linux-kernel - Re: [PATCH] locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE

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Date:   Mon, 24 Jun 2019 18:07:40 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Will Deacon <will@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Bart Van Assche <bvanassche@....org>,
        Yuyang Du <duyuyang@...il.com>,
        Waiman Long <longman@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] locking/lockdep: Move mark_lock() inside
 CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING

On Mon, Jun 24, 2019 at 2:18 PM Will Deacon <will@...nel.org> wrote:
> On Mon, Jun 17, 2019 at 02:47:05PM +0200, Arnd Bergmann wrote:

> >
> > +unsigned long nr_stack_trace_entries;
> > +
> > +#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
>
> Is this necessary, given that CONFIG_PROVE_LOCKING selects TRACE_IRQFLAGS?
> I find that having both of the symbols makes this really hard to read.

Probably not. I have removed the CONFIG_TRACE_IRQFLAGS check from
all instances in this file now, and will give it some more testing.

It took me a few iterations to get to a version of this patch that had no
build failures, so I'm a bit careful. I had copied the #if check from what
protected some of the callers. If the change below works, I'll fold it
into my patch and send it again.

       Arnd

--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -448,7 +448,7 @@ static void print_lockdep_off(const char *bug_msg)

 unsigned long nr_stack_trace_entries;

-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+#ifdef CONFIG_PROVE_LOCKING
 /*
  * Stack-trace: tightly packed array of stack backtrace
  * addresses. Protected by the graph_lock.
@@ -491,7 +491,7 @@ unsigned int max_lockdep_depth;
 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
 #endif

-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+#ifdef CONFIG_PROVE_LOCKING
 /*
  * Locking printouts:
  */
@@ -2969,7 +2969,7 @@ static void check_chain_key(struct task_struct *curr)
 #endif
 }

-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+#ifdef CONFIG_PROVE_LOCKING
 static int mark_lock(struct task_struct *curr, struct held_lock *this,
                     enum lock_usage_bit new_bit);

@@ -3608,7 +3608,7 @@ static int mark_lock(struct task_struct *curr,
struct held_lock *this,
        return ret;
 }

-#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
+#else /* CONFIG_PROVE_LOCKING */

 static inline int
 mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
@@ -3627,7 +3627,7 @@ static inline int separate_irq_context(struct
task_struct *curr,
        return 0;
 }

-#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
+#endif /* CONFIG_PROVE_LOCKING */

 /*
  * Initialize a lock instance's lock-class mapping info:
@@ -4321,8 +4321,7 @@ static void __lock_unpin_lock(struct lockdep_map
*lock, struct pin_cookie cookie
  */
 static void check_flags(unsigned long flags)
 {
-#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
-    defined(CONFIG_TRACE_IRQFLAGS)
+#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
        if (!debug_locks)
                return;