Merge branch 'irq/core'

45 files changed, 428 insertions, 166 deletions

diff --git a/drivers/atm/eni.c b/drivers/atm/eni.c
index b574cce98dc3..422753d52244 100644
--- a/drivers/atm/eni.c
+++ b/drivers/atm/eni.c
@@ -2054,7 +2054,7 @@ static int eni_send(struct atm_vcc *vcc,struct sk_buff *skb)
 	}
 	submitted++;
 	ATM_SKB(skb)->vcc = vcc;
-	tasklet_disable(&ENI_DEV(vcc->dev)->task);
+	tasklet_disable_in_atomic(&ENI_DEV(vcc->dev)->task);
 	res = do_tx(skb);
 	tasklet_enable(&ENI_DEV(vcc->dev)->task);
 	if (res == enq_ok) return 0;
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 9811c40956e5..17c9d825188b 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2545,7 +2545,7 @@ static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
 	struct driver_data *driver_data = packet->driver_data;
 	int ret = -ENOENT;
 
-	tasklet_disable(&ctx->tasklet);
+	tasklet_disable_in_atomic(&ctx->tasklet);
 
 	if (packet->ack != 0)
 		goto out;
@@ -3465,7 +3465,7 @@ static int ohci_flush_iso_completions(struct fw_iso_context *base)
 	struct iso_context *ctx = container_of(base, struct iso_context, base);
 	int ret = 0;
 
-	tasklet_disable(&ctx->context.tasklet);
+	tasklet_disable_in_atomic(&ctx->context.tasklet);
 
 	if (!test_and_set_bit_lock(0, &ctx->flushing_completions)) {
 		context_tasklet((unsigned long)&ctx->context);
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index e622aee6e4be..440c35f1abc9 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -105,7 +105,7 @@ static inline bool tasklet_is_locked(const struct tasklet_struct *t)
 static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
 {
 	if (!atomic_fetch_inc(&t->count))
-		tasklet_unlock_wait(t);
+		tasklet_unlock_spin_wait(t);
 }
 
 static inline bool __tasklet_is_enabled(const struct tasklet_struct *t)
diff --git a/drivers/irqchip/irq-aspeed-vic.c b/drivers/irqchip/irq-aspeed-vic.c
index 6567ed782f82..58717cd44f99 100644
--- a/drivers/irqchip/irq-aspeed-vic.c
+++ b/drivers/irqchip/irq-aspeed-vic.c
@@ -71,7 +71,7 @@ static void vic_init_hw(struct aspeed_vic *vic)
 	writel(0, vic->base + AVIC_INT_SELECT);
 	writel(0, vic->base + AVIC_INT_SELECT + 4);
 
-	/* Some interrupts have a programable high/low level trigger
+	/* Some interrupts have a programmable high/low level trigger
 	 * (4 GPIO direct inputs), for now we assume this was configured
 	 * by firmware. We read which ones are edge now.
 	 */
@@ -203,7 +203,7 @@ static int __init avic_of_init(struct device_node *node,
 	}
 	vic->base = regs;
 
-	/* Initialize soures, all masked */
+	/* Initialize sources, all masked */
 	vic_init_hw(vic);
 
 	/* Ready to receive interrupts */
diff --git a/drivers/irqchip/irq-bcm7120-l2.c b/drivers/irqchip/irq-bcm7120-l2.c
index c7c9e976acbb..ad59656ccc28 100644
--- a/drivers/irqchip/irq-bcm7120-l2.c
+++ b/drivers/irqchip/irq-bcm7120-l2.c
@@ -309,7 +309,7 @@ static int __init bcm7120_l2_intc_probe(struct device_node *dn,
 
 		if (data->can_wake) {
 			/* This IRQ chip can wake the system, set all
-			 * relevant child interupts in wake_enabled mask
+			 * relevant child interrupts in wake_enabled mask
 			 */
 			gc->wake_enabled = 0xffffffff;
 			gc->wake_enabled &= ~gc->unused;
diff --git a/drivers/irqchip/irq-csky-apb-intc.c b/drivers/irqchip/irq-csky-apb-intc.c
index 5a2ec43b7ddd..ab91afa86755 100644
--- a/drivers/irqchip/irq-csky-apb-intc.c
+++ b/drivers/irqchip/irq-csky-apb-intc.c
@@ -176,7 +176,7 @@ gx_intc_init(struct device_node *node, struct device_node *parent)
 	writel(0x0, reg_base + GX_INTC_NEN63_32);
 
 	/*
-	 * Initial mask reg with all unmasked, because we only use enalbe reg
+	 * Initial mask reg with all unmasked, because we only use enable reg
 	 */
 	writel(0x0, reg_base + GX_INTC_NMASK31_00);
 	writel(0x0, reg_base + GX_INTC_NMASK63_32);
diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index fbec07d634ad..4116b48e60af 100644
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -371,7 +371,7 @@ static int __init gicv2m_init_one(struct fwnode_handle *fwnode,
 	 * the MSI data is the absolute value within the range from
 	 * spi_start to (spi_start + num_spis).
 	 *
-	 * Broadom NS2 GICv2m implementation has an erratum where the MSI data
+	 * Broadcom NS2 GICv2m implementation has an erratum where the MSI data
 	 * is 'spi_number - 32'
 	 *
 	 * Reading that register fails on the Graviton implementation
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index ed46e6057e33..c3485b230d70 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1492,7 +1492,7 @@ static void its_vlpi_set_doorbell(struct irq_data *d, bool enable)
 	 *
 	 * Ideally, we'd issue a VMAPTI to set the doorbell to its LPI
 	 * value or to 1023, depending on the enable bit. But that
-	 * would be issueing a mapping for an /existing/ DevID+EventID
+	 * would be issuing a mapping for an /existing/ DevID+EventID
 	 * pair, which is UNPREDICTABLE. Instead, let's issue a VMOVI
 	 * to the /same/ vPE, using this opportunity to adjust the
 	 * doorbell. Mouahahahaha. We loves it, Precious.
@@ -3122,7 +3122,7 @@ static void its_cpu_init_lpis(void)
 
 		/*
 		 * It's possible for CPU to receive VLPIs before it is
-		 * sheduled as a vPE, especially for the first CPU, and the
+		 * scheduled as a vPE, especially for the first CPU, and the
 		 * VLPI with INTID larger than 2^(IDbits+1) will be considered
 		 * as out of range and dropped by GIC.
 		 * So we initialize IDbits to known value to avoid VLPI drop.
@@ -3616,7 +3616,7 @@ static void its_irq_domain_free(struct irq_domain *domain, unsigned int virq,
 
