[IA64] hotplug/ia64: SN Hotplug Driver: SN IRQ Fixes

This patch  fixes the SN IRQ code such that cpu affinity and
Hotplug can modify IRQ values.  The sn_irq_info structures are now locked
using a RCU lock mechanism to avoid lock contention in the lost interrupt
WAR code.
Signed-off-by: Prarit Bhargava <prarit@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/sn/kernel/io_init.c

@@ -21,7 +21,6 @@
 #include <asm/sn/simulator.h>
 #include <asm/sn/tioca_provider.h>
 
-char master_baseio_wid;
 nasid_t master_nasid = INVALID_NASID;	/* Partition Master */
 
 struct slab_info {
@@ -231,11 +230,13 @@ static void sn_pci_fixup_slot(struct pci_dev *dev)
 {
 	int idx;
 	int segment = 0;
-	uint64_t size;
-	struct sn_irq_info *sn_irq_info;
-	struct pci_dev *host_pci_dev;
 	int status = 0;
 	struct pcibus_bussoft *bs;
+ 	struct pci_bus *host_pci_bus;
+ 	struct pci_dev *host_pci_dev;
+ 	struct sn_irq_info *sn_irq_info;
+ 	unsigned long size;
+ 	unsigned int bus_no, devfn;
 
 	dev->sysdata = kmalloc(sizeof(struct pcidev_info), GFP_KERNEL);
 	if (SN_PCIDEV_INFO(dev) <= 0)
@@ -253,7 +254,7 @@ static void sn_pci_fixup_slot(struct pci_dev *dev)
 				     (u64) __pa(SN_PCIDEV_INFO(dev)),
 				     (u64) __pa(sn_irq_info));
 	if (status)
-		BUG();		/* Cannot get platform pci device information information */
+		BUG(); /* Cannot get platform pci device information */
 
 	/* Copy over PIO Mapped Addresses */
 	for (idx = 0; idx <= PCI_ROM_RESOURCE; idx++) {
@@ -275,15 +276,20 @@ static void sn_pci_fixup_slot(struct pci_dev *dev)
 			dev->resource[idx].parent = &iomem_resource;
 	}
 
-	/* set up host bus linkages */
-	bs = SN_PCIBUS_BUSSOFT(dev->bus);
-	host_pci_dev =
-	    pci_find_slot(SN_PCIDEV_INFO(dev)->pdi_slot_host_handle >> 32,
-			  SN_PCIDEV_INFO(dev)->
-			  pdi_slot_host_handle & 0xffffffff);
+ 	/* Using the PROMs values for the PCI host bus, get the Linux
+ 	 * PCI host_pci_dev struct and set up host bus linkages
+ 	 */
+
+ 	bus_no = SN_PCIDEV_INFO(dev)->pdi_slot_host_handle >> 32;
+ 	devfn = SN_PCIDEV_INFO(dev)->pdi_slot_host_handle & 0xffffffff;
+ 	host_pci_bus = pci_find_bus(pci_domain_nr(dev->bus), bus_no);
+ 	host_pci_dev = pci_get_slot(host_pci_bus, devfn);
+
+	SN_PCIDEV_INFO(dev)->host_pci_dev = host_pci_dev;
 	SN_PCIDEV_INFO(dev)->pdi_host_pcidev_info =
 	    					SN_PCIDEV_INFO(host_pci_dev);
 	SN_PCIDEV_INFO(dev)->pdi_linux_pcidev = dev;
+	bs = SN_PCIBUS_BUSSOFT(dev->bus);
 	SN_PCIDEV_INFO(dev)->pdi_pcibus_info = bs;
 
 	if (bs && bs->bs_asic_type < PCIIO_ASIC_MAX_TYPES) {
@@ -297,6 +303,9 @@ static void sn_pci_fixup_slot(struct pci_dev *dev)
 		SN_PCIDEV_INFO(dev)->pdi_sn_irq_info = sn_irq_info;
 		dev->irq = SN_PCIDEV_INFO(dev)->pdi_sn_irq_info->irq_irq;
 		sn_irq_fixup(dev, sn_irq_info);
+	} else {
+		SN_PCIDEV_INFO(dev)->pdi_sn_irq_info = NULL;
+		kfree(sn_irq_info);
 	}
 }
 
