Re: [PATCH tip/master] tracing/probes: Fix a warning message to show correct maximum length

[Masami Hiramatsu]

On Tue, 7 Feb 2017 08:41:48 +0100
Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> 
> * Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> 
> > Since tracing/*probe_events will accept a probe definition
> > up to 4096 - 2 ('\n' and '\0') bytes, it must show 4094 instead
> > of 4096 in warning message.
> > 
> > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > ---
> >  kernel/trace/trace_probe.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> > index 8c0553d..7138fea 100644
> > --- a/kernel/trace/trace_probe.c
> > +++ b/kernel/trace/trace_probe.c
> > @@ -673,8 +673,9 @@ ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
> >  			*tmp = '\0';
> >  			size = tmp - kbuf + 1;
> >  		} else if (done + size < count) {
> > +			/* This can accept WRITE_BUFSIZE - 2 ('\n' + '\0') */
> >  			pr_warn("Line length is too long: Should be less than %d\n",
> > -				WRITE_BUFSIZE);
> > +				WRITE_BUFSIZE - 2);
> 
> The message should also indicate which kernel subsystem generated it - which is 
> useful if the message is not immediately noticed in the kernel log.
> 
> You can do this by having something like this at the top of the trace_probe file:
> 
>   #define pr_fmt(fmt) "trace_probe: " fmt

Ah, I got it. I'll make a separate patch for that.

Thank you!

-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>