ftrace: allow the event pipe to be polled (2a2cc8f7) · Commits · e / devices / kernel_gigaset_gs290

kernel/trace/trace.c

+38 −1

Original line number	Diff line number	Diff line
		@@ -24,6 +24,7 @@
		#include <linux/percpu.h>
		#include <linux/ctype.h>
		#include <linux/init.h>
		#include <linux/poll.h>
		#include <linux/gfp.h>
		#include <linux/fs.h>

		@@ -63,6 +64,7 @@ static struct tracer *current_trace __read_mostly;
		static int max_tracer_type_len;

		static DEFINE_MUTEX(trace_types_lock);
		static DECLARE_WAIT_QUEUE_HEAD (trace_wait);

		#define ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(struct trace_entry))

		@@ -105,6 +107,7 @@ enum trace_iterator_flags {
		TRACE_ITER_RAW = 0x10,
		TRACE_ITER_HEX = 0x20,
		TRACE_ITER_BIN = 0x40,
		TRACE_ITER_BLOCK = 0x80,
		};

		#define TRACE_ITER_SYM_MASK \
		@@ -119,6 +122,7 @@ static const char *trace_options[] = {
		"raw",
		"hex",
		"bin",
		"block",
		NULL
		};

		@@ -650,6 +654,9 @@ __ftrace(struct trace_array tr, struct trace_array_cpu data,
		entry->fn.ip = ip;
		entry->fn.parent_ip = parent_ip;
		spin_unlock_irqrestore(&data->lock, irq_flags);

		if (!(trace_flags & TRACE_ITER_BLOCK))
		wake_up (&trace_wait);
		}

		notrace void
		@@ -675,6 +682,9 @@ trace_special(struct trace_array tr, struct trace_array_cpu data,
		entry->special.arg2 = arg2;
		entry->special.arg3 = arg3;
		spin_unlock_irqrestore(&data->lock, irq_flags);

		if (!(trace_flags & TRACE_ITER_BLOCK))
		wake_up (&trace_wait);
		}

		notrace void
		@@ -696,6 +706,9 @@ tracing_sched_switch_trace(struct trace_array *tr,
		entry->ctx.next_pid = next->pid;
		entry->ctx.next_prio = next->prio;
		spin_unlock_irqrestore(&data->lock, irq_flags);

		if (!(trace_flags & TRACE_ITER_BLOCK))
		wake_up (&trace_wait);
		}

		#ifdef CONFIG_FTRACE
		@@ -1765,7 +1778,6 @@ static struct file_operations tracing_readme_fops = {
		.read = tracing_readme_read,
		};


		static ssize_t
		tracing_ctrl_read(struct file filp, char __user ubuf,
		size_t cnt, loff_t *ppos)
		@@ -1953,6 +1965,28 @@ static int tracing_release_pipe(struct inode inode, struct file file)
		return 0;
		}

		static unsigned int
		tracing_poll_pipe(struct file filp, poll_table poll_table)
		{
		struct trace_iterator *iter = filp->private_data;

		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;
		poll_wait(filp, &trace_wait, poll_table);
		if (!trace_empty(iter))
		return POLLIN \| POLLRDNORM;

		return 0;
		}
		}

		/*
		* Consumer reader.
		*/
		@@ -1991,6 +2025,8 @@ tracing_read_pipe(struct file filp, char __user ubuf,
		start = 0;

		while (trace_empty(iter)) {
		if (!(trace_flags & TRACE_ITER_BLOCK))
		return -EWOULDBLOCK;
		/*
		* This is a make-shift waitqueue. The reason we don't use
		* an actual wait queue is because:
		@@ -2134,6 +2170,7 @@ static struct file_operations set_tracer_fops = {

		static struct file_operations tracing_pipe_fops = {
		.open = tracing_open_pipe,
		.poll = tracing_poll_pipe,
		.read = tracing_read_pipe,
		.release = tracing_release_pipe,
		};