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From:   john.hubbard@gmail.com
To:     LKML <linux-kernel@vger.kernel.org>
Cc:     John Hubbard <jhubbard@nvidia.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>
Subject: [PATCH 1/1] lockdep: fix warning: print_lock_trace defined but not used
Date:   Tue, 21 May 2019 00:08:08 -0700
Message-Id: <20190521070808.3536-2-jhubbard@nvidia.com>
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References: <20190521070808.3536-1-jhubbard@nvidia.com>
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From: John Hubbard <jhubbard@nvidia.com>

Commit 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside
CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING") moved the only usage of
print_lock_trace() that was originally outside of the CONFIG_PROVE_LOCKING
case. It moved that usage into a different case: CONFIG_PROVE_LOCKING &&
CONFIG_TRACE_IRQFLAGS. That leaves things not symmetrical, and as a result,
the following warning fires on my build, when I have

!CONFIG_TRACE_IRQFLAGS && !CONFIG_PROVE_LOCKING

set:

kernel/locking/lockdep.c:2821:13: warning: ‘print_lock_trace’ defined
    but not used [-Wunused-function]

Fix this by only defining print_lock_trace() in cases in which is it
called.

Fixes: 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 kernel/locking/lockdep.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index d06190fa5082..3065dc36c27a 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2817,11 +2817,14 @@ static inline int validate_chain(struct task_struct *curr,
 	return 1;
 }
 
+#if defined(CONFIG_TRACE_IRQFLAGS)
 static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
 {
 }
 #endif
 
+#endif
+
 /*
  * We are building curr_chain_key incrementally, so double-check
  * it from scratch, to make sure that it's done correctly:
-- 
2.21.0