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[Xen-devel] [PATCH v3 18/18] xen/arm: IRQ: Handle multiple action per IRQ



On ARM, it may happen (eg ARM SMMU) to setup multiple handler for the same
interrupt.

To be able to use multiple action, the driver has to explicitly call
{setup,request}_irq with IRQF_SHARED as 2nd parameter.

The behavior stays the same on x86, e.g only one action is handled.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>

---
    Changes in v3:
        - Drop {setup,request}_irq_flags, the current function has been
        extended on an earlier patch.
        - Rename IRQ_SHARED into IRQF_SHARED

    Changes in v2:
        - Explain design choice
        - Introduce CONFIG_IRQ_HAS_MULTIPLE_ACTION
        - Use list instead of custom pointer
        - release_irq should not shutdown the IRQ at the beginning
        - Add IRQ_SHARED flags
        - Introduce request_irq_flags and setup_irq_flags
        - Fix compilation on x86. Some code are creating the irqaction
        via = { ... } so the "next" field should be moved
        toward the end
---
 xen/arch/arm/irq.c           |   83 +++++++++++++++++++++++++++++++-----------
 xen/common/irq.c             |    3 ++
 xen/include/asm-arm/config.h |    2 +
 xen/include/xen/irq.h        |    8 ++++
 4 files changed, 74 insertions(+), 22 deletions(-)

diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 18217e8..31edfc8 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -68,7 +68,6 @@ static int __init init_irq_data(void)
         struct irq_desc *desc = irq_to_desc(irq);
         init_one_irq_desc(desc);
         desc->irq = irq;
-        desc->action  = NULL;
     }
 
     return 0;
@@ -82,7 +81,6 @@ static int __cpuinit init_local_irq_data(void)
         struct irq_desc *desc = irq_to_desc(irq);
         init_one_irq_desc(desc);
         desc->irq = irq;
-        desc->action  = NULL;
 
         /* PPIs are include in local_irqs, we have to copy the IRQ type from
          * CPU0 otherwise we may miss the type if the IRQ type has been
@@ -107,11 +105,15 @@ void __cpuinit init_secondary_IRQ(void)
 
 static inline struct domain *irq_get_domain(struct irq_desc *desc)
 {
+    struct irqaction *action;
+
     ASSERT(spin_is_locked(&desc->lock));
     ASSERT(desc->status & IRQ_GUEST);
-    ASSERT(desc->action != NULL);
+    ASSERT(!list_empty(&desc->action));
+
+    action = list_entry(desc->action.next, struct irqaction, next);
 
-    return desc->action->dev_id;
+    return action->dev_id;
 }
 
 int request_irq(unsigned int irq, unsigned int irqflags,
@@ -152,7 +154,6 @@ int request_irq(unsigned int irq, unsigned int irqflags,
 void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq)
 {
     struct irq_desc *desc = irq_to_desc(irq);
-    struct irqaction *action = desc->action;
 
     /* TODO: perfc_incr(irqs); */
 
@@ -163,7 +164,7 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, 
int is_fiq)
     spin_lock(&desc->lock);
     desc->handler->ack(desc);
 
-    if ( action == NULL )
+    if ( list_empty(&desc->action) )
     {
         printk("Unknown %s %#3.3x\n",
                is_fiq ? "FIQ" : "IRQ", irq);
@@ -195,12 +196,14 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, 
int is_fiq)
 
     desc->status |= IRQ_INPROGRESS;
 
-    action = desc->action;
     while ( desc->status & IRQ_PENDING )
     {
+        struct irqaction *action, *next;
+
         desc->status &= ~IRQ_PENDING;
         spin_unlock_irq(&desc->lock);
-        action->handler(irq, action->dev_id, regs);
+        list_for_each_entry_safe(action, next, &desc->action, next)
+            action->handler(irq, action->dev_id, regs);
         spin_lock_irq(&desc->lock);
     }
 
@@ -217,33 +220,69 @@ void release_irq(unsigned int irq, const void *dev_id)
 {
     struct irq_desc *desc;
     unsigned long flags;
-   struct irqaction *action;
+    struct irqaction *action;
+    bool_t found = 0;
 
     desc = irq_to_desc(irq);
 
     spin_lock_irqsave(&desc->lock,flags);
 
-    desc->handler->shutdown(desc);
+    list_for_each_entry(action, &desc->action, next)
+    {
+        if ( action->dev_id == dev_id )
+        {
+            found  = 1;
+            break;
+         }
+    }
+
+    if ( !found )
+    {
+        printk(XENLOG_WARNING "Trying to free already-free IRQ %u\n", irq);
+        return;
+    }
 
-    action = desc->action;
-    desc->action  = NULL;
-    desc->status &= ~IRQ_GUEST;
+    /* Found it - remove it from the action list */
+    list_del_init(&action->next);
+
+    /* If this was the last action, shut down the IRQ */
+    if ( list_empty(&desc->action) )
+    {
+        desc->handler->shutdown(desc);
+        desc->status &= ~IRQ_GUEST;
+    }
 
     spin_unlock_irqrestore(&desc->lock,flags);
 