 	/*
 	 * If all interrupts have been freed, start mopping the
-	 * floor. This is conditionned on the device not being shared.
+	 * floor. This is conditioned on the device not being shared.
 	 */
 	if (!its_dev->shared &&
 	    bitmap_empty(its_dev->event_map.lpi_map,
@@ -4194,7 +4194,7 @@ static int its_sgi_set_affinity(struct irq_data *d,
 {
 	/*
 	 * There is no notion of affinity for virtual SGIs, at least
-	 * not on the host (since they can only be targetting a vPE).
+	 * not on the host (since they can only be targeting a vPE).
 	 * Tell the kernel we've done whatever it asked for.
 	 */
 	irq_data_update_effective_affinity(d, mask_val);
@@ -4239,7 +4239,7 @@ static int its_sgi_get_irqchip_state(struct irq_data *d,
 	/*
 	 * Locking galore! We can race against two different events:
 	 *
-	 * - Concurent vPE affinity change: we must make sure it cannot
+	 * - Concurrent vPE affinity change: we must make sure it cannot
 	 *   happen, or we'll talk to the wrong redistributor. This is
 	 *   identical to what happens with vLPIs.
 	 *
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index eb0ee356a629..94b89258d045 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1379,7 +1379,7 @@ static int gic_irq_domain_translate(struct irq_domain *d,
 
 		/*
 		 * Make it clear that broken DTs are... broken.
-		 * Partitionned PPIs are an unfortunate exception.
+		 * Partitioned PPIs are an unfortunate exception.
 		 */
 		WARN_ON(*type == IRQ_TYPE_NONE &&
 			fwspec->param[0] != GIC_IRQ_TYPE_PARTITION);
diff --git a/drivers/irqchip/irq-loongson-pch-pic.c b/drivers/irqchip/irq-loongson-pch-pic.c
index 9bf6b9a5f734..f790ca6d78aa 100644
--- a/drivers/irqchip/irq-loongson-pch-pic.c
+++ b/drivers/irqchip/irq-loongson-pch-pic.c
@@ -163,7 +163,7 @@ static void pch_pic_reset(struct pch_pic *priv)
 	int i;
 
 	for (i = 0; i < PIC_COUNT; i++) {
-		/* Write vectore ID */
+		/* Write vectored ID */
 		writeb(priv->ht_vec_base + i, priv->base + PCH_INT_HTVEC(i));
 		/* Hardcode route to HT0 Lo */
 		writeb(1, priv->base + PCH_INT_ROUTE(i));
diff --git a/drivers/irqchip/irq-meson-gpio.c b/drivers/irqchip/irq-meson-gpio.c
index bc7aebcc96e9..e50676ce2ec8 100644
--- a/drivers/irqchip/irq-meson-gpio.c
+++ b/drivers/irqchip/irq-meson-gpio.c
@@ -227,7 +227,7 @@ meson_gpio_irq_request_channel(struct meson_gpio_irq_controller *ctl,
 
 	/*
 	 * Get the hwirq number assigned to this channel through
-	 * a pointer the channel_irq table. The added benifit of this
+	 * a pointer the channel_irq table. The added benefit of this
 	 * method is that we can also retrieve the channel index with
 	 * it, using the table base.
 	 */
diff --git a/drivers/irqchip/irq-mtk-cirq.c b/drivers/irqchip/irq-mtk-cirq.c
index 69ba8ce3c178..9bca0918078e 100644
--- a/drivers/irqchip/irq-mtk-cirq.c
+++ b/drivers/irqchip/irq-mtk-cirq.c
@@ -217,7 +217,7 @@ static void mtk_cirq_resume(void)
 {
 	u32 value;
 
-	/* flush recored interrupts, will send signals to parent controller */
+	/* flush recorded interrupts, will send signals to parent controller */
 	value = readl_relaxed(cirq_data->base + CIRQ_CONTROL);
 	writel_relaxed(value | CIRQ_FLUSH, cirq_data->base + CIRQ_CONTROL);
 
diff --git a/drivers/irqchip/irq-mxs.c b/drivers/irqchip/irq-mxs.c
index a671938fd97f..d1f5740cd575 100644
--- a/drivers/irqchip/irq-mxs.c
+++ b/drivers/irqchip/irq-mxs.c
@@ -58,7 +58,7 @@ struct icoll_priv {
 static struct icoll_priv icoll_priv;
 static struct irq_domain *icoll_domain;
 
-/* calculate bit offset depending on number of intterupt per register */
+/* calculate bit offset depending on number of interrupt per register */
 static u32 icoll_intr_bitshift(struct irq_data *d, u32 bit)
 {
 	/*
@@ -68,7 +68,7 @@ static u32 icoll_intr_bitshift(struct irq_data *d, u32 bit)
 	return bit << ((d->hwirq & 3) << 3);
 }
 
-/* calculate mem offset depending on number of intterupt per register */
+/* calculate mem offset depending on number of interrupt per register */
 static void __iomem *icoll_intr_reg(struct irq_data *d)
 {
 	/* offset = hwirq / intr_per_reg * 0x10 */
diff --git a/drivers/irqchip/irq-sun4i.c b/drivers/irqchip/irq-sun4i.c
index fb78d6623556..9ea94456b178 100644
--- a/drivers/irqchip/irq-sun4i.c
+++ b/drivers/irqchip/irq-sun4i.c
@@ -189,7 +189,7 @@ static void __exception_irq_entry sun4i_handle_irq(struct pt_regs *regs)
 	 * 3) spurious irq
 	 * So if we immediately get a reading of 0, check the irq-pending reg
 	 * to differentiate between 2 and 3. We only do this once to avoid
-	 * the extra check in the common case of 1 hapening after having
+	 * the extra check in the common case of 1 happening after having
 	 * read the vector-reg once.
 	 */
 	hwirq = readl(irq_ic_data->irq_base + SUN4I_IRQ_VECTOR_REG) >> 2;
diff --git a/drivers/irqchip/irq-ti-sci-inta.c b/drivers/irqchip/irq-ti-sci-inta.c
index 532d0ae172d9..ca1f593f4d13 100644
--- a/drivers/irqchip/irq-ti-sci-inta.c
+++ b/drivers/irqchip/irq-ti-sci-inta.c
@@ -78,7 +78,7 @@ struct ti_sci_inta_vint_desc {
  * struct ti_sci_inta_irq_domain - Structure representing a TISCI based
  *				   Interrupt Aggregator IRQ domain.
  * @sci:		Pointer to TISCI handle
- * @vint:		TISCI resource pointer representing IA inerrupts.
+ * @vint:		TISCI resource pointer representing IA interrupts.
  * @global_event:	TISCI resource pointer representing global events.
  * @vint_list:		List of the vints active in the system
  * @vint_mutex:		Mutex to protect vint_list
diff --git a/drivers/irqchip/irq-vic.c b/drivers/irqchip/irq-vic.c
index e46036374227..62f3d29f9042 100644
--- a/drivers/irqchip/irq-vic.c
+++ b/drivers/irqchip/irq-vic.c
@@ -163,7 +163,7 @@ static struct syscore_ops vic_syscore_ops = {
 };
 
