[PATCH 5/7] xen/events: drop xen_allocate_irqs_dynamic()

[Juergen Gross <jgross@xxxxxxxx>]

Instead of having a common function for allocating a single IRQ or a
consecutive number of IRQs, split up the functionality into the callers
of xen_allocate_irqs_dynamic().

This allows to handle any allocation error in xen_irq_init() gracefully
instead of panicing the system. Let xen_irq_init() return the irq_info
pointer or NULL in case of an allocation error.

Additionally set the IRQ into irq_info already at allocation time, as
otherwise the IRQ would be '0' (which is a valid IRQ number) until
being set.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 drivers/xen/events/events_base.c | 74 +++++++++++++++++++-------------
 1 file changed, 44 insertions(+), 30 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 4ada3b6a4164..58e5549ee1db 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -302,6 +302,13 @@ static void channels_on_cpu_inc(struct irq_info *info)
        info->is_accounted = 1;
 }
 
+static void xen_irq_free_desc(unsigned int irq)
+{
+       /* Legacy IRQ descriptors are managed by the arch. */
+       if (irq >= nr_legacy_irqs())
+               irq_free_desc(irq);
+}
+
 static void delayed_free_irq(struct work_struct *work)
 {
        struct irq_info *info = container_of(to_rcu_work(work), struct irq_info,
@@ -313,9 +320,7 @@ static void delayed_free_irq(struct work_struct *work)
 
        kfree(info);
 
-       /* Legacy IRQ descriptors are managed by the arch. */
-       if (irq >= nr_legacy_irqs())
-               irq_free_desc(irq);
+       xen_irq_free_desc(irq);
 }
 
 /* Constructors for packed IRQ information. */
@@ -330,7 +335,6 @@ static int xen_irq_info_common_setup(struct irq_info *info,
        BUG_ON(info->type != IRQT_UNBOUND && info->type != type);
 
        info->type = type;
-       info->irq = irq;
        info->evtchn = evtchn;
        info->cpu = cpu;
        info->mask_reason = EVT_MASK_REASON_EXPLICIT;
@@ -730,47 +734,45 @@ void xen_irq_lateeoi(unsigned int irq, unsigned int 
eoi_flags)
 }
 EXPORT_SYMBOL_GPL(xen_irq_lateeoi);
 
-static void xen_irq_init(unsigned irq)
+static struct irq_info *xen_irq_init(unsigned int irq)
 {
        struct irq_info *info;
 
        info = kzalloc(sizeof(*info), GFP_KERNEL);
-       if (info == NULL)
-               panic("Unable to allocate metadata for IRQ%d\n", irq);
+       if (info) {
+               info->irq = irq;
+               info->type = IRQT_UNBOUND;
+               info->refcnt = -1;
+               INIT_RCU_WORK(&info->rwork, delayed_free_irq);
 
-       info->type = IRQT_UNBOUND;
-       info->refcnt = -1;
-       INIT_RCU_WORK(&info->rwork, delayed_free_irq);
+               set_info_for_irq(irq, info);
+               /*
+                * Interrupt affinity setting can be immediate. No point
+                * in delaying it until an interrupt is handled.
+                */
+               irq_set_status_flags(irq, IRQ_MOVE_PCNTXT);
 
-       set_info_for_irq(irq, info);
-       /*
-        * Interrupt affinity setting can be immediate. No point
-        * in delaying it until an interrupt is handled.
-        */
-       irq_set_status_flags(irq, IRQ_MOVE_PCNTXT);
+               INIT_LIST_HEAD(&info->eoi_list);
+               list_add_tail(&info->list, &xen_irq_list_head);
+       }
 
-       INIT_LIST_HEAD(&info->eoi_list);
-       list_add_tail(&info->list, &xen_irq_list_head);
+       return info;
 }
 
-static int __must_check xen_allocate_irqs_dynamic(int nvec)
+static inline int __must_check xen_allocate_irq_dynamic(void)
 {
-       int i, irq = irq_alloc_descs(-1, 0, nvec, -1);
+       int irq = irq_alloc_desc_from(0, -1);
 
        if (irq >= 0) {
-               for (i = 0; i < nvec; i++)
-                       xen_irq_init(irq + i);
+               if (!xen_irq_init(irq)) {
+                       xen_irq_free_desc(irq);
+                       irq = -1;
+               }
        }
 
        return irq;
 }
 
-static inline int __must_check xen_allocate_irq_dynamic(void)
-{
-
-       return xen_allocate_irqs_dynamic(1);
-}
-
 static int __must_check xen_allocate_irq_gsi(unsigned gsi)
 {
        int irq;
@@ -790,7 +792,10 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi)
        else
                irq = irq_alloc_desc_at(gsi, -1);
 
-       xen_irq_init(irq);
+       if (!xen_irq_init(irq)) {
+               xen_irq_free_desc(irq);
+               irq = -1;
+       }
 
        return irq;
 }
@@ -960,6 +965,11 @@ static void __unbind_from_irq(unsigned int irq)
        evtchn_port_t evtchn = evtchn_from_irq(irq);
        struct irq_info *info = info_for_irq(irq);
 
+       if (!info) {
+               xen_irq_free_desc(irq);
+               return;
+       }
+
        if (info->refcnt > 0) {
                info->refcnt--;
                if (info->refcnt != 0)
@@ -1097,11 +1107,14 @@ int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, 
struct msi_desc *msidesc,
 
        mutex_lock(&irq_mapping_update_lock);
 
-       irq = xen_allocate_irqs_dynamic(nvec);
+       irq = irq_alloc_descs(-1, 0, nvec, -1);
        if (irq < 0)
                goto out;
 
        for (i = 0; i < nvec; i++) {
+               if (!xen_irq_init(irq + i))
+                       goto error_irq;
+
                irq_set_chip_and_handler_name(irq + i, &xen_pirq_chip, 
handle_edge_irq, name);
 
                ret = xen_irq_info_pirq_setup(irq + i, 0, pirq + i, 0, domid,
@@ -1725,6 +1738,7 @@ void rebind_evtchn_irq(evtchn_port_t evtchn, int irq)
           so there should be a proper type */
        BUG_ON(info->type == IRQT_UNBOUND);
 
+       info->irq = irq;
        (void)xen_irq_info_evtchn_setup(irq, evtchn, NULL);
 
        mutex_unlock(&irq_mapping_update_lock);
-- 
2.35.3