Re: [PATCH] tools lib traceevent: Use helper trace-seq in print functions like kernel does

[Jiri Olsa <jolsa@redhat.com>]

On Tue, Nov 19, 2013 at 06:29:37PM -0500, Steven Rostedt wrote:
> Jiri Olso reported that his plugin for scsi was chopping off part of

s/Olso/Olsa/ 

;-)

> the output. Investigating this, I found that Jiri used the same
> functions as what is in the kernel, which adds the following:
> 
> 	trace_seq_putc(p, 0);
> 
> This adds a '\0' to the output string. The reason this works in the
> kernel is that the "p" that is passed to the function helper is a
> temporary trace_seq. But in the libtraceevent library, it's the pointer
> to the trace_seq used to output. By adding the '\0', it truncates the
> line and nothing added after that will be printed.
> 
> We can solve this in two ways. One is to have the helper functions for
> the library not add the unnecessary '\0'. The other is to change the
> library to also use a helper trace_seq structure that gets copied to
> the main trace_seq just like the kernel does.
> 
> The latter allows the helper functions in the plugins to be the same as
> the kernel, which is the better solution.
> 
> Reported-by: Jiri Olsa <jolsa@redhat.com>

Tested-by: Jiri Olsa <jolsa@redhat.com>

thanks,
jirka