 /**
- * vic_pm_init - initicall to register VIC pm
+ * vic_pm_init - initcall to register VIC pm
  *
  * This is called via late_initcall() to register
  * the resources for the VICs due to the early
@@ -397,7 +397,7 @@ static void __init vic_clear_interrupts(void __iomem *base)
 /*
  * The PL190 cell from ARM has been modified by ST to handle 64 interrupts.
  * The original cell has 32 interrupts, while the modified one has 64,
- * replocating two blocks 0x00..0x1f in 0x20..0x3f. In that case
+ * replicating two blocks 0x00..0x1f in 0x20..0x3f. In that case
  * the probe function is called twice, with base set to offset 000
  *  and 020 within the page. We call this "second block".
  */
diff --git a/drivers/irqchip/irq-xilinx-intc.c b/drivers/irqchip/irq-xilinx-intc.c
index 1d3d273309bd..8cd1bfc73057 100644
--- a/drivers/irqchip/irq-xilinx-intc.c
+++ b/drivers/irqchip/irq-xilinx-intc.c
@@ -210,7 +210,7 @@ static int __init xilinx_intc_of_init(struct device_node *intc,
 
 	/*
 	 * Disable all external interrupts until they are
-	 * explicity requested.
+	 * explicitly requested.
 	 */
 	xintc_write(irqc, IER, 0);
 
diff --git a/drivers/net/ethernet/dlink/sundance.c b/drivers/net/ethernet/dlink/sundance.c
index e3a8858915b3..df0eab479d51 100644
--- a/drivers/net/ethernet/dlink/sundance.c
+++ b/drivers/net/ethernet/dlink/sundance.c
@@ -963,7 +963,7 @@ static void tx_timeout(struct net_device *dev, unsigned int txqueue)
 	unsigned long flag;
 
 	netif_stop_queue(dev);
-	tasklet_disable(&np->tx_tasklet);
+	tasklet_disable_in_atomic(&np->tx_tasklet);
 	iowrite16(0, ioaddr + IntrEnable);
 	printk(KERN_WARNING "%s: Transmit timed out, TxStatus %2.2x "
 		   "TxFrameId %2.2x,"
diff --git a/drivers/net/ethernet/jme.c b/drivers/net/ethernet/jme.c
index e9efe074edc1..f1b9284e0bea 100644
--- a/drivers/net/ethernet/jme.c
+++ b/drivers/net/ethernet/jme.c
@@ -1265,9 +1265,9 @@ jme_stop_shutdown_timer(struct jme_adapter *jme)
 	jwrite32f(jme, JME_APMC, apmc);
 }
 
-static void jme_link_change_tasklet(struct tasklet_struct *t)
+static void jme_link_change_work(struct work_struct *work)
 {
-	struct jme_adapter *jme = from_tasklet(jme, t, linkch_task);
+	struct jme_adapter *jme = container_of(work, struct jme_adapter, linkch_task);
 	struct net_device *netdev = jme->dev;
 	int rc;
 
@@ -1510,7 +1510,7 @@ jme_intr_msi(struct jme_adapter *jme, u32 intrstat)
 		 * all other events are ignored
 		 */
 		jwrite32(jme, JME_IEVE, intrstat);
-		tasklet_schedule(&jme->linkch_task);
+		schedule_work(&jme->linkch_task);
 		goto out_reenable;
 	}
 
@@ -1832,7 +1832,6 @@ jme_open(struct net_device *netdev)
 	jme_clear_pm_disable_wol(jme);
 	JME_NAPI_ENABLE(jme);
 
-	tasklet_setup(&jme->linkch_task, jme_link_change_tasklet);
 	tasklet_setup(&jme->txclean_task, jme_tx_clean_tasklet);
 	tasklet_setup(&jme->rxclean_task, jme_rx_clean_tasklet);
 	tasklet_setup(&jme->rxempty_task, jme_rx_empty_tasklet);
@@ -1920,7 +1919,7 @@ jme_close(struct net_device *netdev)
 
 	JME_NAPI_DISABLE(jme);
 
-	tasklet_kill(&jme->linkch_task);
+	cancel_work_sync(&jme->linkch_task);
 	tasklet_kill(&jme->txclean_task);
 	tasklet_kill(&jme->rxclean_task);
 	tasklet_kill(&jme->rxempty_task);
@@ -3035,6 +3034,7 @@ jme_init_one(struct pci_dev *pdev,
 	atomic_set(&jme->rx_empty, 1);
 
 	tasklet_setup(&jme->pcc_task, jme_pcc_tasklet);
+	INIT_WORK(&jme->linkch_task, jme_link_change_work);
 	jme->dpi.cur = PCC_P1;
 
 	jme->reg_ghc = 0;
diff --git a/drivers/net/ethernet/jme.h b/drivers/net/ethernet/jme.h
index a2c3b00d939d..2af76329b4a2 100644
--- a/drivers/net/ethernet/jme.h
+++ b/drivers/net/ethernet/jme.h
@@ -411,7 +411,7 @@ struct jme_adapter {
 	struct tasklet_struct	rxempty_task;
 	struct tasklet_struct	rxclean_task;
 	struct tasklet_struct	txclean_task;
-	struct tasklet_struct	linkch_task;
+	struct work_struct	linkch_task;
 	struct tasklet_struct	pcc_task;
 	unsigned long		flags;
 	u32			reg_txcs;
diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 71e2ada86793..72e2e71aac0e 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -251,7 +251,7 @@ void ath9k_beacon_ensure_primary_slot(struct ath_softc *sc)
 	int first_slot = ATH_BCBUF;
 	int slot;
 
-	tasklet_disable(&sc->bcon_tasklet);
+	tasklet_disable_in_atomic(&sc->bcon_tasklet);
 
 	/* Find first taken slot. */
 	for (slot = 0; slot < ATH_BCBUF; slot++) {
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 27a17a1e4a7c..a313708bcf75 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1458,7 +1458,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 	 * Prevents hv_pci_onchannelcallback() from running concurrently
 	 * in the tasklet.
 	 */
-	tasklet_disable(&channel->callback_event);
+	tasklet_disable_in_atomic(&channel->callback_event);
 
