[PATCH 21/31] blk-throttle: implement sq_to_tg(), sq_to_td() and throtl_log()

[Vivek Goyal]

On Mon, May 06, 2013 at 01:38:27PM -0700, Tejun Heo wrote:
> On Mon, May 06, 2013 at 01:36:44PM -0400, Vivek Goyal wrote:
> > On Wed, May 01, 2013 at 05:39:39PM -0700, Tejun Heo wrote:
> > 
> > [..]
> > > +#define throtl_log(sq, fmt, args...)	do {				\
> > > +	struct throtl_grp *__tg = sq_to_tg((sq));			\
> > > +	struct throtl_data *__td = sq_to_td((sq));			\
> > >  	char __pbuf[128];						\
> > >  									\
> > > -	blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf));		\
> > > -	blk_add_trace_msg((tg)->td->queue, "throtl %s " fmt, __pbuf, ##args); \
> > > +	__pbuf[0] = ' ';						\
> > > +	__pbuf[1] = '\0';						\
> > > +	if ((__tg))							\
> > > +		blkg_path(tg_to_blkg(__tg), __pbuf + 1, sizeof(__pbuf) - 1); \
> > > +	blk_add_trace_msg(__td->queue, "throtl%s" fmt, __pbuf, ##args); \
> > 
> > We need one extra space ("throtl%s "), otherwise all the messages
> > start right after cgroup path. We need a space between cgroup path
> > and actual message.
> 
> Okay, we don't - __pbuf[0] = ' '.  The reason it's doing the above
> instead of "throtl %s " is because when the path is nil, we don't
> wanna print out two consecutive spaces, so AFAICS the code is correct.

What about space after the cgroup path info (when path is not nil).

Vivek