tracing: Clean up tracing_fill_pipe_page() (74f06bb7) · Commits · 戴 / test

The function tracing_fill_pipe_page() logic is a little confusing with the use of count saving the seq.len and reusing it. Instead of subtracting a number that is calculated from the saved value of the seq.len from seq.len, just save the seq.len at the start and if we need to reset it, just assign it again. When the seq_buf overflow is len == size + 1, the current logic will break. Changing it to use a saved length for resetting back to the original value is more robust and will work when we change the way seq_buf sets the overflow. Link: http://lkml.kernel.org/r/20141118161546.GJ23958@pathway.suse.cz Reviewed-by:

Petr Mladek <pmladek@suse.cz> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

+19 −6

Original line number	Diff line number	Diff line
		@@ -4575,20 +4575,33 @@ static size_t
		tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
		{
		size_t count;
		int save_len;
		int ret;

		/* Seq buffer is page-sized, exactly what we need. */
		for (;;) {
		count = iter->seq.seq.len;
		save_len = iter->seq.seq.len;
		ret = print_trace_line(iter);
		count = iter->seq.seq.len - count;
		if (rem < count) {
		rem = 0;
		iter->seq.seq.len -= count;

		if (trace_seq_has_overflowed(&iter->seq)) {
		iter->seq.seq.len = save_len;
		break;
		}

		/*
		* This should not be hit, because it should only
		* be set if the iter->seq overflowed. But check it
		* anyway to be safe.
		*/
		if (ret == TRACE_TYPE_PARTIAL_LINE) {
		iter->seq.seq.len -= count;
		iter->seq.seq.len = save_len;
		break;
		}

		count = iter->seq.seq.len - save_len;
		if (rem < count) {
		rem = 0;
		iter->seq.seq.len = save_len;
		break;
		}

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