tracing: Do not risk busy looping in buffer splice (07906da7) · Commits · 戴 / test

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:

Rabin Vincent <rabin@rab.in> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

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;

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