linux-kernel - [PATCH 13/32] softirq: Pass softirq vector number to lockdep on vector execution

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Date:   Tue, 12 Feb 2019 18:14:04 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Mauro Carvalho Chehab <mchehab@...pensource.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "David S . Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Pavan Kondeti <pkondeti@...eaurora.org>,
        Ingo Molnar <mingo@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>
Subject: [PATCH 13/32] softirq: Pass softirq vector number to lockdep on vector execution

Pass the softirq vector number to lockdep on callback execution so that
we know which one is involved while holding a lock. We will then be able
to pick up the proper LOCK_USED_IN_*_SOFTIRQ index to perform the
finegrained verifications.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Mauro Carvalho Chehab <mchehab@...pensource.com>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Pavan Kondeti <pkondeti@...eaurora.org>
Cc: Paul E . McKenney <paulmck@...ux.vnet.ibm.com>
Cc: David S . Miller <davem@...emloft.net>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
---
 include/linux/irqflags.h | 12 ++++++------
 kernel/softirq.c         |  8 ++++----
 lib/locking-selftest.c   |  4 ++--
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
index 21619c92c377..623030a74866 100644
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -43,13 +43,13 @@ do {						\
 do {						\
 	current->hardirq_context--;		\
 } while (0)
-# define lockdep_softirq_enter()		\
+# define lockdep_softirq_enter(__VEC)		\
 do {						\
-	current->softirq_context++;		\
+	current->softirq_context |= BIT(__VEC);	\
 } while (0)
-# define lockdep_softirq_exit()			\
+# define lockdep_softirq_exit(__VEC)		\
 do {						\
-	current->softirq_context--;		\
+	current->softirq_context &= ~BIT(__VEC);\
 } while (0)
 #else
 # define trace_hardirqs_on()		do { } while (0)
@@ -60,8 +60,8 @@ do {						\
 # define trace_softirqs_enabled(p)	0
 # define trace_hardirq_enter()		do { } while (0)
 # define trace_hardirq_exit()		do { } while (0)
-# define lockdep_softirq_enter()	do { } while (0)
-# define lockdep_softirq_exit()		do { } while (0)
+# define lockdep_softirq_enter(vec)	do { } while (0)
+# define lockdep_softirq_exit(vec)	do { } while (0)
 #endif
 
 #if defined(CONFIG_IRQSOFF_TRACER) || \
diff --git a/kernel/softirq.c b/kernel/softirq.c
index d28813306b2c..2dcaef813acb 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -229,18 +229,15 @@ static inline bool lockdep_softirq_start(void)
 		trace_hardirq_exit();
 	}
 
-	lockdep_softirq_enter();
-
 	return in_hardirq;
 }
 
 static inline void lockdep_softirq_end(bool in_hardirq)
 {
-	lockdep_softirq_exit();
-
 	if (in_hardirq)
 		trace_hardirq_enter();
 }
+
 #else
 static inline bool lockdep_softirq_start(void) { return false; }
 static inline void lockdep_softirq_end(bool in_hardirq) { }
@@ -288,9 +285,12 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 
 		kstat_incr_softirqs_this_cpu(vec_nr);
 
+		lockdep_softirq_enter(vec_nr);
 		trace_softirq_entry(vec_nr);
 		h->action(h);
 		trace_softirq_exit(vec_nr);
+		lockdep_softirq_exit(vec_nr);
+
 		if (unlikely(prev_count != preempt_count())) {
 			pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
 			       vec_nr, softirq_to_name[vec_nr], h->action,
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 1e1bbf171eca..2bd782d7f2e5 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -197,11 +197,11 @@ static void init_shared_classes(void)
 #define SOFTIRQ_ENTER()				\
 		local_bh_disable();		\
 		local_irq_disable();		\
-		lockdep_softirq_enter();	\
+		lockdep_softirq_enter(0);	\
 		WARN_ON(!in_softirq());
 
 #define SOFTIRQ_EXIT()				\
-		lockdep_softirq_exit();		\
+		lockdep_softirq_exit(0);	\
 		local_irq_enable();		\
 		local_bh_enable();
 
-- 
2.17.1