Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome...

[firefly-linux-kernel-4.4.55.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ff7027199a9a32ea9281bca4e2049ebbb549dd38..afb04b9b818a473f8b38e0aa94ee12ad84c44d1a 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1689,22 +1689,14 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
                        if (!cpu_buffer->nr_pages_to_update)
                                continue;
 
-                       /* The update must run on the CPU that is being updated. */
-                       preempt_disable();
-                       if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+                       /* Can't run something on an offline CPU. */
+                       if (!cpu_online(cpu)) {
                                rb_update_pages(cpu_buffer);
                                cpu_buffer->nr_pages_to_update = 0;
                        } else {
-                               /*
-                                * Can not disable preemption for schedule_work_on()
-                                * on PREEMPT_RT.
-                                */
-                               preempt_enable();
                                schedule_work_on(cpu,
                                                &cpu_buffer->update_pages_work);
-                               preempt_disable();
                        }
-                       preempt_enable();
                }
 
                /* wait for all the updates to complete */
@@ -1742,22 +1734,14 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
 
                get_online_cpus();
 
-               preempt_disable();
-               /* The update must run on the CPU that is being updated. */
-               if (cpu_id == smp_processor_id() || !cpu_online(cpu_id))
+               /* Can't run something on an offline CPU. */
+               if (!cpu_online(cpu_id))
                        rb_update_pages(cpu_buffer);
                else {
-                       /*
-                        * Can not disable preemption for schedule_work_on()
-                        * on PREEMPT_RT.
-                        */
-                       preempt_enable();
                        schedule_work_on(cpu_id,
                                         &cpu_buffer->update_pages_work);
                        wait_for_completion(&cpu_buffer->update_done);
-                       preempt_disable();
                }
-               preempt_enable();
 
                cpu_buffer->nr_pages_to_update = 0;
                put_online_cpus();
@@ -1984,7 +1968,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta)
 
 /**
  * rb_update_event - update event type and data
- * @event: the even to update
+ * @event: the event to update
  * @type: the type of event
  * @length: the size of the event field in the ring buffer
  *
@@ -3357,21 +3341,16 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
        struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
 
        /* Iterator usage is expected to have record disabled */
-       if (list_empty(&cpu_buffer->reader_page->list)) {
-               iter->head_page = rb_set_head_page(cpu_buffer);
-               if (unlikely(!iter->head_page))
-                       return;
-               iter->head = iter->head_page->read;
-       } else {
-               iter->head_page = cpu_buffer->reader_page;
-               iter->head = cpu_buffer->reader_page->read;
-       }
+       iter->head_page = cpu_buffer->reader_page;
+       iter->head = cpu_buffer->reader_page->read;
+
+       iter->cache_reader_page = iter->head_page;
+       iter->cache_read = iter->head;
+
        if (iter->head)
                iter->read_stamp = cpu_buffer->read_stamp;
        else
                iter->read_stamp = iter->head_page->page->time_stamp;
-       iter->cache_reader_page = cpu_buffer->reader_page;
-       iter->cache_read = cpu_buffer->read;
 }
 
 /**
@@ -3764,18 +3743,20 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
                return NULL;
 
        /*
-        * We repeat when a time extend is encountered.
-        * Since the time extend is always attached to a data event,
-        * we should never loop more than once.
-        * (We never hit the following condition more than twice).
+        * We repeat when a time extend is encountered or we hit
+        * the end of the page. Since the time extend is always attached
+        * to a data event, we should never loop more than three times.
+        * Once for going to next page, once on time extend, and
+        * finally once to get the event.
+        * (We never hit the following condition more than thrice).
         */
-       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2))
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3))
                return NULL;
 
        if (rb_per_cpu_empty(cpu_buffer))
                return NULL;
 
-       if (iter->head >= local_read(&iter->head_page->page->commit)) {
+       if (iter->head >= rb_page_size(iter->head_page)) {
                rb_inc_iter(iter);
                goto again;
        }