Re: [PATCH] tracing: add checks for printing graph irq

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 2009-12-11 at 17:38 +0800, Wenji Huang wrote:
> Check return value of trace_seq_printf.
> 
> Signed-off-by: Wenji Huang <wenji.huang@oracle.com>
> ---
>  kernel/trace/trace_functions_graph.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 45e6c01..3fa4055 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -555,8 +555,11 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
>  		return TRACE_TYPE_PARTIAL_LINE;
>  
>  	/* Don't close the duration column if haven't one */
> -	if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
> -		trace_seq_printf(s, " |");
> +	if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
> +		ret = trace_seq_printf(s, " |");
> +		if (!ret)
> +			return TRACE_TYPE_PARTIAL_LINE;
> +	}
>  	ret = trace_seq_printf(s, "\n");

Actually these checks are no longer needed. I would like to start
removing them. Only the last one is needed.

This is because trace_seq_* now has a "full" attribute. If the s buffer
gets full, it wont write anymore, and all new "trace_seq_*" calls will
return the same.

-- Steve

>  
>  	if (!ret)