#include <linux/trace_clock.h>
#include <linux/trace_seq.h>
#include <linux/spinlock.h>
+#include <linux/irq_work.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
return ret;
}
+struct rb_irq_work {
+ struct irq_work work;
+ wait_queue_head_t waiters;
+ bool waiters_pending;
+};
+
/*
* head_page == tail_page && head == tail then buffer is empty.
*/
struct list_head new_pages; /* new pages to add */
struct work_struct update_pages_work;
struct completion update_done;
+
+ struct rb_irq_work irq_work;
};
struct ring_buffer {
struct notifier_block cpu_notify;
#endif
u64 (*clock)(void);
+
+ struct rb_irq_work irq_work;
};
struct ring_buffer_iter {
u64 read_stamp;
};
+/*
+ * rb_wake_up_waiters - wake up tasks waiting for ring buffer input
+ *
+ * Schedules a delayed work to wake up any task that is blocked on the
+ * ring buffer waiters queue.
+ */
+static void rb_wake_up_waiters(struct irq_work *work)
+{
+ struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work);
+
+ wake_up_all(&rbwork->waiters);
+}
+
+/**
+ * ring_buffer_wait - wait for input to the ring buffer
+ * @buffer: buffer to wait on
+ * @cpu: the cpu buffer to wait on
+ *
+ * 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.
+ */
+void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
+{
+ struct ring_buffer_per_cpu *cpu_buffer;
+ DEFINE_WAIT(wait);
+ struct rb_irq_work *work;
+
+ /*
+ * 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;
+ else {
+ cpu_buffer = buffer->buffers[cpu];
+ work = &cpu_buffer->irq_work;
+ }
+
+
+ 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;
+
+ 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);
+}
+
+/**
+ * ring_buffer_poll_wait - poll on buffer input
+ * @buffer: buffer to wait on
+ * @cpu: the cpu buffer to wait on
+ * @filp: the file descriptor
+ * @poll_table: The poll descriptor
+ *
+ * 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.
+ *
+ * Returns POLLIN | POLLRDNORM if data exists in the buffers,
+ * zero otherwise.
+ */
+int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
+ struct file *filp, poll_table *poll_table)
+{
+ struct ring_buffer_per_cpu *cpu_buffer;
+ struct rb_irq_work *work;
+
+ if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
+ (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
+ return POLLIN | POLLRDNORM;
+
+ if (cpu == RING_BUFFER_ALL_CPUS)
+ work = &buffer->irq_work;
+ else {
+ cpu_buffer = buffer->buffers[cpu];
+ work = &cpu_buffer->irq_work;
+ }
+
+ work->waiters_pending = true;
+ poll_wait(filp, &work->waiters, poll_table);
+
+ if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
+ (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
+ return POLLIN | POLLRDNORM;
+ return 0;
+}
+
/* buffer may be either ring_buffer or ring_buffer_per_cpu */
#define RB_WARN_ON(b, cond) \
({ \
cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler);
init_completion(&cpu_buffer->update_done);
+ init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters);
bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
GFP_KERNEL, cpu_to_node(cpu));
buffer->clock = trace_clock_local;
buffer->reader_lock_key = key;
+ init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters);
+
/* need at least two pages */
if (nr_pages < 2)
nr_pages = 2;
rb_end_commit(cpu_buffer);
}
+static __always_inline void
+rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
+{
+ if (buffer->irq_work.waiters_pending) {
+ buffer->irq_work.waiters_pending = false;
+ /* irq_work_queue() supplies it's own memory barriers */
+ irq_work_queue(&buffer->irq_work.work);
+ }
+
+ if (cpu_buffer->irq_work.waiters_pending) {
+ cpu_buffer->irq_work.waiters_pending = false;
+ /* irq_work_queue() supplies it's own memory barriers */
+ irq_work_queue(&cpu_buffer->irq_work.work);
+ }
+}
+
/**
* ring_buffer_unlock_commit - commit a reserved
* @buffer: The buffer to commit to
rb_commit(cpu_buffer, event);
+ rb_wakeups(buffer, cpu_buffer);
+
trace_recursive_unlock();
preempt_enable_notrace();
rb_commit(cpu_buffer, event);
+ rb_wakeups(buffer, cpu_buffer);
+
ret = 0;
out:
preempt_enable_notrace();
#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>
*/
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
#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 |
TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
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
*
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);
}
/**
__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);
}
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
#endif
trace_init_cmdlines();
- init_irq_work(&trace_work_wakeup, trace_wake_up);
register_tracer(&nop_trace);
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