[OPW,kernel] drivers: s390: net: ctcm: migrate variables to handle y2038 problem
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Message ID 20141029160234.GA5003@localhost.localdomain
State New, archived
Headers show

Commit Message

Aya Mahfouz Oct. 29, 2014, 4:02 p.m. UTC
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.elyazal@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(-)

Comments

Ursula Braun Oct. 30, 2014, 9:03 a.m. UTC | #1
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.elyazal@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;
>  };
> 
>  /*

Patch
diff mbox

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;
 };
 
 /*