On Fri, Feb 03, 2017 at 02:38:35PM +0100, Hannes Reinecke wrote:
> On 02/03/2017 02:31 PM, Christoph Hellwig wrote:
> >> - if (sg_res_in_use(sfp)) {
> >> + mutex_lock(&sfp->f_mutex);
> >> + if (sfp->res_in_use) {
> >> + mutex_unlock(&sfp->f_mutex);
> >> sg_remove_request(sfp, srp);
> >> return -EBUSY; /* reserve buffer already being used */
> >> }
> >> + mutex_unlock(&sfp->f_mutex);
> >
> > Holding a mutex over a the check of a single scalar doesn't make sense.
> >
> It's adds a synchronisation point, doesn't it?
It does, but it doesn't actually protect anything..
