com>, Boqun Feng <boqun.feng@...il.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Frederic Weisbecker <frederic@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Ingo Molnar <mingo@...nel.org>, Jann Horn <jannh@...gle.com>,
	Jiri Slaby <jirislaby@...nel.org>,
	Joel Fernandes <joel@...lfernandes.org>,
	Jonathan Corbet <corbet@....net>,
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	Kentaro Takeda <takedakn@...data.co.jp>,
	Mark Rutland <mark.rutland@....com>,
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	Miguel Ojeda <ojeda@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Thomas Gleixner <tglx@...utronix.de>,
	Uladzislau Rezki <urezki@...il.com>,
	Waiman Long <longman@...hat.com>, Will Deacon <will@...nel.org>,
	kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev, rcu@...r.kernel.org,
	linux-crypto@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v2 01/34] compiler_types: Move lock checking attributes
 to compiler-capability-analysis.h

On Wed, Mar 05, 2025 at 11:36AM +0300, Dan Carpenter wrote:
> On Tue, Mar 04, 2025 at 10:21:00AM +0100, Marco Elver wrote:
> > +#ifndef _LINUX_COMPILER_CAPABILITY_ANALYSIS_H
> > +#define _LINUX_COMPILER_CAPABILITY_ANALYSIS_H
> > +
> > +#ifdef __CHECKER__
> > +
> > +/* Sparse context/lock checking support. */
> > +# define __must_hold(x)		__attribute__((context(x,1,1)))
> > +# define __acquires(x)		__attribute__((context(x,0,1)))
> > +# define __cond_acquires(x)	__attribute__((context(x,0,-1)))
> > +# define __releases(x)		__attribute__((context(x,1,0)))
> > +# define __acquire(x)		__context__(x,1)
> > +# define __release(x)		__context__(x,-1)
> > +# define __cond_lock(x, c)	((c) ? ({ __acquire(x); 1; }) : 0)
> > +
> 
> The other thing you might want to annotate is ww_mutex_destroy().

We can add an annotation to check the lock is not held:


diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 63978cb36a98..549d75aee76a 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -372,6 +372,7 @@ extern int __must_check ww_mutex_trylock(struct ww_mutex *lock,
  * this function is called.
  */
 static inline void ww_mutex_destroy(struct ww_mutex *lock)
+	__must_not_hold(lock)
 {
 #ifndef CONFIG_PREEMPT_RT
 	mutex_destroy(&lock->base);
diff --git a/lib/test_capability-analysis.c b/lib/test_capability-analysis.c
index 13e7732c38a2..1a466b362373 100644
--- a/lib/test_capability-analysis.c
+++ b/lib/test_capability-analysis.c
@@ -516,6 +516,8 @@ static void __used test_ww_mutex_lock_noctx(struct test_ww_mutex_data *d)
 	ww_mutex_lock_slow(&d->mtx, NULL);
 	d->counter++;
 	ww_mutex_unlock(&d->mtx);
+
+	ww_mutex_destroy(&d->mtx);
 }
 
 static void __used test_ww_mutex_lock_ctx(struct test_ww_mutex_data *d)
@@ -545,4 +547,6 @@ static void __used test_ww_mutex_lock_ctx(struct test_ww_mutex_data *d)
 
 	ww_acquire_done(&ctx);
 	ww_acquire_fini(&ctx);
+
+	ww_mutex_destroy(&d->mtx);
 }


Probably a fixup for the ww_mutex patch:
https://lore.kernel.org/all/20250304092417.2873893-21-elver@google.com/
Or extra patch depending on when/if Peter decides to take the series.

> I'm happy about the new __guarded_by annotation.

Thanks!

-- Marco