[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>

4 files changed, 162 insertions, 137 deletions

diff --git a/arch/ia64/sn/kernel/io_init.c b/arch/ia64/sn/kernel/io_init.c
index 783eb4323847..2f03e3f52b63 100644
--- a/arch/ia64/sn/kernel/io_init.c
+++ b/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(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
diff --git a/arch/ia64/sn/kernel/irq.c b/arch/ia64/sn/kernel/irq.c
index 0f4e8138658f..e6f7551edfda 100644
--- a/arch/ia64/sn/kernel/irq.c
+++ b/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,
@@ -101,7 +103,7 @@ static void sn_end_irq(unsigned int irq)
                 nasid = get_nasid();
                 event_occurred = HUB_L((uint64_t *) GLOBAL_MMR_ADDR
                                        (nasid, SH_EVENT_OCCURRED));
-                /* If the UART bit is set here, we may have received an 
+                /* If the UART bit is set here, we may have received an
                  * interrupt from the UART that the driver missed.  To
                  * make sure, we IPI ourselves to force us to look again.
                  */
@@ -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));
+
+                bridge = (uint64_t) new_irq_info->irq_bridge;
+                if (!bridge) {
+                        kfree(new_irq_info);
+                        break; /* irq is not a device interrupt */
+                }
 
-                if (!bridge)
-                        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);
-
-                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);
-                        }
+                                       __pa(new_irq_info), irq,
+                                       cpuid_to_nasid(cpuid),
+                                       cpuid_to_slice(cpuid));
+
+                /* 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);
+                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]);
+        }
+
 }
diff --git a/include/asm-ia64/sn/intr.h b/include/asm-ia64/sn/intr.h
index e51471fb0867..e190dd4213d5 100644
--- a/include/asm-ia64/sn/intr.h
+++ b/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);
diff --git a/include/asm-ia64/sn/pcidev.h b/include/asm-ia64/sn/pcidev.h
index ed4031d80811..42aea21ee187 100644
--- a/include/asm-ia64/sn/pcidev.h
+++ b/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 */