These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / kernel / events / ring_buffer.c

diff --git a/kernel/kernel/events/ring_buffer.c b/kernel/kernel/events/ring_buffer.c
index a7604c8..adfdc05 100644 (file)
--- a/kernel/kernel/events/ring_buffer.c
+++ b/kernel/kernel/events/ring_buffer.c
@@ -3,7 +3,7 @@
  *
  *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
  *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
- *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
  *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
  *
  * For licensing details see kernel-base/COPYING
@@ -141,7 +141,7 @@ int perf_output_begin(struct perf_output_handle *handle,
        perf_output_get_handle(handle);
 
        do {
-               tail = ACCESS_ONCE(rb->user_page->data_tail);
+               tail = READ_ONCE(rb->user_page->data_tail);
                offset = head = local_read(&rb->head);
                if (!rb->overwrite &&
                    unlikely(CIRC_SPACE(head, tail, perf_data_size(rb)) < size))
@@ -221,6 +221,8 @@ void perf_output_end(struct perf_output_handle *handle)
        rcu_read_unlock();
 }
 
+static void rb_irq_work(struct irq_work *work);
+
 static void
 ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
 {
@@ -241,6 +243,16 @@ ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
 
        INIT_LIST_HEAD(&rb->event_list);
        spin_lock_init(&rb->event_lock);
+       init_irq_work(&rb->irq_work, rb_irq_work);
+}
+
+static void ring_buffer_put_async(struct ring_buffer *rb)
+{
+       if (!atomic_dec_and_test(&rb->refcount))
+               return;
+
+       rb->rcu_head.next = (void *)rb;
+       irq_work_queue(&rb->irq_work);
 }
 
 /*
@@ -319,7 +331,7 @@ err_put:
        rb_free_aux(rb);
 
 err:
-       ring_buffer_put(rb);
+       ring_buffer_put_async(rb);
        handle->event = NULL;
 
        return NULL;
@@ -370,7 +382,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
 
        local_set(&rb->aux_nest, 0);
        rb_free_aux(rb);
-       ring_buffer_put(rb);
+       ring_buffer_put_async(rb);
 }
 
 /*
@@ -425,7 +437,10 @@ static struct page *rb_alloc_aux_page(int node, int order)
 
        if (page && order) {
                /*
-                * Communicate the allocation size to the driver
+                * Communicate the allocation size to the driver:
+                * if we managed to secure a high-order allocation,
+                * set its first page's private to this order;
+                * !PagePrivate(page) means it's just a normal page.
                 */
                split_page(page, order);
                SetPagePrivate(page);
@@ -559,7 +574,18 @@ static void __rb_free_aux(struct ring_buffer *rb)
 void rb_free_aux(struct ring_buffer *rb)
 {
        if (atomic_dec_and_test(&rb->aux_refcount))
+               irq_work_queue(&rb->irq_work);
+}
+
+static void rb_irq_work(struct irq_work *work)
+{
+       struct ring_buffer *rb = container_of(work, struct ring_buffer, irq_work);
+
+       if (!atomic_read(&rb->aux_refcount))
                __rb_free_aux(rb);
+
+       if (rb->rcu_head.next == (void *)rb)
+               call_rcu(&rb->rcu_head, rb_free_rcu);
 }
 
 #ifndef CONFIG_PERF_USE_VMALLOC