 	/*
 	 * Since this function is called with IRQ locks held, can't
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/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/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 05572e2140ad..0c56cc99e3da 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1043,6 +1043,9 @@ 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
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 6d89e33fe3aa..8cc8e5713287 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -761,7 +761,7 @@ EXPORT_SYMBOL_GPL(handle_fasteoi_nmi);
  *	handle_edge_irq - edge type IRQ handler
  *	@desc:	the interrupt description structure for this irq
  *
- *	Interrupt occures on the falling and/or rising edge of a hardware
+ *	Interrupt occurs on the falling and/or rising edge of a hardware
  *	signal. The occurrence is latched into the irq controller hardware
  *	and must be acked in order to be reenabled. After the ack another
  *	interrupt can happen on the same source even before the first one
@@ -808,7 +808,7 @@ void handle_edge_irq(struct irq_desc *desc)
 		/*
 		 * When another irq arrived while we were handling
 		 * one, we could have masked the irq.
-		 * Renable it, if it was not disabled in meantime.
+		 * Reenable it, if it was not disabled in meantime.
 		 */
 		if (unlikely(desc->istate & IRQS_PENDING)) {
 			if (!irqd_irq_disabled(&desc->irq_data) &&
@@ -1419,7 +1419,7 @@ EXPORT_SYMBOL_GPL(irq_chip_eoi_parent);
  * @dest:	The affinity mask to set
  * @force:	Flag to enforce setting (disable online checks)
  *
- * Conditinal, as the underlying parent chip might not implement it.
+ * Conditional, as the underlying parent chip might not implement it.
  */
 int irq_chip_set_affinity_parent(struct irq_data *data,
 				 const struct cpumask *dest, bool force)
@@ -1531,7 +1531,7 @@ EXPORT_SYMBOL_GPL(irq_chip_release_resources_parent);
 #endif
 
 /**
- * irq_chip_compose_msi_msg - Componse msi message for a irq chip
+ * irq_chip_compose_msi_msg - Compose msi message for a irq chip
  * @data:	Pointer to interrupt specific data
  * @msg:	Pointer to the MSI message
  *
diff --git a/kernel/irq/dummychip.c b/kernel/irq/dummychip.c
index 0b0cdf206dc4..7fe6cffe7d0d 100644
--- a/kernel/irq/dummychip.c
+++ b/kernel/irq/dummychip.c
@@ -13,7 +13,7 @@
 
 /*
  * What should we do if we get a hw irq event on an illegal vector?
- * Each architecture has to answer this themself.
+ * Each architecture has to answer this themselves.
  */
 static void ack_bad(struct irq_data *data)
 {
diff --git a/kernel/irq/ipi.c b/kernel/irq/ipi.c
index 43e3d1be622c..52f11c791bf8 100644
--- a/kernel/irq/ipi.c
+++ b/kernel/irq/ipi.c
@@ -107,7 +107,7 @@ free_descs:
  * @irq:	linux irq number to be destroyed
  * @dest:	cpumask of cpus which should have the IPI removed
  *
- * The IPIs allocated with irq_reserve_ipi() are retuerned to the system
+ * The IPIs allocated with irq_reserve_ipi() are returned to the system
  * destroying all virqs associated with them.
  *
  * Return 0 on success or error code on failure.
diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index 40880c350b95..0cd02efa3a74 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -24,10 +24,6 @@ struct irq_sim_irq_ctx {
 	struct irq_sim_work_ctx	*work_ctx;
 };
 
-struct irq_sim_devres {
-	struct irq_domain	*domain;
-};
-
 static void irq_sim_irqmask(struct irq_data *data)
 {
 	struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
@@ -216,11 +212,11 @@ void irq_domain_remove_sim(struct irq_domain *domain)
 }
 EXPORT_SYMBOL_GPL(irq_domain_remove_sim);
 
-static void devm_irq_domain_release_sim(struct device *dev, void *res)
+static void devm_irq_domain_remove_sim(void *data)
 {
-	struct irq_sim_devres *this = res;
+	struct irq_domain *domain = data;
 
-	irq_domain_remove_sim(this->domain);
+	irq_domain_remove_sim(domain);
 }
 
 /**
@@ -238,20 +234,17 @@ struct irq_domain *devm_irq_domain_create_sim(struct device *dev,
 					      struct fwnode_handle *fwnode,
 					      unsigned int num_irqs)
 {
-	struct irq_sim_devres *dr;
+	struct irq_domain *domain;
+	int ret;
 
-	dr = devres_alloc(devm_irq_domain_release_sim,
-			  sizeof(*dr), GFP_KERNEL);
-	if (!dr)
-		return ERR_PTR(-ENOMEM);
+	domain = irq_domain_create_sim(fwnode, num_irqs);
+	if (IS_ERR(domain))
+		return domain;
 
-	dr->domain = irq_domain_create_sim(fwnode, num_irqs);
-	if (IS_ERR(dr->domain)) {
-		devres_free(dr);
-		return dr->domain;
-	}
+	ret = devm_add_action_or_reset(dev, devm_irq_domain_remove_sim, domain);
+	if (ret)
+		return ERR_PTR(ret);
 
-	devres_add(dev, dr);
-	return dr->domain;
+	return domain;
 }
 EXPORT_SYMBOL_GPL(devm_irq_domain_create_sim);
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index cc1a09406c6e..4a617d7312a4 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -31,7 +31,7 @@ static int __init irq_affinity_setup(char *str)
 	cpulist_parse(str, irq_default_affinity);
 	/*
 	 * Set at least the boot cpu. We don't want to end up with
-	 * bugreports caused by random comandline masks
+	 * bugreports caused by random commandline masks
 	 */
 	cpumask_set_cpu(smp_processor_id(), irq_default_affinity);
 	return 1;
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index d10ab1d689d5..1d5d57d1ad0b 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -62,7 +62,7 @@ EXPORT_SYMBOL_GPL(irqchip_fwnode_ops);
  * @name:	Optional user provided domain name
  * @pa:		Optional user-provided physical address
  *
- * Allocate a struct irqchip_fwid, and return a poiner to the embedded
+ * Allocate a struct irqchip_fwid, and return a pointer to the embedded
  * fwnode_handle (or NULL on failure).
  *
  * Note: The types IRQCHIP_FWNODE_NAMED and IRQCHIP_FWNODE_NAMED_ID are
@@ -665,7 +665,7 @@ unsigned int irq_create_mapping_affinity(struct irq_domain *domain,
 
 	pr_debug("irq_create_mapping(0x%p, 0x%lx)\n", domain, hwirq);
 
