Re: [PATCH v2] drivers: s390: net: ctcm: migrate variables to handle y2038 problem

[Aya Mahfouz]

On Fri, Oct 31, 2014 at 02:38:35PM +0100, Ursula Braun wrote:
> thanks, Aya. I miss drivers/s390/net/ctcm_main.c in your patch. And

Hello Ursula,
 ok. I will see what needs to do in it. I did not change it.

> "time_before()" is not the right function to use here, because it
> returns a Bool value. Purpose of the ctcm timespec stuff is to determine
> the time interval between triggering the send operation and receiving
> the confirmation of the send operation. The maximum value is saved and
> can be displayed in the statistics.

Yes, you're right. I will fix that. Sorry!
> 
> Regards, Ursula Braun
> 

Kind Regards,
Aya Saif El-yazal Mahfouz

> On Fri, 2014-10-31 at 11:18 +0200, Aya Mahfouz wrote:
> > This patch is concerned with migrating the time variables for the s390
> > network driver. The changes handle the y2038 problem where timespec will
> > overflow in the year 2038. timespec was replaced by unsigned long and
> > all time variables get their values from the jiffies global variable.
> > This was done for the sake of speed and efficiency.
> > 
> > Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@xxxxxxxxx>
> > ---
> > v1: Arnd has advised me to provide you with options for time
> >     calculation. The first option: "accuracy" is used in this
> >     patch. The second option: "speed" can be done through
> >     jiffies.
> > 
> > v2: Moved on to the speed option. Let me know if I explicitly
> >     need to include the jiffies header. The module compiles with
> >     no problems on my side.
> > 
> >  drivers/s390/net/ctcm_fsms.c | 18 +++++++-----------
> >  drivers/s390/net/ctcm_main.h |  2 +-
> >  2 files changed, 8 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/s390/net/ctcm_fsms.c b/drivers/s390/net/ctcm_fsms.c
> > index fb92524..34b9820 100644
> > --- a/drivers/s390/net/ctcm_fsms.c
> > +++ b/drivers/s390/net/ctcm_fsms.c
> > @@ -251,13 +251,11 @@ static void chx_txdone(fsm_instance *fi, int event, void *arg)
> >  	int first = 1;
> >  	int i;
> >  	unsigned long duration;
> > -	struct timespec done_stamp = current_kernel_time(); /* xtime */
> > +	unsigned long done_stamp = jiffies;
> > 
> >  	CTCM_PR_DEBUG("%s(%s): %s\n", __func__, ch->id, dev->name);
> > 
> > -	duration =
> > -	    (done_stamp.tv_sec - ch->prof.send_stamp.tv_sec) * 1000000 +
> > -	    (done_stamp.tv_nsec - ch->prof.send_stamp.tv_nsec) / 1000;
> > +	duration = time_before(done_stamp, ch->prof.send_stamp);
> >  	if (duration > ch->prof.tx_time)
> >  		ch->prof.tx_time = duration;
> > 
> > @@ -307,7 +305,7 @@ static void chx_txdone(fsm_instance *fi, int event, void *arg)
> >  		spin_unlock(&ch->collect_lock);
> >  		ch->ccw[1].count = ch->trans_skb->len;
> >  		fsm_addtimer(&ch->timer, CTCM_TIME_5_SEC, CTC_EVENT_TIMER, ch);
> > -		ch->prof.send_stamp = current_kernel_time(); /* xtime */
> > +		ch->prof.send_stamp = jiffies;
> >  		rc = ccw_device_start(ch->cdev, &ch->ccw[0],
> >  						(unsigned long)ch, 0xff, 0);
> >  		ch->prof.doios_multi++;
> > @@ -1229,14 +1227,12 @@ static void ctcmpc_chx_txdone(fsm_instance *fi, int event, void *arg)
> >  	int		rc;
> >  	struct th_header *header;
> >  	struct pdu	*p_header;
> > -	struct timespec done_stamp = current_kernel_time(); /* xtime */
> > +	unsigned long done_stamp = jiffies;
> > 
> >  	CTCM_PR_DEBUG("Enter %s: %s cp:%i\n",
> >  			__func__, dev->name, smp_processor_id());
> > 
> > -	duration =
> > -		(done_stamp.tv_sec - ch->prof.send_stamp.tv_sec) * 1000000 +
> > -		(done_stamp.tv_nsec - ch->prof.send_stamp.tv_nsec) / 1000;
> > +	duration = time_before(done_stamp, ch->prof.send_stamp);
> >  	if (duration > ch->prof.tx_time)
> >  		ch->prof.tx_time = duration;
> > 
> > @@ -1361,7 +1357,7 @@ static void ctcmpc_chx_txdone(fsm_instance *fi, int event, void *arg)
> > 
> >  	ch->ccw[1].count = ch->trans_skb->len;
> >  	fsm_addtimer(&ch->timer, CTCM_TIME_5_SEC, CTC_EVENT_TIMER, ch);
> > -	ch->prof.send_stamp = current_kernel_time(); /* xtime */
> > +	ch->prof.send_stamp = jiffies;
> >  	if (do_debug_ccw)
> >  		ctcmpc_dumpit((char *)&ch->ccw[0], sizeof(struct ccw1) * 3);
> >  	rc = ccw_device_start(ch->cdev, &ch->ccw[0],
> > @@ -1827,7 +1823,7 @@ static void ctcmpc_chx_send_sweep(fsm_instance *fsm, int event, void *arg)
> >  	fsm_newstate(wch->fsm, CTC_STATE_TX);
> > 
> >  	spin_lock_irqsave(get_ccwdev_lock(wch->cdev), saveflags);
> > -	wch->prof.send_stamp = current_kernel_time(); /* xtime */
> > +	wch->prof.send_stamp = jiffies;
> >  	rc = ccw_device_start(wch->cdev, &wch->ccw[3],
> >  					(unsigned long) wch, 0xff, 0);
> >  	spin_unlock_irqrestore(get_ccwdev_lock(wch->cdev), saveflags);
> > diff --git a/drivers/s390/net/ctcm_main.h b/drivers/s390/net/ctcm_main.h
> > index 477c933..6f4417c 100644
> > --- a/drivers/s390/net/ctcm_main.h
> > +++ b/drivers/s390/net/ctcm_main.h
> > @@ -121,7 +121,7 @@ struct ctcm_profile {
> >  	unsigned long doios_multi;
> >  	unsigned long txlen;
> >  	unsigned long tx_time;
> > -	struct timespec send_stamp;
> > +	unsigned long send_stamp;
> >  };
> > 
> >  /*
> 
> 
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