On Wed, Jan 02, 2019 at 09:30:24PM +0200, Leon Romanovsky wrote:
> > struct ib_umad_file {
> > struct mutex mutex;
> > struct ib_umad_port *port;
> > struct list_head recv_list;
> > struct list_head send_list;
> > struct list_head port_list;
> > spinlock_t send_lock;
> > wait_queue_head_t recv_wait;
> > struct ib_mad_agent *agent[IB_UMAD_MAX_AGENTS];
> > int agents_dead;
> > u8 use_pkey_index;
> > u8 already_used;
> > };
> >
> > No 'ib_umad_device' in there.
>
> At the beginning of ib_umad_close(), there is a line:
> struct ib_umad_device *dev = file->port->umad_dev;
>
> Because "dev" is not used before ib_umad_dev_put(), compiler probably
> defers evaluation of dev pointer till the end, after "kfree(file);".
C does not allow that kind of re-ordering.
> I don't know what about others, but for us this patch gave two weeks
> of clean runs without traces, which is not the case without it.
Come up with an explanation why it works then?
Thanks
Jason