-	/* Look for default domain if nececssary */
+	/* Look for default domain if necessary */
 	if (domain == NULL)
 		domain = irq_default_domain;
 	if (domain == NULL) {
@@ -906,7 +906,7 @@ unsigned int irq_find_mapping(struct irq_domain *domain,
 {
 	struct irq_data *data;
 
-	/* Look for default domain if nececssary */
+	/* Look for default domain if necessary */
 	if (domain == NULL)
 		domain = irq_default_domain;
 	if (domain == NULL)
@@ -1436,7 +1436,7 @@ int irq_domain_alloc_irqs_hierarchy(struct irq_domain *domain,
  * The whole process to setup an IRQ has been split into two steps.
  * The first step, __irq_domain_alloc_irqs(), is to allocate IRQ
  * descriptor and required hardware resources. The second step,
- * irq_domain_activate_irq(), is to program hardwares with preallocated
+ * irq_domain_activate_irq(), is to program the hardware with preallocated
  * resources. In this way, it's easier to rollback when failing to
  * allocate resources.
  */
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 21ea370fccda..4c14356543d9 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -179,7 +179,7 @@ bool irq_can_set_affinity_usr(unsigned int irq)
 
 /**
  *	irq_set_thread_affinity - Notify irq threads to adjust affinity
- *	@desc:		irq descriptor which has affitnity changed
+ *	@desc:		irq descriptor which has affinity changed
  *
  *	We just set IRQTF_AFFINITY and delegate the affinity setting
  *	to the interrupt thread itself. We can not call
@@ -326,7 +326,7 @@ static bool irq_set_affinity_deactivated(struct irq_data *data,
 	 * If the interrupt is not yet activated, just store the affinity
 	 * mask and do not call the chip driver at all. On activation the
 	 * driver has to make sure anyway that the interrupt is in a
-	 * useable state so startup works.
+	 * usable state so startup works.
 	 */
 	if (!IS_ENABLED(CONFIG_IRQ_DOMAIN_HIERARCHY) ||
 	    irqd_is_activated(data) || !irqd_affinity_on_activate(data))
@@ -1054,7 +1054,7 @@ again:
 	 * to IRQS_INPROGRESS and the irq line is masked forever.
 	 *
 	 * This also serializes the state of shared oneshot handlers
-	 * versus "desc->threads_onehsot |= action->thread_mask;" in
+	 * versus "desc->threads_oneshot |= action->thread_mask;" in
 	 * irq_wake_thread(). See the comment there which explains the
 	 * serialization.
 	 */
@@ -1157,7 +1157,7 @@ irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
 
 /*
  * Interrupts explicitly requested as threaded interrupts want to be
- * preemtible - many of them need to sleep and wait for slow busses to
+ * preemptible - many of them need to sleep and wait for slow busses to
  * complete.
  */
 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
@@ -1697,7 +1697,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 			irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
 		}
 
-		if (irq_settings_can_autoenable(desc)) {
+		if (!(new->flags & IRQF_NO_AUTOEN) &&
+		    irq_settings_can_autoenable(desc)) {
 			irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
 		} else {
 			/*
@@ -1912,7 +1913,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
 	/* Last action releases resources */
 	if (!desc->action) {
 		/*
-		 * Reaquire bus lock as irq_release_resources() might
+		 * Reacquire bus lock as irq_release_resources() might
 		 * require it to deallocate resources over the slow bus.
 		 */
 		chip_bus_lock(desc);
@@ -2090,10 +2091,15 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
 	 * which interrupt is which (messes up the interrupt freeing
 	 * logic etc).
 	 *
+	 * Also shared interrupts do not go well with disabling auto enable.
+	 * The sharing interrupt might request it while it's still disabled
+	 * and then wait for interrupts forever.
+	 *
 	 * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and
 	 * it cannot be set along with IRQF_NO_SUSPEND.
 	 */
 	if (((irqflags & IRQF_SHARED) && !dev_id) ||
+	    ((irqflags & IRQF_SHARED) && (irqflags & IRQF_NO_AUTOEN)) ||
 	    (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
 	    ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
 		return -EINVAL;
@@ -2249,7 +2255,8 @@ int request_nmi(unsigned int irq, irq_handler_t handler,
 
 	desc = irq_to_desc(irq);
 
-	if (!desc || irq_settings_can_autoenable(desc) ||
+	if (!desc || (irq_settings_can_autoenable(desc) &&
+	    !(irqflags & IRQF_NO_AUTOEN)) ||
 	    !irq_settings_can_request(desc) ||
 	    WARN_ON(irq_settings_is_per_cpu_devid(desc)) ||
 	    !irq_supports_nmi(desc))
@@ -2746,7 +2753,7 @@ int __irq_get_irqchip_state(struct irq_data *data, enum irqchip_irq_state which,
  *	irq_get_irqchip_state - returns the irqchip state of a interrupt.
  *	@irq: Interrupt line that is forwarded to a VM
  *	@which: One of IRQCHIP_STATE_* the caller wants to know about
- *	@state: a pointer to a boolean where the state is to be storeed
+ *	@state: a pointer to a boolean where the state is to be stored
  *
  *	This call snapshots the internal irqchip state of an
  *	interrupt, returning into @state the bit corresponding to
diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
index 651a4ad6d711..578596e41cb6 100644
--- a/kernel/irq/matrix.c
+++ b/kernel/irq/matrix.c
@@ -337,15 +337,14 @@ void irq_matrix_assign(struct irq_matrix *m, unsigned int bit)
  * irq_matrix_reserve - Reserve interrupts
  * @m:		Matrix pointer
  *
- * This is merily a book keeping call. It increments the number of globally
+ * This is merely a book keeping call. It increments the number of globally
  * reserved interrupt bits w/o actually allocating them. This allows to
  * setup interrupt descriptors w/o assigning low level resources to it.
  * The actual allocation happens when the interrupt gets activated.
  */
 void irq_matrix_reserve(struct irq_matrix *m)
 {
-	if (m->global_reserved <= m->global_available &&
-	    m->global_reserved + 1 > m->global_available)
+	if (m->global_reserved == m->global_available)
 		pr_warn("Interrupt reservation exceeds available resources\n");
 
 	m->global_reserved++;
@@ -356,7 +355,7 @@ void irq_matrix_reserve(struct irq_matrix *m)
  * irq_matrix_remove_reserved - Remove interrupt reservation
  * @m:		Matrix pointer
  *
- * This is merily a book keeping call. It decrements the number of globally
+ * This is merely a book keeping call. It decrements the number of globally
  * reserved interrupt bits. This is used to undo irq_matrix_reserve() when the
  * interrupt was never in use and a real vector allocated, which undid the
  * reservation.
@@ -423,7 +422,9 @@ void irq_matrix_free(struct irq_matrix *m, unsigned int cpu,
 	if (WARN_ON_ONCE(bit < m->alloc_start || bit >= m->alloc_end))
 		return;
 
