1 files changed, 89 insertions, 65 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 2d75c94ae87d..7a4104cb95cb 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -34,21 +34,19 @@ static void update_pages_handler(struct work_struct *work);
  */
 int ring_buffer_print_entry_header(struct trace_seq *s)
 {
-        int ret;
-
-        ret = trace_seq_puts(s, "# compressed entry header\n");
-        ret = trace_seq_puts(s, "\ttype_len    :    5 bits\n");
-        ret = trace_seq_puts(s, "\ttime_delta  :   27 bits\n");
-        ret = trace_seq_puts(s, "\tarray       :   32 bits\n");
-        ret = trace_seq_putc(s, '\n');
-        ret = trace_seq_printf(s, "\tpadding     : type == %d\n",
-                               RINGBUF_TYPE_PADDING);
-        ret = trace_seq_printf(s, "\ttime_extend : type == %d\n",
-                               RINGBUF_TYPE_TIME_EXTEND);
-        ret = trace_seq_printf(s, "\tdata max type_len  == %d\n",
-                               RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
+        trace_seq_puts(s, "# compressed entry header\n");
+        trace_seq_puts(s, "\ttype_len    :    5 bits\n");
+        trace_seq_puts(s, "\ttime_delta  :   27 bits\n");
+        trace_seq_puts(s, "\tarray       :   32 bits\n");
+        trace_seq_putc(s, '\n');
+        trace_seq_printf(s, "\tpadding     : type == %d\n",
+                         RINGBUF_TYPE_PADDING);
+        trace_seq_printf(s, "\ttime_extend : type == %d\n",
+                         RINGBUF_TYPE_TIME_EXTEND);
+        trace_seq_printf(s, "\tdata max type_len  == %d\n",
+                         RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
 
-        return ret;
+        return !trace_seq_has_overflowed(s);
 }
 
 /*
@@ -419,32 +417,31 @@ static inline int test_time_stamp(u64 delta)
 int ring_buffer_print_page_header(struct trace_seq *s)
 {
         struct buffer_data_page field;
-        int ret;
 
-        ret = trace_seq_printf(s, "\tfield: u64 timestamp;\t"
-                               "offset:0;\tsize:%u;\tsigned:%u;\n",
-                               (unsigned int)sizeof(field.time_stamp),
-                               (unsigned int)is_signed_type(u64));
-
-        ret = trace_seq_printf(s, "\tfield: local_t commit;\t"
-                               "offset:%u;\tsize:%u;\tsigned:%u;\n",
-                               (unsigned int)offsetof(typeof(field), commit),
-                               (unsigned int)sizeof(field.commit),
-                               (unsigned int)is_signed_type(long));
-
-        ret = trace_seq_printf(s, "\tfield: int overwrite;\t"
-                               "offset:%u;\tsize:%u;\tsigned:%u;\n",
-                               (unsigned int)offsetof(typeof(field), commit),
-                               1,
-                               (unsigned int)is_signed_type(long));
-
-        ret = trace_seq_printf(s, "\tfield: char data;\t"
-                               "offset:%u;\tsize:%u;\tsigned:%u;\n",
-                               (unsigned int)offsetof(typeof(field), data),
-                               (unsigned int)BUF_PAGE_SIZE,
-                               (unsigned int)is_signed_type(char));
+        trace_seq_printf(s, "\tfield: u64 timestamp;\t"
+                         "offset:0;\tsize:%u;\tsigned:%u;\n",
+                         (unsigned int)sizeof(field.time_stamp),
+                         (unsigned int)is_signed_type(u64));
 
-        return ret;
+        trace_seq_printf(s, "\tfield: local_t commit;\t"
+                         "offset:%u;\tsize:%u;\tsigned:%u;\n",
+                         (unsigned int)offsetof(typeof(field), commit),
+                         (unsigned int)sizeof(field.commit),
+                         (unsigned int)is_signed_type(long));
+
+        trace_seq_printf(s, "\tfield: int overwrite;\t"
+                         "offset:%u;\tsize:%u;\tsigned:%u;\n",
+                         (unsigned int)offsetof(typeof(field), commit),
+                         1,
+                         (unsigned int)is_signed_type(long));
+
+        trace_seq_printf(s, "\tfield: char data;\t"
+                         "offset:%u;\tsize:%u;\tsigned:%u;\n",
+                         (unsigned int)offsetof(typeof(field), data),
+                         (unsigned int)BUF_PAGE_SIZE,
+                         (unsigned int)is_signed_type(char));
+
+        return !trace_seq_has_overflowed(s);
 }
 
 struct rb_irq_work {
@@ -538,16 +535,18 @@ static void rb_wake_up_waiters(struct irq_work *work)
  * ring_buffer_wait - wait for input to the ring buffer
  * @buffer: buffer to wait on
  * @cpu: the cpu buffer to wait on
+ * @full: wait until a full page is available, if @cpu != RING_BUFFER_ALL_CPUS
  *
  * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon
  * as data is added to any of the @buffer's cpu buffers. Otherwise
  * it will wait for data to be added to a specific cpu buffer.
  */
-int ring_buffer_wait(struct ring_buffer *buffer, int cpu)
+int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full)
 {
-        struct ring_buffer_per_cpu *cpu_buffer;
+        struct ring_buffer_per_cpu *uninitialized_var(cpu_buffer);
         DEFINE_WAIT(wait);
         struct rb_irq_work *work;
+        int ret = 0;
 
         /*
          * Depending on what the caller is waiting for, either any
@@ -564,36 +563,61 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu)
         }
 
 
-        prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE);
+        while (true) {
+                prepare_to_wait(&work->waiters, &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.
-         */
-        work->waiters_pending = true;
+                /*
+                 * 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.
+                 */
+                work->waiters_pending = true;
+
+                if (signal_pending(current)) {
+                        ret = -EINTR;
+                        break;
+                }
+
+                if (cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer))
+                        break;
+
+                if (cpu != RING_BUFFER_ALL_CPUS &&
+                    !ring_buffer_empty_cpu(buffer, cpu)) {
+                        unsigned long flags;
+                        bool pagebusy;
+
+                        if (!full)
+                                break;
+
+                        raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+                        pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;
+                        raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+
+                        if (!pagebusy)
+                                break;
+                }
 
-        if ((cpu == RING_BUFFER_ALL_CPUS && ring_buffer_empty(buffer)) ||
-            (cpu != RING_BUFFER_ALL_CPUS && ring_buffer_empty_cpu(buffer, cpu)))
                 schedule();
+        }
 
         finish_wait(&work->waiters, &wait);
-        return 0;
+
+        return ret;
 }
 
 /**