Re: [PATCH v3] drivers: s390: net: ctcm: migrate variables to handle y2038 problem

[Ursula Braun]

Thx, Aya. Now I will add your patch to our collection for our next
upstream posting on net_next.
The only thing I want to change is removing your
	#include <linux/jiffies.h>
lines. All affected routines use already
	#include <linux/timer.h>
Thus these lines are not needed.

Regards, Ursula Braun

On Sat, 2014-11-01 at 02:16 +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.
> 
> v3: Handled the error pointed out by Ursula. The current version
>     does not handle overflows. There are two solutions for this.
>     The first is to use jiffies_64 since s/390 is a 64-bit
>     architecture after all. The second is to use wrapper functions
>     like time_before and time_after. Two files were added too. 
>     They are: ctcm_main.c and netiucv.c. This patch could be sent
>     as a patchset in its final version for convenience. 
> 
>  drivers/s390/net/ctcm_fsms.c | 19 ++++++++-----------
>  drivers/s390/net/ctcm_main.c |  5 +++--
>  drivers/s390/net/ctcm_main.h |  4 +++-
>  drivers/s390/net/netiucv.c   |  8 +++++---
>  4 files changed, 19 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/s390/net/ctcm_fsms.c b/drivers/s390/net/ctcm_fsms.c
> index fb92524..86ed7bf 100644
> --- a/drivers/s390/net/ctcm_fsms.c
> +++ b/drivers/s390/net/ctcm_fsms.c
> @@ -23,6 +23,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/timer.h>
>  #include <linux/bitops.h>
> +#include <linux/jiffies.h>
> 
>  #include <linux/signal.h>
>  #include <linux/string.h>
> @@ -251,13 +252,11 @@ 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 =  jiffies_to_usecs(done_stamp - ch->prof.send_stamp);
>  	if (duration > ch->prof.tx_time)
>  		ch->prof.tx_time = duration;
> 
> @@ -307,7 +306,7 @@ 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 +1228,12 @@ 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 =  jiffies_to_usecs(done_stamp - ch->prof.send_stamp);
>  	if (duration > ch->prof.tx_time)
>  		ch->prof.tx_time = duration;
> 
> @@ -1361,7 +1358,7 @@ 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 +1824,7 @@ 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.c b/drivers/s390/net/ctcm_main.c
> index e056dd4..5dd68d9 100644
> --- a/drivers/s390/net/ctcm_main.c
> +++ b/drivers/s390/net/ctcm_main.c
> @@ -31,6 +31,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/timer.h>
>  #include <linux/bitops.h>
> +#include <linux/jiffies.h>
> 
>  #include <linux/signal.h>
>  #include <linux/string.h>
> @@ -567,7 +568,7 @@ static int ctcm_transmit_skb(struct channel *ch, struct sk_buff *skb)
>  	fsm_newstate(ch->fsm, CTC_STATE_TX);
>  	fsm_addtimer(&ch->timer, CTCM_TIME_5_SEC, CTC_EVENT_TIMER, ch);
>  	spin_lock_irqsave(get_ccwdev_lock(ch->cdev), saveflags);
> -	ch->prof.send_stamp = current_kernel_time(); /* xtime */
> +	ch->prof.send_stamp = jiffies;
>  	rc = ccw_device_start(ch->cdev, &ch->ccw[ccw_idx],
>  					(unsigned long)ch, 0xff, 0);
>  	spin_unlock_irqrestore(get_ccwdev_lock(ch->cdev), saveflags);
> @@ -831,7 +832,7 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb)
>  					sizeof(struct ccw1) * 3);
> 
>  	spin_lock_irqsave(get_ccwdev_lock(ch->cdev), saveflags);
> -	ch->prof.send_stamp = current_kernel_time(); /* xtime */
> +	ch->prof.send_stamp = jiffies;
>  	rc = ccw_device_start(ch->cdev, &ch->ccw[ccw_idx],
>  					(unsigned long)ch, 0xff, 0);
>  	spin_unlock_irqrestore(get_ccwdev_lock(ch->cdev), saveflags);
> diff --git a/drivers/s390/net/ctcm_main.h b/drivers/s390/net/ctcm_main.h
> index 477c933..c036e43 100644
> --- a/drivers/s390/net/ctcm_main.h
> +++ b/drivers/s390/net/ctcm_main.h
> @@ -10,6 +10,8 @@
>  #include <asm/ccwdev.h>
>  #include <asm/ccwgroup.h>
> 
> +#include <linux/jiffies.h>
> +
>  #include <linux/skbuff.h>
>  #include <linux/netdevice.h>
> 
> @@ -121,7 +123,7 @@ struct ctcm_profile {
>  	unsigned long doios_multi;
>  	unsigned long txlen;
>  	unsigned long tx_time;
> -	struct timespec send_stamp;
> +	unsigned long send_stamp;
>  };
> 
>  /*
> diff --git a/drivers/s390/net/netiucv.c b/drivers/s390/net/netiucv.c
> index 0a87809..5ea43fb 100644
> --- a/drivers/s390/net/netiucv.c
> +++ b/drivers/s390/net/netiucv.c
> @@ -49,6 +49,8 @@
>  #include <linux/interrupt.h>
>  #include <linux/timer.h>
>  #include <linux/bitops.h>
> +#include <linux/jiffies.h>
> +
> 
>  #include <linux/signal.h>
>  #include <linux/string.h>
> @@ -178,7 +180,7 @@ struct connection_profile {
>  	unsigned long doios_multi;
>  	unsigned long txlen;
>  	unsigned long tx_time;
> -	struct timespec send_stamp;
> +	unsigned long send_stamp;
>  	unsigned long tx_pending;
>  	unsigned long tx_max_pending;
>  };
> @@ -786,7 +788,7 @@ static void conn_action_txdone(fsm_instance *fi, int event, void *arg)
> 
>  	header.next = 0;
>  	memcpy(skb_put(conn->tx_buff, NETIUCV_HDRLEN), &header, NETIUCV_HDRLEN);
> -	conn->prof.send_stamp = current_kernel_time();
> +	conn->prof.send_stamp = jiffies;
>  	txmsg.class = 0;
>  	txmsg.tag = 0;
>  	rc = iucv_message_send(conn->path, &txmsg, 0, 0,
> @@ -1220,7 +1222,7 @@ static int netiucv_transmit_skb(struct iucv_connection *conn,
>  		memcpy(skb_put(nskb, NETIUCV_HDRLEN), &header,  NETIUCV_HDRLEN);
> 
>  		fsm_newstate(conn->fsm, CONN_STATE_TX);
> -		conn->prof.send_stamp = current_kernel_time();
> +		conn->prof.send_stamp = jiffies;
> 
>  		msg.tag = 1;
>  		msg.class = 0;


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