-	clear_bit(bit, cm->alloc_map);
+	if (WARN_ON_ONCE(!test_and_clear_bit(bit, cm->alloc_map)))
+		return;
+
 	cm->allocated--;
 	if(managed)
 		cm->managed_allocated--;
diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
index def48589ea48..61ca924ef4b4 100644
--- a/kernel/irq/migration.c
+++ b/kernel/irq/migration.c
@@ -7,7 +7,7 @@
 
 /**
  * irq_fixup_move_pending - Cleanup irq move pending from a dying CPU
- * @desc:		Interrupt descpriptor to clean up
+ * @desc:		Interrupt descriptor to clean up
  * @force_clear:	If set clear the move pending bit unconditionally.
  *			If not set, clear it only when the dying CPU is the
  *			last one in the pending mask.
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index b338d622f26e..c41965e348b5 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -5,7 +5,7 @@
  *
  * This file is licensed under GPLv2.
  *
- * This file contains common code to support Message Signalled Interrupt for
+ * This file contains common code to support Message Signaled Interrupts for
  * PCI compatible and non PCI compatible devices.
  */
 #include <linux/types.h>
diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
index bd1d85c610aa..0c46e9fe3a89 100644
--- a/kernel/irq/resend.c
+++ b/kernel/irq/resend.c
@@ -128,7 +128,7 @@ int check_irq_resend(struct irq_desc *desc, bool inject)
 	if (!try_retrigger(desc))
 		err = irq_sw_resend(desc);
 
-	/* If the retrigger was successfull, mark it with the REPLAY bit */
+	/* If the retrigger was successful, mark it with the REPLAY bit */
 	if (!err)
 		desc->istate |= IRQS_REPLAY;
 	return err;
diff --git a/kernel/irq/timings.c b/kernel/irq/timings.c
index 773b6105c4ae..d309d6fbf5bd 100644
--- a/kernel/irq/timings.c
+++ b/kernel/irq/timings.c
@@ -84,7 +84,7 @@ void irq_timings_disable(void)
  * 2. Log interval
  *
  * We saw the irq timings allow to compute the interval of the
- * occurrences for a specific interrupt. We can reasonibly assume the
+ * occurrences for a specific interrupt. We can reasonably assume the
  * longer is the interval, the higher is the error for the next event
  * and we can consider storing those interval values into an array
  * where each slot in the array correspond to an interval at the power
@@ -416,7 +416,7 @@ static u64 __irq_timings_next_event(struct irqt_stat *irqs, int irq, u64 now)
 	 * Copy the content of the circular buffer into another buffer
 	 * in order to linearize the buffer instead of dealing with
 	 * wrapping indexes and shifted array which will be prone to
-	 * error and extremelly difficult to debug.
+	 * error and extremely difficult to debug.
 	 */
 	for (i = 0; i < count; i++) {
 		int index = (start + i) & IRQ_TIMINGS_MASK;
@@ -485,7 +485,7 @@ static inline void irq_timings_store(int irq, struct irqt_stat *irqs, u64 ts)
 
 	/*
 	 * The interrupt triggered more than one second apart, that
-	 * ends the sequence as predictible for our purpose. In this
+	 * ends the sequence as predictable for our purpose. In this
 	 * case, assume we have the beginning of a sequence and the
 	 * timestamp is the first value. As it is impossible to
 	 * predict anything at this point, return.
@@ -514,7 +514,7 @@ static inline void irq_timings_store(int irq, struct irqt_stat *irqs, u64 ts)
  *      If more than the array size interrupts happened during the
  *      last busy/idle cycle, the index wrapped up and we have to
  *      begin with the next element in the array which is the last one
- *      in the sequence, otherwise it is a the index 0.
+ *      in the sequence, otherwise it is at the index 0.
  *
  * - have an indication of the interrupts activity on this CPU
  *   (eg. irq/sec)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 3b36644fa80a..872e481d5098 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -60,7 +60,7 @@ void irqtime_account_irq(struct task_struct *curr, unsigned int offset)
 	cpu = smp_processor_id();
 	delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
 	irqtime->irq_start_time += delta;
-	pc = preempt_count() - offset;
+	pc = irq_count() - offset;
 
 	/*
 	 * We do not account for softirq time from ksoftirqd here.
@@ -421,7 +421,7 @@ void vtime_task_switch(struct task_struct *prev)
 
 void vtime_account_irq(struct task_struct *tsk, unsigned int offset)
 {
-	unsigned int pc = preempt_count() - offset;
+	unsigned int pc = irq_count() - offset;
 
 	if (pc & HARDIRQ_OFFSET) {
 		vtime_account_hardirq(tsk);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 9908ec4a9bfe..5a99696da86a 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -13,6 +13,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
+#include <linux/local_lock.h>
 #include <linux/mm.h>
 #include <linux/notifier.h>
 #include <linux/percpu.h>
@@ -25,6 +26,7 @@
 #include <linux/smpboot.h>
 #include <linux/tick.h>
 #include <linux/irq.h>
+#include <linux/wait_bit.h>
 
 #include <asm/softirq_stack.h>
 
@@ -102,20 +104,204 @@ EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context);
 #endif
 
