Aya,
thanks for this patch and thanks for calling our attention to this
future problem in our code. Here you come up with a solution optimized
for "accuracy", but you mention already an alternative solution
optimized for "speed". In ctcm the time stamps are just used to deliver
a statistic value. Since the time stamps are used in the hot traffic
path of the ctcm-driver, I prefer the "speed" optimized solution based
on jiffies here.
Regards, Ursula Braun
On Wed, 2014-10-29 at 18:02 +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. timespec64 and unsigned long long were used
> instead of timespec and unsigned long respectively in two files.
> All timespec variables use monotonic time values through the function
> ktime_get_ts64(). This is to make sure that all the time values
> are calculated from a fixed point.
>
> Signed-off-by: Aya Mahfouz <mahfouz.saif.elya...@gmail.com>
> ---
> 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 and current_kernel_time().
>
> drivers/s390/net/ctcm_fsms.c | 18 +++++++++++-------
> drivers/s390/net/ctcm_main.h | 4 ++--
> 2 files changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/s390/net/ctcm_fsms.c b/drivers/s390/net/ctcm_fsms.c
> index fb92524..233aef8 100644
> --- a/drivers/s390/net/ctcm_fsms.c
> +++ b/drivers/s390/net/ctcm_fsms.c
> @@ -250,8 +250,10 @@ static void chx_txdone(fsm_instance *fi, int event, void
> *arg)
> struct sk_buff *skb;
> int first = 1;
> int i;
> - unsigned long duration;
> - struct timespec done_stamp = current_kernel_time(); /* xtime */
> + unsigned long long duration;
> + struct timespec64 done_stamp;
> +
> + ktime_get_ts64(&done_stamp);
>
> CTCM_PR_DEBUG("%s(%s): %s\n", __func__, ch->id, dev->name);
>
> @@ -307,7 +309,7 @@ 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 */
> + ktime_get_ts64(&ch->prof.sendstamp);
> rc = ccw_device_start(ch->cdev, &ch->ccw[0],
> (unsigned long)ch, 0xff, 0);
> ch->prof.doios_multi++;
> @@ -1224,12 +1226,14 @@ static void ctcmpc_chx_txdone(fsm_instance *fi, int
> event, void *arg)
> int first = 1;
> int i;
> __u32 data_space;
> - unsigned long duration;
> + unsigned long long duration;
> struct sk_buff *peekskb;
> int rc;
> struct th_header *header;
> struct pdu *p_header;
> - struct timespec done_stamp = current_kernel_time(); /* xtime */
> + struct timespec64 done_stamp;
> +
> + ktime_get_ts64(&done_stamp);
>
> CTCM_PR_DEBUG("Enter %s: %s cp:%i\n",
> __func__, dev->name, smp_processor_id());
> @@ -1361,7 +1365,7 @@ 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 */
> + ktime_get_ts64(&ch->prof.send_stamp);
> 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 +1831,7 @@ 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 */
> + ktime_get_ts64(&wch->prof.send_stamp);
> 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..ed7d44a 100644
> --- a/drivers/s390/net/ctcm_main.h
> +++ b/drivers/s390/net/ctcm_main.h
> @@ -120,8 +120,8 @@ struct ctcm_profile {
> unsigned long doios_single;
> unsigned long doios_multi;
> unsigned long txlen;
> - unsigned long tx_time;
> - struct timespec send_stamp;
> + unsigned long long tx_time;
> + struct timespec64 send_stamp;
> };
>
> /*
--
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