#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
static int trace_stop_count;
static DEFINE_RAW_SPINLOCK(tracing_start_lock);
-static void wakeup_work_handler(struct work_struct *work)
+/**
+ * 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(&trace_wait);
-}
+ wake_up_all(&trace_wait);
-static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
+}
/**
* tracing_on - enable tracing buffers
}
EXPORT_SYMBOL_GPL(tracing_is_on);
-/**
- * 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.
- */
-void trace_wake_up(void)
-{
- const unsigned long delay = msecs_to_jiffies(2);
-
- if (trace_flags & TRACE_ITER_BLOCK)
- return;
- schedule_delayed_work(&wakeup_work, delay);
-}
-
static int __init set_buf_size(char *str)
{
unsigned long buf_size;
}
#endif /* CONFIG_TRACER_MAX_TRACE */
+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();
+
+ finish_wait(&trace_wait, &wait);
+}
+
/**
* register_tracer - register a tracer with the ftrace system.
* @type - the plugin for the tracer
__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 inline void
__trace_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
- unsigned long flags, int pc,
- int wake)
+ unsigned long flags, int pc)
{
__buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);
ftrace_trace_userstack(buffer, flags, pc);
-
- if (wake)
- trace_wake_up();
}
void trace_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
- __trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
+ __trace_buffer_unlock_commit(buffer, event, flags, pc);
}
+EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit);
struct ring_buffer_event *
trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
- __trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
+ __trace_buffer_unlock_commit(buffer, event, flags, pc);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
-void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
- struct ring_buffer_event *event,
- unsigned long flags, int pc)
-{
- __trace_buffer_unlock_commit(buffer, event, flags, pc, 0);
-}
-EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
-
-void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
- struct ring_buffer_event *event,
- unsigned long flags, int pc,
- struct pt_regs *regs)
+void trace_buffer_unlock_commit_regs(struct ring_buffer *buffer,
+ struct ring_buffer_event *event,
+ unsigned long flags, int pc,
+ struct pt_regs *regs)
{
__buffer_unlock_commit(buffer, event);
ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
ftrace_trace_userstack(buffer, flags, pc);
}
-EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit_regs);
+EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit_regs);
void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event)
}
}
-
-void default_wait_pipe(struct trace_iterator *iter)
-{
- DEFINE_WAIT(wait);
-
- prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
-
- if (trace_empty(iter))
- schedule();
-
- finish_wait(&trace_wait, &wait);
-}
-
/*
* This is a make-shift waitqueue.
* A tracer might use this callback on some rare cases:
#endif
trace_init_cmdlines();
+ init_irq_work(&trace_work_wakeup, trace_wake_up);
register_tracer(&nop_trace);
current_trace = &nop_trace;
projects / firefly-linux-kernel-4.4.55.git / commitdiff