Merge tag 'irq-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq updates from Thomas Gleixner:
 "The usual updates from the irq departement:

  Core changes:

   - Provide IRQF_NO_AUTOEN as a flag for request*_irq() so drivers can
     be cleaned up which either use a seperate mechanism to prevent
     auto-enable at request time or have a racy mechanism which disables
     the interrupt right after request.

   - Get rid of the last usage of irq_create_identity_mapping() and
     remove the interface.

   - An overhaul of tasklet_disable().

     Most usage sites of tasklet_disable() are in task context and
     usually in cleanup, teardown code pathes. tasklet_disable()
     spinwaits for a tasklet which is currently executed. That's not
     only a problem for PREEMPT_RT where this can lead to a live lock
     when the disabling task preempts the softirq thread. It's also
     problematic in context of virtualization when the vCPU which runs
     the tasklet is scheduled out and the disabling code has to spin
     wait until it's scheduled back in.

     There are a few code pathes which invoke tasklet_disable() from
     non-sleepable context. For these a new disable variant which still
     spinwaits is provided which allows to switch tasklet_disable() to a
     sleep wait mechanism. For the atomic use cases this does not solve
     the live lock issue on PREEMPT_RT. That is mitigated by blocking on
     the RT specific softirq lock.

   - The PREEMPT_RT specific implementation of softirq processing and
     local_bh_disable/enable().

     On RT enabled kernels soft interrupt processing happens always in
     task context and all interrupt handlers, which are not explicitly
     marked to be invoked in hard interrupt context are forced into task
     context as well. This allows to protect against softirq processing
     with a per CPU lock, which in turn allows to make BH disabled
     regions preemptible.

     Most of the softirq handling code is still shared. The RT/non-RT
     specific differences are addressed with a set of inline functions
     which provide the context specific functionality. The
     local_bh_disable() / local_bh_enable() mechanism are obviously
     seperate.

   - The usual set of small improvements and cleanups

  Driver changes:

   - New drivers for Nuvoton WPCM450 and DT 79rc3243x interrupt
     controllers

   - Extended functionality for MStar, STM32 and SC7280 irq chips

   - Enhanced robustness for ARM GICv3/4.1 drivers

   - The usual set of cleanups and improvements all over the place"

* tag 'irq-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
  irqchip/xilinx: Expose Kconfig option for Zynq/ZynqMP
  irqchip/gic-v3: Do not enable irqs when handling spurious interrups
  dt-bindings: interrupt-controller: Add IDT 79RC3243x Interrupt Controller
  irqchip: Add support for IDT 79rc3243x interrupt controller
  irqdomain: Drop references to recusive irqdomain setup
  irqdomain: Get rid of irq_create_strict_mappings()
  irqchip/jcore-aic: Kill use of irq_create_strict_mappings()
  ARM: PXA: Kill use of irq_create_strict_mappings()
  irqchip/gic-v4.1: Disable vSGI upon (GIC CPUIF < v4.1) detection
  irqchip/tb10x: Use 'fallthrough' to eliminate a warning
  genirq: Reduce irqdebug cacheline bouncing
  kernel: Initialize cpumask before parsing
  irqchip/wpcm450: Drop COMPILE_TEST
  irqchip/irq-mst: Support polarity configuration
  irqchip: Add driver for WPCM450 interrupt controller
  dt-bindings: interrupt-controller: Add nuvoton, wpcm450-aic
  dt-bindings: qcom,pdc: Add compatible for sc7280
  irqchip/stm32: Add usart instances exti direct event support
  irqchip/gic-v3: Fix OF_BAD_ADDR error handling
  irqchip/sifive-plic: Mark two global variables __ro_after_init
  ...

