Commit 34cd4998 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

tracing: clean up splice code 



Ingo Molnar suggested a series of clean ups for the splice code.
This patch implements those suggestions.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent ff98781b

kernel/trace/trace.c

+55 −41
Original line number Diff line number Diff line
@@ -2546,6 +2546,40 @@ static struct pipe_buf_operations tracing_pipe_buf_ops = { 
	.get			= generic_pipe_buf_get,

};



static size_t

tracing_fill_pipe_page(struct page *pages, size_t rem,

			struct trace_iterator *iter)

{

	size_t count;

	int ret;



	/* Seq buffer is page-sized, exactly what we need. */

	for (;;) {

		count = iter->seq.len;

		ret = print_trace_line(iter);

		count = iter->seq.len - count;

		if (rem < count) {

			rem = 0;

			iter->seq.len -= count;

			break;

		}

		if (ret == TRACE_TYPE_PARTIAL_LINE) {

			iter->seq.len -= count;

			break;

		}



		trace_consume(iter);

		rem -= count;

		if (!find_next_entry_inc(iter))	{

			rem = 0;

			iter->ent = NULL;

			break;

		}

	}



	return rem;

}



static ssize_t tracing_splice_read_pipe(struct file *filp,

					loff_t *ppos,

					struct pipe_inode_info *pipe,
@@ -2564,7 +2598,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, 
		.spd_release	= tracing_spd_release_pipe,

	};

	ssize_t ret;

	size_t count, rem;

	size_t rem;

	unsigned int i;



	mutex_lock(&trace_types_lock);
@@ -2573,45 +2607,25 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, 
		ret = iter->trace->splice_read(iter, filp,

					       ppos, pipe, len, flags);

		if (ret)

			goto out;

			goto out_err;

	}



	ret = tracing_wait_pipe(filp);

	if (ret <= 0)

		goto out;

		goto out_err;



	if (!iter->ent && !find_next_entry_inc(iter)) {

		ret = -EFAULT;

		goto out;

		goto out_err;

	}



	/* Fill as many pages as possible. */

	for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {

		pages[i] = alloc_page(GFP_KERNEL);



		/* Seq buffer is page-sized, exactly what we need. */

		for (;;) {

			count = iter->seq.len;

			ret = print_trace_line(iter);

			count = iter->seq.len - count;

			if (rem < count) {

				rem = 0;

				iter->seq.len -= count;

		if (!pages[i])

			break;

			}

			if (ret == TRACE_TYPE_PARTIAL_LINE) {

				iter->seq.len -= count;

				break;

			}



			trace_consume(iter);

			rem -= count;

			if (!find_next_entry_inc(iter))	{

				rem = 0;

				iter->ent = NULL;

				break;

			}

		}

		rem = tracing_fill_pipe_page(pages[i], rem, iter);



		/* Copy the data into the page, so we can start over. */

		ret = trace_seq_to_buffer(&iter->seq,
@@ -2633,7 +2647,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, 


	return splice_to_pipe(pipe, &spd);



out:

out_err:

	mutex_unlock(&trace_types_lock);



	return ret;