isdn: Use ktime_t instead of 'struct timeval'

'struct timeval' uses 32-bit representation for seconds which will
overflow in year 2038 and beyond. mISDN/clock.c needs to compute and
store elapsed time in intervals of 125 microseconds. This patch replaces
the usage of 'struct timeval' with 64-bit ktime_t which is y2038 safe.
The patch also replaces do_gettimeofday() (wall-clock time) with
ktime_get() (monotonic time) since we only care about elapsed time here.

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Suggested-by: Arnd Bergmnann <arnd@arndb.de>
Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/isdn/mISDN/clock.c b/drivers/isdn/mISDN/clock.c
index 693fb7c9b59a11591325e0a131091d34b2ac5dca..f8f659f1ce1b137a2e3b6f5693f6d015d4a9b0bd 100644 (file)
--- a/drivers/isdn/mISDN/clock.c
+++ b/drivers/isdn/mISDN/clock.c
@@ -37,6 +37,7 @@
 #include <linux/types.h>
 #include <linux/stddef.h>
 #include <linux/spinlock.h>
+#include <linux/ktime.h>
 #include <linux/mISDNif.h>
 #include <linux/export.h>
 #include "core.h"
@@ -45,15 +46,15 @@ static u_int *debug;
 static LIST_HEAD(iclock_list);
 static DEFINE_RWLOCK(iclock_lock);
 static u16 iclock_count;               /* counter of last clock */
-static struct timeval iclock_tv;       /* time stamp of last clock */
-static int iclock_tv_valid;            /* already received one timestamp */
+static ktime_t iclock_timestamp;       /* time stamp of last clock */
+static int iclock_timestamp_valid;     /* already received one timestamp */
 static struct mISDNclock *iclock_current;
 
 void
 mISDN_init_clock(u_int *dp)
 {
        debug = dp;
-       do_gettimeofday(&iclock_tv);
+       iclock_timestamp = ktime_get();
 }
 
 static void
@@ -86,7 +87,7 @@ select_iclock(void)
        }
        if (bestclock != iclock_current) {
                /* no clock received yet */
-               iclock_tv_valid = 0;
+               iclock_timestamp_valid = 0;
        }
        iclock_current = bestclock;
 }
@@ -139,12 +140,11 @@ mISDN_unregister_clock(struct mISDNclock *iclock)
 EXPORT_SYMBOL(mISDN_unregister_clock);
 
 void
-mISDN_clock_update(struct mISDNclock *iclock, int samples, struct timeval *tv)
+mISDN_clock_update(struct mISDNclock *iclock, int samples, ktime_t *timestamp)
 {
        u_long          flags;
-       struct timeval  tv_now;
-       time_t          elapsed_sec;
-       int             elapsed_8000th;
+       ktime_t         timestamp_now;
+       u16             delta;
 
        write_lock_irqsave(&iclock_lock, flags);
        if (iclock_current != iclock) {
@@ -156,33 +156,27 @@ mISDN_clock_update(struct mISDNclock *iclock, int samples, struct timeval *tv)
                write_unlock_irqrestore(&iclock_lock, flags);
                return;
        }
-       if (iclock_tv_valid) {
+       if (iclock_timestamp_valid) {
                /* increment sample counter by given samples */
                iclock_count += samples;
-               if (tv) { /* tv must be set, if function call is delayed */
-                       iclock_tv.tv_sec = tv->tv_sec;
-                       iclock_tv.tv_usec = tv->tv_usec;
-               } else
-                       do_gettimeofday(&iclock_tv);
+               if (timestamp) { /* timestamp must be set, if function call is delayed */
+                       iclock_timestamp = *timestamp;
+               } else  {
+                       iclock_timestamp = ktime_get();
+               }
        } else {
                /* calc elapsed time by system clock */
-               if (tv) { /* tv must be set, if function call is delayed */
-                       tv_now.tv_sec = tv->tv_sec;
-                       tv_now.tv_usec = tv->tv_usec;
-               } else
-                       do_gettimeofday(&tv_now);
-               elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
-               elapsed_8000th = (tv_now.tv_usec / 125)
-                       - (iclock_tv.tv_usec / 125);
-               if (elapsed_8000th < 0) {
-                       elapsed_sec -= 1;
-                       elapsed_8000th += 8000;
+               if (timestamp) { /* timestamp must be set, if function call is delayed */
+                       timestamp_now = *timestamp;
+               } else {
+                       timestamp_now = ktime_get();
                }
+               delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp),
+                               (NSEC_PER_SEC / 8000));
                /* add elapsed time to counter and set new timestamp */
-               iclock_count += elapsed_sec * 8000 + elapsed_8000th;
-               iclock_tv.tv_sec = tv_now.tv_sec;
-               iclock_tv.tv_usec = tv_now.tv_usec;
-               iclock_tv_valid = 1;
+               iclock_count += delta;
+               iclock_timestamp = timestamp_now;
+               iclock_timestamp_valid = 1;
                if (*debug & DEBUG_CLOCK)
                        printk("Received first clock from source '%s'.\n",
                               iclock_current ? iclock_current->name : "nothing");
@@ -195,22 +189,17 @@ unsigned short
 mISDN_clock_get(void)
 {
        u_long          flags;
-       struct timeval  tv_now;
-       time_t          elapsed_sec;
-       int             elapsed_8000th;
+       ktime_t         timestamp_now;
+       u16             delta;
        u16             count;
 
        read_lock_irqsave(&iclock_lock, flags);
        /* calc elapsed time by system clock */
-       do_gettimeofday(&tv_now);
-       elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
-       elapsed_8000th = (tv_now.tv_usec / 125) - (iclock_tv.tv_usec / 125);
-       if (elapsed_8000th < 0) {
-               elapsed_sec -= 1;
-               elapsed_8000th += 8000;
-       }
+       timestamp_now = ktime_get();
+       delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp),
+                       (NSEC_PER_SEC / 8000));
        /* add elapsed time to counter */
-       count = iclock_count + elapsed_sec * 8000 + elapsed_8000th;
+       count = iclock_count + delta;
        read_unlock_irqrestore(&iclock_lock, flags);
        return count;
 }

diff --git a/include/linux/mISDNif.h b/include/linux/mISDNif.h
index 246a3529ecf644d67d3036d823a7c89ad0881f06..ac02c54520e9733096ec984f3efe98b909182bfd 100644 (file)
--- a/include/linux/mISDNif.h
+++ b/include/linux/mISDNif.h
@@ -596,7 +596,7 @@ static inline struct mISDNdevice *dev_to_mISDN(struct device *dev)
 }
 
 extern void    set_channel_address(struct mISDNchannel *, u_int, u_int);
-extern void    mISDN_clock_update(struct mISDNclock *, int, struct timeval *);
+extern void    mISDN_clock_update(struct mISDNclock *, int, ktime_t *);
 extern unsigned short mISDN_clock_get(void);
 extern const char *mISDNDevName4ch(struct mISDNchannel *);