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Commit 07906da7 authored by Rabin Vincent's avatar Rabin Vincent Committed by Steven Rostedt
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tracing: Do not risk busy looping in buffer splice 

If the read loop in trace_buffers_splice_read() keeps failing due to
memory allocation failures without reading even a single page then this
function will keep busy looping.

Remove the risk for that by exiting the function if memory allocation
failures are seen.

Link: http://lkml.kernel.org/r/1415309167-2373-2-git-send-email-rabin@rab.in



Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent e30f53aa

kernel/trace/trace.c

+8 −2
Original line number Diff line number Diff line
@@ -5494,7 +5494,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, 
	};

	struct buffer_ref *ref;

	int entries, size, i;

	ssize_t ret;

	ssize_t ret = 0;



	mutex_lock(&trace_types_lock);
@@ -5532,13 +5532,16 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, 
		int r;



		ref = kzalloc(sizeof(*ref), GFP_KERNEL);

		if (!ref)

		if (!ref) {

			ret = -ENOMEM;

			break;

		}



		ref->ref = 1;

		ref->buffer = iter->trace_buffer->buffer;

		ref->page = ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file);

		if (!ref->page) {

			ret = -ENOMEM;

			kfree(ref);

			break;

		}
@@ -5576,6 +5579,9 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, 


	/* did we read anything? */

	if (!spd.nr_pages) {

		if (ret)

			goto out;



		if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) {

			ret = -EAGAIN;

			goto out;