linux-kernel - [PATCH 01/14] lockdep: Add IRQs disabled/enabled assertion

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Date:   Fri, 20 Oct 2017 02:55:58 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Tejun Heo <tj@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "David S . Miller" <davem@...emloft.net>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 01/14] lockdep: Add IRQs disabled/enabled assertion

Checking whether IRQs are enabled or disabled is a very common sanity
check, however not free of overhead especially on fastpath where such
assertion is very common.

Lockdep is a good host for such concurrency correctness check and it
even already tracks down IRQs disablement state. Just reuse its
machinery. This will allow us to get rid of the flags pop and check
overhead from fast path when kernel is built for production.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 include/linux/lockdep.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index bfa8e0b..fbe0127 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -719,9 +719,22 @@ do {									\
 	lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_);	\
 	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
 } while (0)
+
+#define lockdep_assert_irqs_enabled()	({				\
+		!WARN_ONCE(debug_locks && !current->hardirqs_enabled,	\
+			   "IRQs not enabled as expected\n");		\
+	})
+
+#define lockdep_assert_irqs_disabled()	({				\
+		!WARN_ONCE(debug_locks && current->hardirqs_enabled,	\
+			   "IRQs not disabled as expected\n");		\
+	})
+
 #else
 # define might_lock(lock) do { } while (0)
 # define might_lock_read(lock) do { } while (0)
+static inline int lockdep_assert_irqs_enabled(void) { return 1; }
+static inline int lockdep_assert_irqs_disabled(void) { return 1; }
 #endif
 
 #ifdef CONFIG_LOCKDEP
-- 
2.7.4