@@ -403,11 +412,7 @@ static int __init sn_pci_init(void)
 	 */
 	ia64_max_iommu_merge_mask = ~PAGE_MASK;
 	sn_fixup_ionodes();
-	sn_irq = kmalloc(sizeof(struct sn_irq_info *) * NR_IRQS, GFP_KERNEL);
-	if (sn_irq <= 0)
-		BUG();		/* Canno afford to run out of memory. */
-	memset(sn_irq, 0, sizeof(struct sn_irq_info *) * NR_IRQS);
-
+	sn_irq_lh_init();
 	sn_init_cpei_timer();
 
 #ifdef CONFIG_PROC_FS

arch/ia64/sn/kernel/irq.c

@@ -9,6 +9,7 @@
  */
 
 #include <linux/irq.h>
+#include <linux/spinlock.h>
 #include <asm/sn/intr.h>
 #include <asm/sn/addrs.h>
 #include <asm/sn/arch.h>
@@ -25,7 +26,8 @@ static void unregister_intr_pda(struct sn_irq_info *sn_irq_info);
 
 extern int sn_force_interrupt_flag;
 extern int sn_ioif_inited;
-struct sn_irq_info **sn_irq;
+static struct list_head **sn_irq_lh;
+static spinlock_t sn_irq_info_lock = SPIN_LOCK_UNLOCKED; /* non-IRQ lock */
 
 static inline uint64_t sn_intr_alloc(nasid_t local_nasid, int local_widget,
 				     u64 sn_irq_info,
@@ -115,82 +117,84 @@ static void sn_end_irq(unsigned int irq)
 		force_interrupt(irq);
 }
 
+static void sn_irq_info_free(struct rcu_head *head);
+
 static void sn_set_affinity_irq(unsigned int irq, cpumask_t mask)
 {
-	struct sn_irq_info *sn_irq_info = sn_irq[irq];
-	struct sn_irq_info *tmp_sn_irq_info;
+	struct sn_irq_info *sn_irq_info, *sn_irq_info_safe;
 	int cpuid, cpuphys;
-	nasid_t t_nasid;	/* nasid to target */
-	int t_slice;		/* slice to target */
-
-	/* allocate a temp sn_irq_info struct to get new target info */
-	tmp_sn_irq_info = kmalloc(sizeof(*tmp_sn_irq_info), GFP_KERNEL);
-	if (!tmp_sn_irq_info)
-		return;
 
 	cpuid = first_cpu(mask);
 	cpuphys = cpu_physical_id(cpuid);
-	t_nasid = cpuid_to_nasid(cpuid);
-	t_slice = cpuid_to_slice(cpuid);
 
-	while (sn_irq_info) {
-		int status;
-		int local_widget;
-		uint64_t bridge = (uint64_t) sn_irq_info->irq_bridge;
-		nasid_t local_nasid = NASID_GET(bridge);
+	list_for_each_entry_safe(sn_irq_info, sn_irq_info_safe,
+				 sn_irq_lh[irq], list) {
+		uint64_t bridge;
+		int local_widget, status;
+		nasid_t local_nasid;
+		struct sn_irq_info *new_irq_info;
+
+		new_irq_info = kmalloc(sizeof(struct sn_irq_info), GFP_ATOMIC);
+		if (new_irq_info == NULL)
+			break;
+		memcpy(new_irq_info, sn_irq_info, sizeof(struct sn_irq_info));
 
-		if (!bridge)
+		bridge = (uint64_t) new_irq_info->irq_bridge;
+		if (!bridge) {
+			kfree(new_irq_info);
 			break; /* irq is not a device interrupt */
+		}
+
+		local_nasid = NASID_GET(bridge);
 
 		if (local_nasid & 1)
 			local_widget = TIO_SWIN_WIDGETNUM(bridge);
 		else
 			local_widget = SWIN_WIDGETNUM(bridge);
 
-		/* Free the old PROM sn_irq_info structure */
-		sn_intr_free(local_nasid, local_widget, sn_irq_info);
+		/* Free the old PROM new_irq_info structure */
+		sn_intr_free(local_nasid, local_widget, new_irq_info);
+		/* Update kernels new_irq_info with new target info */
+		unregister_intr_pda(new_irq_info);
 
-		/* allocate a new PROM sn_irq_info struct */
+		/* allocate a new PROM new_irq_info struct */
 		status = sn_intr_alloc(local_nasid, local_widget,
-				       __pa(tmp_sn_irq_info), irq, t_nasid,
-				       t_slice);
+				       __pa(new_irq_info), irq,
+				       cpuid_to_nasid(cpuid),
+				       cpuid_to_slice(cpuid));
 
