lockdep: Add hrtimer context tracing bits

Set current->irq_config = 1 for hrtimers which are not marked to expire in
hard interrupt context during hrtimer_init(). These timers will expire in
softirq context on PREEMPT_RT.

Setting this allows lockdep to differentiate these timers. If a timer is
marked to expire in hard interrupt context then the timer callback is not
supposed to acquire a regular spinlock instead of a raw_spinlock in the
expiry callback.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.534508206@linutronix.de

diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
index fdaf286..9c17f9c 100644 (file)
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -56,6 +56,19 @@ do {                                         \
 do {                                           \
        current->softirq_context--;             \
 } while (0)
+
+# define lockdep_hrtimer_enter(__hrtimer)              \
+         do {                                          \
+                 if (!__hrtimer->is_hard)              \
+                       current->irq_config = 1;        \
+         } while (0)
+
+# define lockdep_hrtimer_exit(__hrtimer)               \
+         do {                                          \
+                 if (!__hrtimer->is_hard)              \
+                       current->irq_config = 0;        \
+         } while (0)
+
 #else
 # define trace_hardirqs_on()           do { } while (0)
 # define trace_hardirqs_off()          do { } while (0)
@@ -68,6 +81,8 @@ do {                                          \
 # define trace_hardirq_exit()          do { } while (0)
 # define lockdep_softirq_enter()       do { } while (0)
 # define lockdep_softirq_exit()                do { } while (0)
+# define lockdep_hrtimer_enter(__hrtimer)              do { } while (0)
+# define lockdep_hrtimer_exit(__hrtimer)               do { } while (0)
 #endif
 
 #if defined(CONFIG_IRQSOFF_TRACER) || \

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4d3b9ec..933914c 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -983,6 +983,7 @@ struct task_struct {
        unsigned int                    softirq_enable_event;
        int                             softirqs_enabled;
        int                             softirq_context;
+       int                             irq_config;
 #endif
 
 #ifdef CONFIG_LOCKDEP

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 6b9f9f3..0ebf980 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4025,7 +4025,7 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next)
                /*
                 * Check if force_irqthreads will run us threaded.
                 */
-               if (curr->hardirq_threaded)
+               if (curr->hardirq_threaded || curr->irq_config)
                        curr_inner = LD_WAIT_CONFIG;
                else
                        curr_inner = LD_WAIT_SPIN;

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 3a609e7..8cce725 100644 (file)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1404,7 +1404,7 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
        base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
        base += hrtimer_clockid_to_base(clock_id);
        timer->is_soft = softtimer;
-       timer->is_hard = !softtimer;
+       timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
        timer->base = &cpu_base->clock_base[base];
        timerqueue_init(&timer->node);
 }
@@ -1514,7 +1514,11 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
         */
        raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
        trace_hrtimer_expire_entry(timer, now);
+       lockdep_hrtimer_enter(timer);
+
        restart = fn(timer);
+
+       lockdep_hrtimer_exit(timer);
        trace_hrtimer_expire_exit(timer);
        raw_spin_lock_irq(&cpu_base->lock);