return ret;
}
-/**
- * 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 the percentage of pages are 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 trace_buffer *buffer, int cpu, int full)
+static inline bool
+rb_wait_cond(struct rb_irq_work *rbwork, struct trace_buffer *buffer,
+ int cpu, int full, ring_buffer_cond_fn cond, void *data)
{
- struct ring_buffer_per_cpu *cpu_buffer;
- DEFINE_WAIT(wait);
- struct rb_irq_work *work;
- int ret = 0;
-
- /*
- * Depending on what the caller is waiting for, either any
- * data in any cpu buffer, or a specific buffer, put the
- * caller on the appropriate wait queue.
- */
- if (cpu == RING_BUFFER_ALL_CPUS) {
- work = &buffer->irq_work;
- /* Full only makes sense on per cpu reads */
- full = 0;
- } else {
- if (!cpumask_test_cpu(cpu, buffer->cpumask))
- return -ENODEV;
- cpu_buffer = buffer->buffers[cpu];
- work = &cpu_buffer->irq_work;
- }
+ if (rb_watermark_hit(buffer, cpu, full))
+ return true;
- if (full)
- prepare_to_wait(&work->full_waiters, &wait, TASK_INTERRUPTIBLE);
- else
- prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE);
+ if (cond(data))
+ return true;
/*
* The events can happen in critical sections where
* a task has been queued. It's OK for spurious wake ups.
*/
if (full)
- work->full_waiters_pending = true;
+ rbwork->full_waiters_pending = true;
else
- work->waiters_pending = true;
+ rbwork->waiters_pending = true;
- if (rb_watermark_hit(buffer, cpu, full))
- goto out;
+ return false;
+}
- if (signal_pending(current)) {
- ret = -EINTR;
- goto out;
+/*
+ * The default wait condition for ring_buffer_wait() is to just to exit the
+ * wait loop the first time it is woken up.
+ */
+static bool rb_wait_once(void *data)
+{
+ long *once = data;
+
+ /* wait_event() actually calls this twice before scheduling*/
+ if (*once > 1)
+ return true;
+
+ (*once)++;
+ return false;
+}
+
+/**
+ * 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 the percentage of pages are 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 trace_buffer *buffer, int cpu, int full)
+{
+ struct ring_buffer_per_cpu *cpu_buffer;
+ struct wait_queue_head *waitq;
+ ring_buffer_cond_fn cond;
+ struct rb_irq_work *rbwork;
+ void *data;
+ long once = 0;
+ int ret = 0;
+
+ cond = rb_wait_once;
+ data = &once;
+
+ /*
+ * Depending on what the caller is waiting for, either any
+ * data in any cpu buffer, or a specific buffer, put the
+ * caller on the appropriate wait queue.
+ */
+ if (cpu == RING_BUFFER_ALL_CPUS) {
+ rbwork = &buffer->irq_work;
+ /* Full only makes sense on per cpu reads */
+ full = 0;
+ } else {
+ if (!cpumask_test_cpu(cpu, buffer->cpumask))
+ return -ENODEV;
+ cpu_buffer = buffer->buffers[cpu];
+ rbwork = &cpu_buffer->irq_work;
}
- schedule();
- out:
if (full)
- finish_wait(&work->full_waiters, &wait);
+ waitq = &rbwork->full_waiters;
else
- finish_wait(&work->waiters, &wait);
+ waitq = &rbwork->waiters;
- if (!ret && !rb_watermark_hit(buffer, cpu, full) && signal_pending(current))
- ret = -EINTR;
+ ret = wait_event_interruptible((*waitq),
+ rb_wait_cond(rbwork, buffer, cpu, full, cond, data));
return ret;
}