lib: cpu_rmap: Add irq_cpu_rmap_remove to complement irq_cpu_rmap_add

Add a function to complement irq_cpu_rmap_add(). It removes the irq from
the reverse mapping by setting the notifier to NULL. The function calls
irq_set_affinity_notifier() with NULL at the notify argument which then
cancel any pending notifier work and decrement reference on the
notifier. When ref count reaches zero, the glue pointer is kfree and the
rmap entry is set to NULL serving both to avoid second attempt to
release it and also making the rmap entry available for subsequent
mapping.

It should be noted the drivers usually creates the reverse mapping at
initialization time and remove it at unload time so we do not expect
failures in allocating rmap due to kref holding the glue entry.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

diff --git a/include/linux/cpu_rmap.h b/include/linux/cpu_rmap.h
index 0ec745e6cd360865eca91ce06c08d406452fef3c..cae324d10965a0bcc0ca59b4fba6eaee8f9f9a40 100644 (file)
--- a/include/linux/cpu_rmap.h
+++ b/include/linux/cpu_rmap.h
@@ -60,6 +60,7 @@ static inline struct cpu_rmap *alloc_irq_cpu_rmap(unsigned int size)
 }
 extern void free_irq_cpu_rmap(struct cpu_rmap *rmap);
 
+int irq_cpu_rmap_remove(struct cpu_rmap *rmap, int irq);
 extern int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq);
 
 #endif /* __LINUX_CPU_RMAP_H */

diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index 5d4bf7a8b926b17cddad10cf6ffc8c3aa02cdde2..73c1636b927ba823db791443f32c02341bf94295 100644 (file)
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -285,6 +285,17 @@ static void irq_cpu_rmap_release(struct kref *ref)
        kfree(glue);
 }
 
+/**
+ * irq_cpu_rmap_remove - remove an IRQ from a CPU affinity reverse-map
+ * @rmap: The reverse-map
+ * @irq: The IRQ number
+ */
+int irq_cpu_rmap_remove(struct cpu_rmap *rmap, int irq)
+{
+       return irq_set_affinity_notifier(irq, NULL);
+}
+EXPORT_SYMBOL(irq_cpu_rmap_remove);
+
 /**
  * irq_cpu_rmap_add - add an IRQ to a CPU affinity reverse-map
  * @rmap: The reverse-map