-		if (status == 0) {
-			/* Update kernels sn_irq_info with new target info */
-			unregister_intr_pda(sn_irq_info);
-			sn_irq_info->irq_cpuid = cpuid;
-			sn_irq_info->irq_nasid = t_nasid;
-			sn_irq_info->irq_slice = t_slice;
-			sn_irq_info->irq_xtalkaddr =
-			    tmp_sn_irq_info->irq_xtalkaddr;
-			sn_irq_info->irq_cookie = tmp_sn_irq_info->irq_cookie;
-			register_intr_pda(sn_irq_info);
-
-			if (IS_PCI_BRIDGE_ASIC(sn_irq_info->irq_bridge_type)) {
-				pcibr_change_devices_irq(sn_irq_info);
+		/* SAL call failed */
+		if (status) {
+			kfree(new_irq_info);
+			break;
 		}
 
-			sn_irq_info = sn_irq_info->irq_next;
+		new_irq_info->irq_cpuid = cpuid;
+		register_intr_pda(new_irq_info);
+
+		if (IS_PCI_BRIDGE_ASIC(new_irq_info->irq_bridge_type))
+			pcibr_change_devices_irq(new_irq_info);
+
+		spin_lock(&sn_irq_info_lock);
+		list_replace_rcu(&sn_irq_info->list, &new_irq_info->list);
+		spin_unlock(&sn_irq_info_lock);
+		call_rcu(&sn_irq_info->rcu, sn_irq_info_free);
 
 #ifdef CONFIG_SMP
 		set_irq_affinity_info((irq & 0xff), cpuphys, 0);
 #endif
-		} else {
-			break;	/* snp_affinity failed the intr_alloc */
 	}
-	}
-	kfree(tmp_sn_irq_info);
 }
 
 struct hw_interrupt_type irq_type_sn = {
-	"SN hub",
-	sn_startup_irq,
-	sn_shutdown_irq,
-	sn_enable_irq,
-	sn_disable_irq,
-	sn_ack_irq,
-	sn_end_irq,
-	sn_set_affinity_irq
+	.typename	= "SN hub",
+	.startup	= sn_startup_irq,
+	.shutdown	= sn_shutdown_irq,
+	.enable		= sn_enable_irq,
+	.disable	= sn_disable_irq,
+	.ack		= sn_ack_irq,
+	.end		= sn_end_irq,
+	.set_affinity	= sn_set_affinity_irq
 };
 
 unsigned int sn_local_vector_to_irq(u8 vector)
@@ -231,19 +235,18 @@ static void unregister_intr_pda(struct sn_irq_info *sn_irq_info)
 	struct sn_irq_info *tmp_irq_info;
 	int i, foundmatch;
 
+	rcu_read_lock();
 	if (pdacpu(cpu)->sn_last_irq == irq) {
 		foundmatch = 0;
-		for (i = pdacpu(cpu)->sn_last_irq - 1; i; i--) {
-			tmp_irq_info = sn_irq[i];
-			while (tmp_irq_info) {
+		for (i = pdacpu(cpu)->sn_last_irq - 1;
+		     i && !foundmatch; i--) {
+			list_for_each_entry_rcu(tmp_irq_info,
+						sn_irq_lh[i],
+						list) {
 				if (tmp_irq_info->irq_cpuid == cpu) {
-					foundmatch++;
+					foundmatch = 1;
 					break;
 				}
-				tmp_irq_info = tmp_irq_info->irq_next;
-			}
-			if (foundmatch) {
-				break;
 			}
 		}
 		pdacpu(cpu)->sn_last_irq = i;
@@ -251,60 +254,27 @@ static void unregister_intr_pda(struct sn_irq_info *sn_irq_info)
 
 	if (pdacpu(cpu)->sn_first_irq == irq) {
 		foundmatch = 0;
-		for (i = pdacpu(cpu)->sn_first_irq + 1; i < NR_IRQS; i++) {
-			tmp_irq_info = sn_irq[i];
-			while (tmp_irq_info) {
+		for (i = pdacpu(cpu)->sn_first_irq + 1;
+		     i < NR_IRQS && !foundmatch; i++) {
+			list_for_each_entry_rcu(tmp_irq_info,
+						sn_irq_lh[i],
+						list) {
 				if (tmp_irq_info->irq_cpuid == cpu) {
-					foundmatch++;
+					foundmatch = 1;
 					break;
 				}
-				tmp_irq_info = tmp_irq_info->irq_next;
-			}
-			if (foundmatch) {
-				break;
 			}
 		}
 		pdacpu(cpu)->sn_first_irq = ((i == NR_IRQS) ? 0 : i);
 	}
+	rcu_read_unlock();
 }
 