10 files changed, 46 insertions, 29 deletions

diff --git a/include/linux/bottom_half.h b/include/linux/bottom_half.h
index a19519f4241d..eed86eb0a1de 100644
--- a/include/linux/bottom_half.h
+++ b/include/linux/bottom_half.h
@@ -4,7 +4,7 @@
 
 #include <linux/preempt.h>
 
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_PREEMPT_RT) || defined(CONFIG_TRACE_IRQFLAGS)
 extern void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
 #else
 static __always_inline void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
@@ -32,4 +32,10 @@ static inline void local_bh_enable(void)
 	__local_bh_enable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
 }
 
+#ifdef CONFIG_PREEMPT_RT
+extern bool local_bh_blocked(void);
+#else
+static inline bool local_bh_blocked(void) { return false; }
+#endif
+
 #endif /* _LINUX_BH_H */
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 7c9d6a2d7e90..69bc86ea382c 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -6,6 +6,7 @@
 #include <linux/preempt.h>
 #include <linux/lockdep.h>
 #include <linux/ftrace_irq.h>
+#include <linux/sched.h>
 #include <linux/vtime.h>
 #include <asm/hardirq.h>
 
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 967e25767153..4777850a6dc7 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -61,6 +61,9 @@
  *                interrupt handler after suspending interrupts. For system
  *                wakeup devices users need to implement wakeup detection in
  *                their interrupt handlers.
+ * IRQF_NO_AUTOEN - Don't enable IRQ or NMI automatically when users request it.
+ *                Users will enable it explicitly by enable_irq() or enable_nmi()
+ *                later.
  */
 #define IRQF_SHARED		0x00000080
 #define IRQF_PROBE_SHARED	0x00000100
@@ -74,6 +77,7 @@
 #define IRQF_NO_THREAD		0x00010000
 #define IRQF_EARLY_RESUME	0x00020000
 #define IRQF_COND_SUSPEND	0x00040000
+#define IRQF_NO_AUTOEN		0x00080000
 
 #define IRQF_TIMER		(__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
 
@@ -654,26 +658,21 @@ enum
 	TASKLET_STATE_RUN	/* Tasklet is running (SMP only) */
 };
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
 static inline int tasklet_trylock(struct tasklet_struct *t)
 {
 	return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
 }
 
-static inline void tasklet_unlock(struct tasklet_struct *t)
-{
-	smp_mb__before_atomic();
-	clear_bit(TASKLET_STATE_RUN, &(t)->state);
-}
+void tasklet_unlock(struct tasklet_struct *t);
+void tasklet_unlock_wait(struct tasklet_struct *t);
+void tasklet_unlock_spin_wait(struct tasklet_struct *t);
 
-static inline void tasklet_unlock_wait(struct tasklet_struct *t)
-{
-	while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); }
-}
 #else
-#define tasklet_trylock(t) 1
-#define tasklet_unlock_wait(t) do { } while (0)
-#define tasklet_unlock(t) do { } while (0)
+static inline int tasklet_trylock(struct tasklet_struct *t) { return 1; }
+static inline void tasklet_unlock(struct tasklet_struct *t) { }
+static inline void tasklet_unlock_wait(struct tasklet_struct *t) { }
+static inline void tasklet_unlock_spin_wait(struct tasklet_struct *t) { }
 #endif
 
 extern void __tasklet_schedule(struct tasklet_struct *t);
@@ -698,6 +697,17 @@ static inline void tasklet_disable_nosync(struct tasklet_struct *t)
 	smp_mb__after_atomic();
 }
 
+/*
+ * Do not use in new code. Disabling tasklets from atomic contexts is
+ * error prone and should be avoided.
+ */
+static inline void tasklet_disable_in_atomic(struct tasklet_struct *t)
+{
+	tasklet_disable_nosync(t);
+	tasklet_unlock_spin_wait(t);
+	smp_mb();
+}
+
 static inline void tasklet_disable(struct tasklet_struct *t)
 {
 	tasklet_disable_nosync(t);
@@ -712,7 +722,6 @@ static inline void tasklet_enable(struct tasklet_struct *t)
 }
 
 extern void tasklet_kill(struct tasklet_struct *t);
-extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 extern void tasklet_init(struct tasklet_struct *t,
 			 void (*func)(unsigned long), unsigned long data);
 extern void tasklet_setup(struct tasklet_struct *t,
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 2efde6a79b7e..bee82809107c 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -116,7 +116,7 @@ enum {
  * IRQ_SET_MASK_NOCPY	- OK, chip did update irq_common_data.affinity
  * IRQ_SET_MASK_OK_DONE	- Same as IRQ_SET_MASK_OK for core. Special code to
  *			  support stacked irqchips, which indicates skipping
- *			  all descendent irqchips.
+ *			  all descendant irqchips.
  */
 enum {
 	IRQ_SET_MASK_OK = 0,
@@ -302,7 +302,7 @@ static inline bool irqd_is_level_type(struct irq_data *d)
 