 /*
- * preempt_count and SOFTIRQ_OFFSET usage:
- * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
- *   softirq processing.
- * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
+ * SOFTIRQ_OFFSET usage:
+ *
+ * On !RT kernels 'count' is the preempt counter, on RT kernels this applies
+ * to a per CPU counter and to task::softirqs_disabled_cnt.
+ *
+ * - count is changed by SOFTIRQ_OFFSET on entering or leaving softirq
+ *   processing.
+ *
+ * - count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
  *   on local_bh_disable or local_bh_enable.
+ *
  * This lets us distinguish between whether we are currently processing
  * softirq and whether we just have bh disabled.
  */
+#ifdef CONFIG_PREEMPT_RT
+
+/*
+ * RT accounts for BH disabled sections in task::softirqs_disabled_cnt and
+ * also in per CPU softirq_ctrl::cnt. This is necessary to allow tasks in a
+ * softirq disabled section to be preempted.
+ *
+ * The per task counter is used for softirq_count(), in_softirq() and
+ * in_serving_softirqs() because these counts are only valid when the task
+ * holding softirq_ctrl::lock is running.
+ *
+ * The per CPU counter prevents pointless wakeups of ksoftirqd in case that
+ * the task which is in a softirq disabled section is preempted or blocks.
+ */
+struct softirq_ctrl {
+	local_lock_t	lock;
+	int		cnt;
+};
+
+static DEFINE_PER_CPU(struct softirq_ctrl, softirq_ctrl) = {
+	.lock	= INIT_LOCAL_LOCK(softirq_ctrl.lock),
+};
+
+/**
+ * local_bh_blocked() - Check for idle whether BH processing is blocked
+ *
+ * Returns false if the per CPU softirq::cnt is 0 otherwise true.
+ *
+ * This is invoked from the idle task to guard against false positive
+ * softirq pending warnings, which would happen when the task which holds
+ * softirq_ctrl::lock was the only running task on the CPU and blocks on
+ * some other lock.
+ */
+bool local_bh_blocked(void)
+{
+	return __this_cpu_read(softirq_ctrl.cnt) != 0;
+}
+
+void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
+{
+	unsigned long flags;
+	int newcnt;
+
+	WARN_ON_ONCE(in_hardirq());
+
+	/* First entry of a task into a BH disabled section? */
+	if (!current->softirq_disable_cnt) {
+		if (preemptible()) {
+			local_lock(&softirq_ctrl.lock);
+			/* Required to meet the RCU bottomhalf requirements. */
+			rcu_read_lock();
+		} else {
+			DEBUG_LOCKS_WARN_ON(this_cpu_read(softirq_ctrl.cnt));
+		}
+	}
+
+	/*
+	 * Track the per CPU softirq disabled state. On RT this is per CPU
+	 * state to allow preemption of bottom half disabled sections.
+	 */
+	newcnt = __this_cpu_add_return(softirq_ctrl.cnt, cnt);
+	/*
+	 * Reflect the result in the task state to prevent recursion on the
+	 * local lock and to make softirq_count() & al work.
+	 */
+	current->softirq_disable_cnt = newcnt;
+
+	if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS) && newcnt == cnt) {
+		raw_local_irq_save(flags);
+		lockdep_softirqs_off(ip);
+		raw_local_irq_restore(flags);
+	}
+}
+EXPORT_SYMBOL(__local_bh_disable_ip);
+
+static void __local_bh_enable(unsigned int cnt, bool unlock)
+{
+	unsigned long flags;
+	int newcnt;
+
+	DEBUG_LOCKS_WARN_ON(current->softirq_disable_cnt !=
+			    this_cpu_read(softirq_ctrl.cnt));
+
+	if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS) && softirq_count() == cnt) {
+		raw_local_irq_save(flags);
+		lockdep_softirqs_on(_RET_IP_);
+		raw_local_irq_restore(flags);
+	}
+
+	newcnt = __this_cpu_sub_return(softirq_ctrl.cnt, cnt);
+	current->softirq_disable_cnt = newcnt;
+
+	if (!newcnt && unlock) {
+		rcu_read_unlock();
+		local_unlock(&softirq_ctrl.lock);
+	}
+}
+
+void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
+{
+	bool preempt_on = preemptible();
+	unsigned long flags;
+	u32 pending;
+	int curcnt;
+
+	WARN_ON_ONCE(in_irq());
+	lockdep_assert_irqs_enabled();
+
+	local_irq_save(flags);
+	curcnt = __this_cpu_read(softirq_ctrl.cnt);
+
+	/*
+	 * If this is not reenabling soft interrupts, no point in trying to
+	 * run pending ones.
+	 */
+	if (curcnt != cnt)
+		goto out;
+
+	pending = local_softirq_pending();
+	if (!pending || ksoftirqd_running(pending))
+		goto out;
+
+	/*
+	 * If this was called from non preemptible context, wake up the
+	 * softirq daemon.
+	 */
+	if (!preempt_on) {
+		wakeup_softirqd();
+		goto out;
+	}
+
+	/*
+	 * Adjust softirq count to SOFTIRQ_OFFSET which makes
+	 * in_serving_softirq() become true.
+	 */
+	cnt = SOFTIRQ_OFFSET;
+	__local_bh_enable(cnt, false);
+	__do_softirq();
+
+out:
+	__local_bh_enable(cnt, preempt_on);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(__local_bh_enable_ip);
+
+/*
+ * Invoked from ksoftirqd_run() outside of the interrupt disabled section
+ * to acquire the per CPU local lock for reentrancy protection.
+ */
+static inline void ksoftirqd_run_begin(void)
+{
+	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
+	local_irq_disable();
+}
+
+/* Counterpart to ksoftirqd_run_begin() */
+static inline void ksoftirqd_run_end(void)
+{
+	__local_bh_enable(SOFTIRQ_OFFSET, true);
+	WARN_ON_ONCE(in_interrupt());
+	local_irq_enable();
+}
+
+static inline void softirq_handle_begin(void) { }
+static inline void softirq_handle_end(void) { }
+
+static inline bool should_wake_ksoftirqd(void)
+{
+	return !this_cpu_read(softirq_ctrl.cnt);
+}
+
+static inline void invoke_softirq(void)
+{
+	if (should_wake_ksoftirqd())
+		wakeup_softirqd();
+}
+
+#else /* CONFIG_PREEMPT_RT */
 
-#ifdef CONFIG_TRACE_IRQFLAGS
 /*
- * This is for softirq.c-internal use, where hardirqs are disabled
+ * This one is for softirq.c-internal use, where hardirqs are disabled
  * legitimately:
  */
+#ifdef CONFIG_TRACE_IRQFLAGS
 void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
 {
 	unsigned long flags;
@@ -206,6 +392,32 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
 }
 EXPORT_SYMBOL(__local_bh_enable_ip);
 
+static inline void softirq_handle_begin(void)
+{
+	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
+}
+
+static inline void softirq_handle_end(void)
+{
+	__local_bh_enable(SOFTIRQ_OFFSET);
+	WARN_ON_ONCE(in_interrupt());
+}
+
+static inline void ksoftirqd_run_begin(void)
+{
+	local_irq_disable();
+}
+
+static inline void ksoftirqd_run_end(void)
+{
+	local_irq_enable();
+}
+
+static inline bool should_wake_ksoftirqd(void)
+{
+	return true;
+}
+
 static inline void invoke_softirq(void)
 {
 	if (ksoftirqd_running(local_softirq_pending()))
@@ -250,6 +462,8 @@ asmlinkage __visible void do_softirq(void)
 	local_irq_restore(flags);
 }
 
+#endif /* !CONFIG_PREEMPT_RT */
+
 /*
  * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
  * but break the loop if need_resched() is set or after 2 ms.
@@ -318,7 +532,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 
 	pending = local_softirq_pending();
 