     /* Wait to make sure it's not being used on another CPU */
     do { smp_mb(); } while ( desc->status & IRQ_INPROGRESS );
 
-    if ( action && action->free_on_release )
+    if ( action->free_on_release )
         xfree(action);
 }
 
-static int __setup_irq(struct irq_desc *desc, struct irqaction *new)
+static int __setup_irq(struct irq_desc *desc, unsigned int irqflags,
+                       struct irqaction *new)
 {
-    if ( desc->action != NULL )
-        return -EBUSY;
+    bool_t shared = !!(irqflags & IRQF_SHARED);
+
+    ASSERT(new != NULL);
+
+    /* Sanity checks:
+     *  - if the IRQ is marked as shared
+     *  - dev_id is not NULL when IRQF_SHARED is set
+     */
+    if ( !list_empty(&desc->action) &&
+         (!(desc->status & IRQF_SHARED) || !shared) )
+        return -EINVAL;
+    if ( shared && new->dev_id == NULL )
+        return -EINVAL;
+
+    if ( shared )
+        desc->status |= IRQF_SHARED;
 
-    desc->action  = new;
+    INIT_LIST_HEAD(&new->next);
+    list_add_tail(&new->next, &desc->action);
     dsb(sy);
 
     return 0;
@@ -270,9 +309,9 @@ int setup_irq(unsigned int irq, unsigned int irqflags, 
struct irqaction *new)
         return -EBUSY;
     }
 
-    disabled = (desc->action == NULL);
+    disabled = list_empty(&desc->action);
 
-    rc = __setup_irq(desc, new);
+    rc = __setup_irq(desc, irqflags, new);
     if ( rc )
         goto err;
 
@@ -320,7 +359,7 @@ int route_dt_irq_to_guest(struct domain *d, const struct 
dt_irq *irq,
      *  - Otherwise -> For now, don't allow the IRQ to be shared between
      *  Xen and domains.
      */
-    if ( desc->action != NULL )
+    if ( !list_empty(&desc->action) )
     {
         struct domain *ad = irq_get_domain(desc);
 
@@ -337,7 +376,7 @@ int route_dt_irq_to_guest(struct domain *d, const struct 
dt_irq *irq,
         goto out;
     }
 
-    retval = __setup_irq(desc, action);
+    retval = __setup_irq(desc, 0, action);
     if ( retval )
     {
         xfree(action);
diff --git a/xen/common/irq.c b/xen/common/irq.c
index 3e55dfa..688e48a 100644
--- a/xen/common/irq.c
+++ b/xen/common/irq.c
@@ -17,6 +17,9 @@ int init_one_irq_desc(struct irq_desc *desc)
     spin_lock_init(&desc->lock);
     cpumask_setall(desc->affinity);
     INIT_LIST_HEAD(&desc->rl_link);
+#ifdef CONFIG_IRQ_HAS_MULTIPLE_ACTION
+    INIT_LIST_HEAD(&desc->action);
+#endif
 
     err = arch_init_one_irq_desc(desc);
     if ( err )
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index 5b7b1a8..079e8b9 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -37,6 +37,8 @@
 
 #define CONFIG_VIDEO 1
 
+#define CONFIG_IRQ_HAS_MULTIPLE_ACTION 1
+
 #define OPT_CONSOLE_STR "dtuart"
 
 #ifdef MAX_PHYS_CPUS
diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index f9a18d8..c42b022 100644
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -14,6 +14,9 @@ struct irqaction {
     const char *name;
     void *dev_id;
     bool_t free_on_release;
+#ifdef CONFIG_IRQ_HAS_MULTIPLE_ACTION
+    struct list_head next;
+#endif
 };
 
 /*
@@ -27,6 +30,7 @@ struct irqaction {
 #define IRQ_MOVE_PENDING  (1u<<5) /* IRQ is migrating to another CPUs */
 #define IRQ_PER_CPU       (1u<<6) /* IRQ is per CPU */
 #define IRQ_GUEST_EOI_PENDING (1u<<7) /* IRQ was disabled, pending a guest EOI 
*/
+#define IRQF_SHARED       (1<<8)  /* IRQ is shared */
 
 /* Special IRQ numbers. */
 #define AUTO_ASSIGN_IRQ         (-1)
@@ -68,7 +72,11 @@ typedef struct irq_desc {
     unsigned int status;        /* IRQ status */
     hw_irq_controller *handler;
     struct msi_desc   *msi_desc;
+#ifdef CONFIG_IRQ_HAS_MULTIPLE_ACTION
+    struct list_head action;    /* IRQ action list */
+#else
     struct irqaction *action;   /* IRQ action list */
+#endif
     int irq;
     spinlock_t lock;
     struct arch_irq_desc arch;
-- 
1.7.10.4


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