-struct sn_irq_info *sn_irq_alloc(nasid_t local_nasid, int local_widget, int irq,
-				 nasid_t nasid, int slice)
+static void sn_irq_info_free(struct rcu_head *head)
 {
 	struct sn_irq_info *sn_irq_info;
-	int status;
-
-	sn_irq_info = kmalloc(sizeof(*sn_irq_info), GFP_KERNEL);
-	if (sn_irq_info == NULL)
-		return NULL;
-
-	memset(sn_irq_info, 0x0, sizeof(*sn_irq_info));
-
-	status =
-	    sn_intr_alloc(local_nasid, local_widget, __pa(sn_irq_info), irq,
-			  nasid, slice);
-
-	if (status) {
-		kfree(sn_irq_info);
-		return NULL;
-	} else {
-		return sn_irq_info;
-	}
-}
-
-void sn_irq_free(struct sn_irq_info *sn_irq_info)
-{
-	uint64_t bridge = (uint64_t) sn_irq_info->irq_bridge;
-	nasid_t local_nasid = NASID_GET(bridge);
-	int local_widget;
-
-	if (local_nasid & 1)	/* tio check */
-		local_widget = TIO_SWIN_WIDGETNUM(bridge);
-	else
-		local_widget = SWIN_WIDGETNUM(bridge);
-
-	sn_intr_free(local_nasid, local_widget, sn_irq_info);
 
+	sn_irq_info = container_of(head, struct sn_irq_info, rcu);
 	kfree(sn_irq_info);
 }
 
@@ -314,30 +284,54 @@ void sn_irq_fixup(struct pci_dev *pci_dev, struct sn_irq_info *sn_irq_info)
 	int slice = sn_irq_info->irq_slice;
 	int cpu = nasid_slice_to_cpuid(nasid, slice);
 
+	pci_dev_get(pci_dev);
+
 	sn_irq_info->irq_cpuid = cpu;
 	sn_irq_info->irq_pciioinfo = SN_PCIDEV_INFO(pci_dev);
 
 	/* link it into the sn_irq[irq] list */
-	sn_irq_info->irq_next = sn_irq[sn_irq_info->irq_irq];
-	sn_irq[sn_irq_info->irq_irq] = sn_irq_info;
+	spin_lock(&sn_irq_info_lock);
+	list_add_rcu(&sn_irq_info->list, sn_irq_lh[sn_irq_info->irq_irq]);
+	spin_unlock(&sn_irq_info_lock);
 
 	(void)register_intr_pda(sn_irq_info);
 }
 
+void sn_irq_unfixup(struct pci_dev *pci_dev)
+{
+	struct sn_irq_info *sn_irq_info;
+
+	/* Only cleanup IRQ stuff if this device has a host bus context */
+	if (!SN_PCIDEV_BUSSOFT(pci_dev))
+		return;
+
+	sn_irq_info = SN_PCIDEV_INFO(pci_dev)->pdi_sn_irq_info;
+	if (!sn_irq_info || !sn_irq_info->irq_irq)
+		return;
+
+	unregister_intr_pda(sn_irq_info);
+	spin_lock(&sn_irq_info_lock);
+	list_del_rcu(&sn_irq_info->list);
+	spin_unlock(&sn_irq_info_lock);
+	call_rcu(&sn_irq_info->rcu, sn_irq_info_free);
+
+	pci_dev_put(pci_dev);
+}
+
 static void force_interrupt(int irq)
 {
 	struct sn_irq_info *sn_irq_info;
 
 	if (!sn_ioif_inited)
 		return;
-	sn_irq_info = sn_irq[irq];
-	while (sn_irq_info) {
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sn_irq_info, sn_irq_lh[irq], list) {
 		if (IS_PCI_BRIDGE_ASIC(sn_irq_info->irq_bridge_type) &&
-		    (sn_irq_info->irq_bridge != NULL)) {
+		    (sn_irq_info->irq_bridge != NULL))
 			pcibr_force_interrupt(sn_irq_info);
 	}
-		sn_irq_info = sn_irq_info->irq_next;
-	}
+	rcu_read_unlock();
 }
 