-	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
+	softirq_handle_begin();
 	in_hardirq = lockdep_softirq_start();
 	account_softirq_enter(current);
 
@@ -354,8 +568,10 @@ restart:
 		pending >>= softirq_bit;
 	}
 
-	if (__this_cpu_read(ksoftirqd) == current)
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT) &&
+	    __this_cpu_read(ksoftirqd) == current)
 		rcu_softirq_qs();
+
 	local_irq_disable();
 
 	pending = local_softirq_pending();
@@ -369,8 +585,7 @@ restart:
 
 	account_softirq_exit(current);
 	lockdep_softirq_end(in_hardirq);
-	__local_bh_enable(SOFTIRQ_OFFSET);
-	WARN_ON_ONCE(in_interrupt());
+	softirq_handle_end();
 	current_restore_flags(old_flags, PF_MEMALLOC);
 }
 
@@ -465,7 +680,7 @@ inline void raise_softirq_irqoff(unsigned int nr)
 	 * Otherwise we wake up ksoftirqd to make sure we
 	 * schedule the softirq soon.
 	 */
-	if (!in_interrupt())
+	if (!in_interrupt() && should_wake_ksoftirqd())
 		wakeup_softirqd();
 }
 
@@ -531,6 +746,20 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
 }
 EXPORT_SYMBOL(__tasklet_hi_schedule);
 
+static bool tasklet_clear_sched(struct tasklet_struct *t)
+{
+	if (test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) {
+		wake_up_var(&t->state);
+		return true;
+	}
+
+	WARN_ONCE(1, "tasklet SCHED state not set: %s %pS\n",
+		  t->use_callback ? "callback" : "func",
+		  t->use_callback ? (void *)t->callback : (void *)t->func);
+
+	return false;
+}
+
 static void tasklet_action_common(struct softirq_action *a,
 				  struct tasklet_head *tl_head,
 				  unsigned int softirq_nr)
@@ -550,13 +779,12 @@ static void tasklet_action_common(struct softirq_action *a,
 
 		if (tasklet_trylock(t)) {
 			if (!atomic_read(&t->count)) {
-				if (!test_and_clear_bit(TASKLET_STATE_SCHED,
-							&t->state))
-					BUG();
-				if (t->use_callback)
-					t->callback(t);
-				else
-					t->func(t->data);
+				if (tasklet_clear_sched(t)) {
+					if (t->use_callback)
+						t->callback(t);
+					else
+						t->func(t->data);
+				}
 				tasklet_unlock(t);
 				continue;
 			}
@@ -606,21 +834,62 @@ void tasklet_init(struct tasklet_struct *t,
 }
 EXPORT_SYMBOL(tasklet_init);
 
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
+/*
+ * Do not use in new code. Waiting for tasklets from atomic contexts is
+ * error prone and should be avoided.
+ */
+void tasklet_unlock_spin_wait(struct tasklet_struct *t)
+{
+	while (test_bit(TASKLET_STATE_RUN, &(t)->state)) {
+		if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+			/*
+			 * Prevent a live lock when current preempted soft
+			 * interrupt processing or prevents ksoftirqd from
+			 * running. If the tasklet runs on a different CPU
+			 * then this has no effect other than doing the BH
+			 * disable/enable dance for nothing.
+			 */
+			local_bh_disable();
+			local_bh_enable();
+		} else {
+			cpu_relax();
+		}
+	}
+}
+EXPORT_SYMBOL(tasklet_unlock_spin_wait);
+#endif
+
 void tasklet_kill(struct tasklet_struct *t)
 {
 	if (in_interrupt())
 		pr_notice("Attempt to kill tasklet from interrupt\n");
 
-	while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
-		do {
-			yield();
-		} while (test_bit(TASKLET_STATE_SCHED, &t->state));
-	}
+	while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
+		wait_var_event(&t->state, !test_bit(TASKLET_STATE_SCHED, &t->state));
+
 	tasklet_unlock_wait(t);
-	clear_bit(TASKLET_STATE_SCHED, &t->state);
+	tasklet_clear_sched(t);
 }
 EXPORT_SYMBOL(tasklet_kill);
 
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
+void tasklet_unlock(struct tasklet_struct *t)
+{
+	smp_mb__before_atomic();
+	clear_bit(TASKLET_STATE_RUN, &t->state);
+	smp_mb__after_atomic();
+	wake_up_var(&t->state);
+}
+EXPORT_SYMBOL_GPL(tasklet_unlock);
+
+void tasklet_unlock_wait(struct tasklet_struct *t)
+{
+	wait_var_event(&t->state, !test_bit(TASKLET_STATE_RUN, &t->state));
+}
+EXPORT_SYMBOL_GPL(tasklet_unlock_wait);
+#endif
+
 void __init softirq_init(void)
 {
 	int cpu;
@@ -643,53 +912,21 @@ static int ksoftirqd_should_run(unsigned int cpu)
 
 static void run_ksoftirqd(unsigned int cpu)
 {
-	local_irq_disable();
+	ksoftirqd_run_begin();
 	if (local_softirq_pending()) {
 		/*
 		 * We can safely run softirq on inline stack, as we are not deep
 		 * in the task stack here.
 		 */
 		__do_softirq();
-		local_irq_enable();
+		ksoftirqd_run_end();
 		cond_resched();
 		return;
 	}
-	local_irq_enable();
+	ksoftirqd_run_end();
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-/*
- * tasklet_kill_immediate is called to remove a tasklet which can already be
- * scheduled for execution on @cpu.
- *
- * Unlike tasklet_kill, this function removes the tasklet
- * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state.
- *
- * When this function is called, @cpu must be in the CPU_DEAD state.
- */
-void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
-{
-	struct tasklet_struct **i;
-
-	BUG_ON(cpu_online(cpu));
-	BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state));
-
-	if (!test_bit(TASKLET_STATE_SCHED, &t->state))
-		return;
-
-	/* CPU is dead, so no lock needed. */
-	for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
-		if (*i == t) {
-			*i = t->next;
-			/* If this was the tail element, move the tail ptr */
-			if (*i == NULL)
-				per_cpu(tasklet_vec, cpu).tail = i;
-			return;
-		}
-	}
-	BUG();
-}
-
 static int takeover_tasklets(unsigned int cpu)
 {
 	/* CPU is dead, so no lock needed. */
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 128735e3e77e..d34894f3862a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -973,7 +973,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
 	if (unlikely(local_softirq_pending())) {
 		static int ratelimit;
 
-		if (ratelimit < 10 &&
+		if (ratelimit < 10 && !local_bh_blocked() &&
 		    (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
 			pr_warn("NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #%02x!!!\n",
 				(unsigned int) local_softirq_pending());