Re: [PATCH tracing/kprobes 3/3] tracing/ftrace: Fix to check create_event_dir() when adding new events

[Frederic Weisbecker <fweisbec@gmail.com>]

On Fri, Sep 25, 2009 at 11:20:54AM -0700, Masami Hiramatsu wrote:
> Check result of create_event_dir() and add ftrace_event_call to
> ftrace_events list only if it is succeeded. Thanks Li for pointing it out.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Jim Keniston <jkenisto@us.ibm.com>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Frank Ch. Eigler <fche@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Jason Baron <jbaron@redhat.com>
> Cc: K.Prasad <prasad@linux.vnet.ibm.com>
> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Tom Zanussi <tzanussi@gmail.com>
> ---
> 
>  kernel/trace/trace_events.c |   29 +++++++++++++++++++++--------
>  1 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index a4b7c9a..f03cda3 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -957,12 +957,14 @@ static int __trace_add_event_call(struct ftrace_event_call *call)
>  	if (!d_events)
>  		return -ENOENT;
>  
> -	list_add(&call->list, &ftrace_events);
>  	ret = event_create_dir(call, d_events, &ftrace_event_id_fops,
>  				&ftrace_enable_fops, &ftrace_event_filter_fops,
>  				&ftrace_event_format_fops);
>  	if (ret < 0)
> -		list_del(&call->list);
> +		pr_warning("Could not create directory of trace events/%s\n",
> +			   call->name);




We already have such warnings in event_create_dir, with even more granularity
against the failure reason. The patch is fine, but I'll just remove the warning
introduced inside while applying it.

Thanks.


PS: Also I guess we could add the event in the list right from
event_create_dir()...