 /*
@@ -402,19 +396,41 @@ static void sn_check_intr(int irq, struct sn_irq_info *sn_irq_info)
 
 void sn_lb_int_war_check(void)
 {
+	struct sn_irq_info *sn_irq_info;
 	int i;
 
 	if (!sn_ioif_inited || pda->sn_first_irq == 0)
 		return;
+
+	rcu_read_lock();
 	for (i = pda->sn_first_irq; i <= pda->sn_last_irq; i++) {
-		struct sn_irq_info *sn_irq_info = sn_irq[i];
-		while (sn_irq_info) {
-			/* Only call for PCI bridges that are fully initialized. */
+		list_for_each_entry_rcu(sn_irq_info, sn_irq_lh[i], list) {
+			/*
+			 * Only call for PCI bridges that are fully
+			 * initialized.
+			 */
 			if (IS_PCI_BRIDGE_ASIC(sn_irq_info->irq_bridge_type) &&
-			    (sn_irq_info->irq_bridge != NULL)) {
+			    (sn_irq_info->irq_bridge != NULL))
 				sn_check_intr(i, sn_irq_info);
 		}
-			sn_irq_info = sn_irq_info->irq_next;
 	}
+	rcu_read_unlock();
+}
+
+void sn_irq_lh_init(void)
+{
+	int i;
+
+	sn_irq_lh = kmalloc(sizeof(struct list_head *) * NR_IRQS, GFP_KERNEL);
+	if (!sn_irq_lh)
+		panic("SN PCI INIT: Failed to allocate memory for PCI init\n");
+
+	for (i = 0; i < NR_IRQS; i++) {
+		sn_irq_lh[i] = kmalloc(sizeof(struct list_head), GFP_KERNEL);
+		if (!sn_irq_lh[i])
+			panic("SN PCI INIT: Failed IRQ memory allocation\n");
+
+		INIT_LIST_HEAD(sn_irq_lh[i]);
 	}
+
 }

include/asm-ia64/sn/intr.h

@@ -9,6 +9,8 @@
 #ifndef _ASM_IA64_SN_INTR_H
 #define _ASM_IA64_SN_INTR_H
 
+#include <linux/rcupdate.h>
+
 #define SGI_UART_VECTOR		(0xe9)
 #define SGI_PCIBR_ERROR		(0x33)
 
@@ -33,7 +35,7 @@
 
 // The SN PROM irq struct
 struct sn_irq_info {
-	struct sn_irq_info *irq_next;	/* sharing irq list	     */
+	struct sn_irq_info *irq_next;	/* deprecated DO NOT USE     */
 	short		irq_nasid;	/* Nasid IRQ is assigned to  */
 	int		irq_slice;	/* slice IRQ is assigned to  */
 	int		irq_cpuid;	/* kernel logical cpuid	     */
@@ -47,6 +49,8 @@ struct sn_irq_info {
 	int		irq_cookie;	/* unique cookie 	     */
 	int		irq_flags;	/* flags */
 	int		irq_share_cnt;	/* num devices sharing IRQ   */
+	struct list_head	list;	/* list of sn_irq_info structs */
+	struct rcu_head		rcu;	/* rcu callback list */
 };
 
 extern void sn_send_IPI_phys(int, long, int, int);

include/asm-ia64/sn/pcidev.h

@@ -10,8 +10,6 @@
 
 #include <linux/pci.h>
 
-extern struct sn_irq_info **sn_irq;
-
 #define SN_PCIDEV_INFO(pci_dev) \
         ((struct pcidev_info *)(pci_dev)->sysdata)
 
@@ -50,9 +48,11 @@ struct pcidev_info {
 
 	struct sn_irq_info	*pdi_sn_irq_info;
 	struct sn_pcibus_provider *pdi_provider;	/* sn pci ops */
+	struct pci_dev 		*host_pci_dev;		/* host bus link */
 };
 
 extern void sn_irq_fixup(struct pci_dev *pci_dev,
 			 struct sn_irq_info *sn_irq_info);
 
+extern void sn_irq_lh_init(void);
 #endif				/* _ASM_IA64_SN_PCI_PCIDEV_H */