 /*
  * Must only be called of irqchip.irq_set_affinity() or low level
- * hieararchy domain allocation functions.
+ * hierarchy domain allocation functions.
  */
 static inline void irqd_set_single_target(struct irq_data *d)
 {
diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h
index 943c3411ca10..2c63375bbd43 100644
--- a/include/linux/irqchip/arm-gic-v4.h
+++ b/include/linux/irqchip/arm-gic-v4.h
@@ -145,4 +145,6 @@ int its_init_v4(struct irq_domain *domain,
 		const struct irq_domain_ops *vpe_ops,
 		const struct irq_domain_ops *sgi_ops);
 
+bool gic_cpuif_has_vsgi(void);
+
 #endif
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 891b323266df..df4651250785 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -32,7 +32,7 @@ struct pt_regs;
  * @last_unhandled:	aging timer for unhandled count
  * @irqs_unhandled:	stats field for spurious unhandled interrupts
  * @threads_handled:	stats field for deferred spurious detection of threaded handlers
- * @threads_handled_last: comparator field for deferred spurious detection of theraded handlers
+ * @threads_handled_last: comparator field for deferred spurious detection of threaded handlers
  * @lock:		locking for SMP
  * @affinity_hint:	hint to user space for preferred irq affinity
  * @affinity_notify:	context for notification of affinity changes
diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 33cacc8af26d..7a1dd7b969b6 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -415,15 +415,6 @@ static inline unsigned int irq_linear_revmap(struct irq_domain *domain,
 extern unsigned int irq_find_mapping(struct irq_domain *host,
 				     irq_hw_number_t hwirq);
 extern unsigned int irq_create_direct_mapping(struct irq_domain *host);
-extern int irq_create_strict_mappings(struct irq_domain *domain,
-				      unsigned int irq_base,
-				      irq_hw_number_t hwirq_base, int count);
-
-static inline int irq_create_identity_mapping(struct irq_domain *host,
-					      irq_hw_number_t hwirq)
-{
-	return irq_create_strict_mappings(host, hwirq, hwirq, 1);
-}
 
 extern const struct irq_domain_ops irq_domain_simple_ops;
 
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 69cc8b64aa3a..9881eac0698f 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -79,7 +79,11 @@
 
 #define nmi_count()	(preempt_count() & NMI_MASK)
 #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
-#define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
+#ifdef CONFIG_PREEMPT_RT
+# define softirq_count()	(current->softirq_disable_cnt & SOFTIRQ_MASK)
+#else
+# define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
+#endif
 #define irq_count()	(nmi_count() | hardirq_count() | softirq_count())
 
 /*
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index bd04f722714f..6d855ef091ba 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -334,7 +334,8 @@ static inline void rcu_preempt_sleep_check(void) { }
 #define rcu_sleep_check()						\
 	do {								\
 		rcu_preempt_sleep_check();				\
-		RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map),	\
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))			\
+		    RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map),	\
 				 "Illegal context switch in RCU-bh read-side critical section"); \
 		RCU_LOCKDEP_WARN(lock_is_held(&rcu_sched_lock_map),	\
 				 "Illegal context switch in RCU-sched read-side critical section"); \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ef00bb22164c..743a613c9cf3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1044,6 +1044,9 @@ struct task_struct {
 	int				softirq_context;
 	int				irq_config;
 #endif
+#ifdef CONFIG_PREEMPT_RT
+	int				softirq_disable_cnt;
+#endif
 
 #ifdef CONFIG_LOCKDEP
 # define MAX_LOCK_DEPTH			48UL