genirq: Do not copy affinity before set

While rumaging through arch code I found that there are a few
workarounds which deal with the fact that the initial affinity setting
from request_irq() copies the mask into irq_data->affinity before the
chip code is called. In the normal path we unconditionally copy the
mask when the chip code returns 0.

Copy after the code is called and add a return code
IRQ_SET_MASK_OK_NOCOPY for the chip functions, which prevents the
copy. That way we see the real mask when the chip function decided to
truncate it further as some arches do. IRQ_SET_MASK_OK is 0, which is
the current behaviour.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 34 insertions, 13 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index ade65bfb466d..dc95d53df510 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -148,9 +148,12 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
 
         if (irq_can_move_pcntxt(desc)) {
                 ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
-                if (!ret) {
+                switch (ret) {
+                case IRQ_SET_MASK_OK:
                         cpumask_copy(desc->irq_data.affinity, mask);
+                case IRQ_SET_MASK_OK_NOCOPY:
                         irq_set_thread_affinity(desc);
+                        ret = 0;
                 }
         } else {
                 desc->status |= IRQ_MOVE_PENDING;
@@ -254,9 +257,12 @@ EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
 /*
  * Generic version of the affinity autoselector.
  */
-static int setup_affinity(unsigned int irq, struct irq_desc *desc)
+static int
+setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 {
+        struct irq_chip *chip = get_irq_desc_chip(desc);
         struct cpumask *set = irq_default_affinity;
+        int ret;
 
         /* Excludes PER_CPU and NO_BALANCE interrupts */
         if (!irq_can_set_affinity(irq))
@@ -273,13 +279,20 @@ static int setup_affinity(unsigned int irq, struct irq_desc *desc)
                 else
                         desc->status &= ~IRQ_AFFINITY_SET;
         }
-        cpumask_and(desc->irq_data.affinity, cpu_online_mask, set);
-        desc->irq_data.chip->irq_set_affinity(&desc->irq_data, desc->irq_data.affinity, false);
 
+        cpumask_and(mask, cpu_online_mask, set);
+        ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
+        switch (ret) {
+        case IRQ_SET_MASK_OK:
+                cpumask_copy(desc->irq_data.affinity, mask);
+        case IRQ_SET_MASK_OK_NOCOPY:
+                irq_set_thread_affinity(desc);
+        }
         return 0;
 }
 #else
-static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
+static inline int
+setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
 {
         return irq_select_affinity(irq);
 }
@@ -288,23 +301,23 @@ static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
 /*
  * Called when affinity is set via /proc/irq
  */
-int irq_select_affinity_usr(unsigned int irq)
+int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
 {
         struct irq_desc *desc = irq_to_desc(irq);
         unsigned long flags;
         int ret;
 
         raw_spin_lock_irqsave(&desc->lock, flags);
-        ret = setup_affinity(irq, desc);
+        ret = setup_affinity(irq, desc, mask);
         if (!ret)
                 irq_set_thread_affinity(desc);
         raw_spin_unlock_irqrestore(&desc->lock, flags);
-
         return ret;
 }
 
 #else
-static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
+static inline int
+setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 {
         return 0;
 }
@@ -765,8 +778,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
         struct irqaction *old, **old_ptr;
         const char *old_name = NULL;
         unsigned long flags;
-        int nested, shared = 0;
-        int ret;
+        int ret, nested, shared = 0;
+        cpumask_var_t mask;
 
         if (!desc)
                 return -EINVAL;
@@ -831,6 +844,11 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                 new->thread = t;
         }
 
+        if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
+                ret = -ENOMEM;
+                goto out_thread;
+        }
+
         /*
          * The following block of code has to be executed atomically
          */
@@ -876,7 +894,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                                         new->flags & IRQF_TRIGGER_MASK);
 
                         if (ret)
-                                goto out_thread;
+                                goto out_mask;
                 } else
                         compat_irq_chip_set_default_handler(desc);
 #if defined(CONFIG_IRQ_PER_CPU)
@@ -903,7 +921,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                         desc->status |= IRQ_NO_BALANCING;
 
                 /* Set default affinity mask once everything is setup */
-                setup_affinity(irq, desc);
+                setup_affinity(irq, desc, mask);
 
         } else if ((new->flags & IRQF_TRIGGER_MASK)
                         && (new->flags & IRQF_TRIGGER_MASK)
@@ -956,6 +974,9 @@ mismatch:
 #endif
         ret = -EBUSY;
 
+out_mask:
+        free_cpumask_var(mask);
+
 out_thread:
         raw_spin_unlock_irqrestore(&desc->lock, flags);
         if (new->thread) {