1 files changed, 12 insertions, 71 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3ec146c96df4..b5b25b6575a9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -19,7 +19,6 @@
 #include <linux/seq_file.h>
 #include <linux/notifier.h>
 #include <linux/irqflags.h>
-#include <linux/irq_work.h>
 #include <linux/debugfs.h>
 #include <linux/pagemap.h>
 #include <linux/hardirq.h>
@@ -87,14 +86,6 @@ static int dummy_set_flag(u32 old_flags, u32 bit, int set)
 static DEFINE_PER_CPU(bool, trace_cmdline_save);
 
 /*
- * When a reader is waiting for data, then this variable is
- * set to true.
- */
-static bool trace_wakeup_needed;
-
-static struct irq_work trace_work_wakeup;
-
-/*
  * Kill all tracing for good (never come back).
  * It is initialized to 1 but will turn to zero if the initialization
  * of the tracer is successful. But that is the only place that sets
@@ -334,9 +325,6 @@ static inline void trace_access_lock_init(void)
 
 #endif
 
-/* trace_wait is a waitqueue for tasks blocked on trace_poll */
-static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
-
 /* trace_flags holds trace_options default values */
 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
         TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
@@ -344,19 +332,6 @@ unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
         TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS;
 
 /**
- * trace_wake_up - wake up tasks waiting for trace input
- *
- * Schedules a delayed work to wake up any task that is blocked on the
- * trace_wait queue. These is used with trace_poll for tasks polling the
- * trace.
- */
-static void trace_wake_up(struct irq_work *work)
-{
-        wake_up_all(&trace_wait);
-
-}
-
-/**
  * tracing_on - enable tracing buffers
  *
  * This function enables tracing buffers that may have been
@@ -763,36 +738,11 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
 static void default_wait_pipe(struct trace_iterator *iter)
 {
-        DEFINE_WAIT(wait);
-
-        prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
-
-        /*
-         * The events can happen in critical sections where
-         * checking a work queue can cause deadlocks.
-         * After adding a task to the queue, this flag is set
-         * only to notify events to try to wake up the queue
-         * using irq_work.
-         *
-         * We don't clear it even if the buffer is no longer
-         * empty. The flag only causes the next event to run
-         * irq_work to do the work queue wake up. The worse
-         * that can happen if we race with !trace_empty() is that
-         * an event will cause an irq_work to try to wake up
-         * an empty queue.
-         *
-         * There's no reason to protect this flag either, as
-         * the work queue and irq_work logic will do the necessary
-         * synchronization for the wake ups. The only thing
-         * that is necessary is that the wake up happens after
-         * a task has been queued. It's OK for spurious wake ups.
-         */
-        trace_wakeup_needed = true;
-
-        if (trace_empty(iter))
-                schedule();
+        /* Iterators are static, they should be filled or empty */
+        if (trace_buffer_iter(iter, iter->cpu_file))
+                return;
 
-        finish_wait(&trace_wait, &wait);
+        ring_buffer_wait(iter->tr->buffer, iter->cpu_file);
 }
 
 /**
@@ -1262,11 +1212,6 @@ void
 __buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
 {
         __this_cpu_write(trace_cmdline_save, true);
-        if (trace_wakeup_needed) {
-                trace_wakeup_needed = false;
-                /* irq_work_queue() supplies it's own memory barriers */
-                irq_work_queue(&trace_work_wakeup);
-        }
         ring_buffer_unlock_commit(buffer, event);
 }
 
@@ -3557,21 +3502,18 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
 static unsigned int
 trace_poll(struct trace_iterator *iter, struct file *filp, poll_table *poll_table)
 {
-        if (trace_flags & TRACE_ITER_BLOCK) {
+        /* Iterators are static, they should be filled or empty */
+        if (trace_buffer_iter(iter, iter->cpu_file))
+                return POLLIN | POLLRDNORM;
+
+        if (trace_flags & TRACE_ITER_BLOCK)
                 /*
                  * Always select as readable when in blocking mode
                  */
                 return POLLIN | POLLRDNORM;
-        } else {
-                if (!trace_empty(iter))
-                        return POLLIN | POLLRDNORM;
-                trace_wakeup_needed = true;
-                poll_wait(filp, &trace_wait, poll_table);
-                if (!trace_empty(iter))
-                        return POLLIN | POLLRDNORM;
-
-                return 0;
-        }
+        else
+                return ring_buffer_poll_wait(iter->tr->buffer, iter->cpu_file,
+                                             filp, poll_table);
 }
 
 static unsigned int
@@ -5701,7 +5643,6 @@ __init static int tracer_alloc_buffers(void)
 #endif
 
         trace_init_cmdlines();
-        init_irq_work(&trace_work_wakeup, trace_wake_up);
 
         register_tracer(&nop_trace);