lockdep: Change hardirq{s_enabled,_context} to per-cpu variables

Currently all IRQ-tracking state is in task_struct, this means that
task_struct needs to be defined before we use it.

Especially for lockdep_assert_irq*() this can lead to header-hell.

Move the hardirq state into per-cpu variables to avoid the task_struct
dependency.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200623083721.512673481@infradead.org

3 files changed, 22 insertions, 18 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index efc5493203ae..70d9d0a4de2a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1954,8 +1954,8 @@ static __latent_entropy struct task_struct *copy_process(
 
 	rt_mutex_init_task(p);
 
+	lockdep_assert_irqs_enabled();
 #ifdef CONFIG_PROVE_LOCKING
-	DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
 	DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
 #endif
 	retval = -EAGAIN;
@@ -2036,7 +2036,6 @@ static __latent_entropy struct task_struct *copy_process(
 #endif
 #ifdef CONFIG_TRACE_IRQFLAGS
 	p->irq_events = 0;
-	p->hardirqs_enabled = 0;
 	p->hardirq_enable_ip = 0;
 	p->hardirq_enable_event = 0;
 	p->hardirq_disable_ip = _THIS_IP_;
@@ -2046,7 +2045,6 @@ static __latent_entropy struct task_struct *copy_process(
 	p->softirq_enable_event = 0;
 	p->softirq_disable_ip = 0;
 	p->softirq_disable_event = 0;
-	p->hardirq_context = 0;
 	p->softirq_context = 0;
 #endif
 
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index d595623c4b34..ab4ffbe0e9e9 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2062,9 +2062,9 @@ print_bad_irq_dependency(struct task_struct *curr,
 	pr_warn("-----------------------------------------------------\n");
 	pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
 		curr->comm, task_pid_nr(curr),
-		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
+		lockdep_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
 		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
-		curr->hardirqs_enabled,
+		lockdep_hardirqs_enabled(curr),
 		curr->softirqs_enabled);
 	print_lock(next);
 
@@ -3658,7 +3658,7 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
 	if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
 		return;
 
-	if (unlikely(current->hardirqs_enabled)) {
+	if (unlikely(lockdep_hardirqs_enabled(current))) {
 		/*
 		 * Neither irq nor preemption are disabled here
 		 * so this is racy by nature but losing one hit
@@ -3686,7 +3686,7 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
 	 * Can't allow enabling interrupts while in an interrupt handler,
 	 * that's general bad form and such. Recursion, limited stack etc..
 	 */
-	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+	if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context(current)))
 		return;
 
 	current->hardirq_chain_key = current->curr_chain_key;
@@ -3724,7 +3724,7 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
 	if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
 		return;
 
-	if (curr->hardirqs_enabled) {
+	if (lockdep_hardirqs_enabled(curr)) {
 		/*
 		 * Neither irq nor preemption are disabled here
 		 * so this is racy by nature but losing one hit
@@ -3751,7 +3751,7 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
 
 skip_checks:
 	/* we'll do an OFF -> ON transition: */
-	curr->hardirqs_enabled = 1;
+	this_cpu_write(hardirqs_enabled, 1);
 	curr->hardirq_enable_ip = ip;
 	curr->hardirq_enable_event = ++curr->irq_events;
 	debug_atomic_inc(hardirqs_on_events);
@@ -3783,11 +3783,11 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
 	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
 		return;
 
-	if (curr->hardirqs_enabled) {
+	if (lockdep_hardirqs_enabled(curr)) {
 		/*
 		 * We have done an ON -> OFF transition:
 		 */
-		curr->hardirqs_enabled = 0;
+		this_cpu_write(hardirqs_enabled, 0);
 		curr->hardirq_disable_ip = ip;
 		curr->hardirq_disable_event = ++curr->irq_events;
 		debug_atomic_inc(hardirqs_off_events);
@@ -3832,7 +3832,7 @@ void lockdep_softirqs_on(unsigned long ip)
 	 * usage bit for all held locks, if hardirqs are
 	 * enabled too:
 	 */
-	if (curr->hardirqs_enabled)
+	if (lockdep_hardirqs_enabled(curr))
 		mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
 	lockdep_recursion_finish();
 }
@@ -3881,7 +3881,7 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
 	 */
 	if (!hlock->trylock) {
 		if (hlock->read) {
-			if (curr->hardirq_context)
+			if (lockdep_hardirq_context(curr))
 				if (!mark_lock(curr, hlock,
 						LOCK_USED_IN_HARDIRQ_READ))
 					return 0;
@@ -3890,7 +3890,7 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
 						LOCK_USED_IN_SOFTIRQ_READ))
 					return 0;
 		} else {
-			if (curr->hardirq_context)
+			if (lockdep_hardirq_context(curr))
 				if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
 					return 0;
 			if (curr->softirq_context)
@@ -3928,7 +3928,7 @@ lock_used:
 
 static inline unsigned int task_irq_context(struct task_struct *task)
 {
-	return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context +
+	return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context(task) +
 	       LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
 }
 
@@ -4021,7 +4021,7 @@ static inline short task_wait_context(struct task_struct *curr)
 	 * Set appropriate wait type for the context; for IRQs we have to take
 	 * into account force_irqthread as that is implied by PREEMPT_RT.
 	 */
-	if (curr->hardirq_context) {
+	if (lockdep_hardirq_context(curr)) {
 		/*
 		 * Check if force_irqthreads will run us threaded.
 		 */
@@ -4864,11 +4864,11 @@ static void check_flags(unsigned long flags)
 		return;
 
 	if (irqs_disabled_flags(flags)) {
-		if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
+		if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled(current))) {
 			printk("possible reason: unannotated irqs-off.\n");
 		}
 	} else {
-		if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
+		if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled(current))) {
 			printk("possible reason: unannotated irqs-on.\n");
 		}
 	}
diff --git a/kernel/softirq.c b/kernel/softirq.c
index c4201b7f42b1..342c53feaa7a 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -107,6 +107,12 @@ static bool ksoftirqd_running(unsigned long pending)
  * where hardirqs are disabled legitimately:
  */
 #ifdef CONFIG_TRACE_IRQFLAGS
+
+DEFINE_PER_CPU(int, hardirqs_enabled);
+DEFINE_PER_CPU(int, hardirq_context);
+EXPORT_PER_CPU_SYMBOL_GPL(hardirqs_enabled);
+EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context);
+
 void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
 {
 	unsigned long flags;