Re: [RFC][PATCH 2/2] tracing: Do not return EINVAL in snapshot when not allocated

[Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>]

(03/06/2013 10:49 PM), Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)"<srostedt@redhat.com>
> 
> To use the tracing snapshot feature, writing a '1' into the snapshot
> file causes the snapshot buffer to be allocated if it has not already
> been allocated and dose a 'swap' with the main buffer, so that the
> snapshot now contains what was in the main buffer, and the main buffer
> now writes to what was the snapshot buffer.
> 
> To free the snapshot buffer, a '0' is written into the snapshot file.
> 
> To clear the snapshot buffer, any number but a '0' or '1' is written
> into the snapshot file. But if the file is not allocated it returns
> -EINVAL error code. This is rather pointless. It is better just to
> do nothing and return success.
> 
> Cc: Hiraku Toyooka<hiraku.toyooka.gu@hitachi.com>
> Signed-off-by: Steven Rostedt<rostedt@goodmis.org>
> ---

Acked-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>

>   kernel/trace/trace.c |    2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 9e3120b..1f835a8 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -4167,8 +4167,6 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
>   	default:
>   		if (current_trace->allocated_snapshot)
>   			tracing_reset_online_cpus(&max_tr);
> -		else
> -			ret = -EINVAL;
>   		break;
>   	}
>   
> -- 1.7.10.4 .
>