[PATCH v3] [media] dvb-frontend: Replace timeval with ktime_t

Tina Ruchandani
2015-05-31T07:17:19Z

struct timeval uses a 32-bit seconds representation which will
overflow in the year 2038 and beyond. This patch replaces
the usage of struct timeval with ktime_t which is a 64-bit
timestamp and is year 2038 safe.
This patch is part of a larger attempt to remove all instances
of 32-bit timekeeping variables (timeval, timespec, time_t)
which are not year 2038 safe, from the kernel.

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Suggested-by: Arnd Bergmann <arndb@arndb.de>

--
Changes in v3:
- Clean up commit message.
- Use ktime_us_delta which is more concise than the combination
of ktime_sub and ktime_to_us
Changes in v2:
- Use the more concise ktime_us_delta
- Preserve the waketime argument in dvb_frontend_sleep_until as
a pointer, fixes bug introduced in v1 of the patch where the caller
doesn't get its timestamp modified.

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
---
drivers/media/dvb-core/dvb_frontend.c | 41 ++++++++++-------------------------
drivers/media/dvb-core/dvb_frontend.h | 3 +--
drivers/media/dvb-frontends/stv0299.c | 12 +++++-----
3 files changed, 19 insertions(+), 37 deletions(-)

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index 882ca41..69be73c 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -40,6 +40,7 @@
#include <linux/freezer.h>
#include <linux/jiffies.h>
#include <linux/kthread.h>
+#include <linux/ktime.h>
#include <asm/processor.h>

#include "dvb_frontend.h"
@@ -889,42 +890,21 @@ static void dvb_frontend_stop(struct dvb_frontend *fe)
fepriv->thread);
}

-s32 timeval_usec_diff(struct timeval lasttime, struct timeval curtime)
-{
- return ((curtime.tv_usec < lasttime.tv_usec) ?
- 1000000 - lasttime.tv_usec + curtime.tv_usec :
- curtime.tv_usec - lasttime.tv_usec);
-}
-EXPORT_SYMBOL(timeval_usec_diff);
-
-static inline void timeval_usec_add(struct timeval *curtime, u32 add_usec)
-{
- curtime->tv_usec += add_usec;
- if (curtime->tv_usec >= 1000000) {
- curtime->tv_usec -= 1000000;
- curtime->tv_sec++;
- }
-}
-
/*
* Sleep until gettimeofday() > waketime + add_usec
* This needs to be as precise as possible, but as the delay is
* usually between 2ms and 32ms, it is done using a scheduled msleep
* followed by usleep (normally a busy-wait loop) for the remainder
*/
-void dvb_frontend_sleep_until(struct timeval *waketime, u32 add_usec)
+void dvb_frontend_sleep_until(ktime_t *waketime, u32 add_usec)
{
- struct timeval lasttime;
s32 delta, newdelta;

- timeval_usec_add(waketime, add_usec);
-
- do_gettimeofday(&lasttime);
- delta = timeval_usec_diff(lasttime, *waketime);
+ ktime_add_us(*waketime, add_usec);
+ delta = ktime_us_delta(ktime_get_real(), *waketime);
if (delta > 2500) {
msleep((delta - 1500) / 1000);
- do_gettimeofday(&lasttime);
- newdelta = timeval_usec_diff(lasttime, *waketime);
+ newdelta = ktime_us_delta(ktime_get_real(), *waketime);
delta = (newdelta > delta) ? 0 : newdelta;
}
if (delta > 0)
@@ -2458,13 +2438,13 @@ static int dvb_frontend_ioctl_legacy(struct file *file,
* include the initialization or start bit
*/
unsigned long swcmd = ((unsigned long) parg) << 1;
- struct timeval nexttime;
- struct timeval tv[10];
+ ktime_t nexttime;
+ ktime_t tv[10];
int i;
u8 last = 1;
if (dvb_frontend_debug)
printk("%s switch command: 0x%04lx\n", __func__, swcmd);
- do_gettimeofday(&nexttime);
+ nexttime = ktime_get_real();
if (dvb_frontend_debug)
tv[0] = nexttime;
/* before sending a command, initialize by sending
@@ -2475,7 +2455,7 @@ static int dvb_frontend_ioctl_legacy(struct file *file,

for (i = 0; i < 9; i++) {
if (dvb_frontend_debug)
- do_gettimeofday(&tv[i + 1]);
+ tv[i+1] = ktime_get_real();
if ((swcmd & 0x01) != last) {
/* set voltage to (last ? 13V : 18V) */
fe->ops.set_voltage(fe, (last) ? SEC_VOLTAGE_13 : SEC_VOLTAGE_18);
@@ -2489,7 +2469,8 @@ static int dvb_frontend_ioctl_legacy(struct file *file,
printk("%s(%d): switch delay (should be 32k followed by all 8k\n",
__func__, fe->dvb->num);
for (i = 1; i < 10; i++)
- printk("%d: %d\n", i, timeval_usec_diff(tv[i-1] , tv[i]));
+ printk("%d: %d\n", i,
+ (int) ktime_us_delta(tv[i], tv[i-1]);
}
err = 0;
fepriv->state = FESTATE_DISEQC;
diff --git a/drivers/media/dvb-core/dvb_frontend.h b/drivers/media/dvb-core/dvb_frontend.h
index 816269e..5b64686 100644
--- a/drivers/media/dvb-core/dvb_frontend.h
+++ b/drivers/media/dvb-core/dvb_frontend.h
@@ -439,7 +439,6 @@ extern void dvb_frontend_reinitialise(struct dvb_frontend *fe);
extern int dvb_frontend_suspend(struct dvb_frontend *fe);
extern int dvb_frontend_resume(struct dvb_frontend *fe);

-extern void dvb_frontend_sleep_until(struct timeval *waketime, u32 add_usec);
-extern s32 timeval_usec_diff(struct timeval lasttime, struct timeval curtime);
+extern void dvb_frontend_sleep_until(ktime_t *waketime, u32 add_usec);

#endif
diff --git a/drivers/media/dvb-frontends/stv0299.c b/drivers/media/dvb-frontends/stv0299.c
index b57ecf4..347c2bc 100644
--- a/drivers/media/dvb-frontends/stv0299.c
+++ b/drivers/media/dvb-frontends/stv0299.c
@@ -44,6 +44,7 @@

#include <linux/init.h>
#include <linux/kernel.h>
+#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/slab.h>
@@ -404,8 +405,8 @@ static int stv0299_send_legacy_dish_cmd (struct dvb_frontend* fe, unsigned long
u8 lv_mask = 0x40;
u8 last = 1;
int i;
- struct timeval nexttime;
- struct timeval tv[10];
+ ktime_t nexttime;
+ ktime_t tv[10];

reg0x08 = stv0299_readreg (state, 0x08);
reg0x0c = stv0299_readreg (state, 0x0c);
@@ -418,7 +419,7 @@ static int stv0299_send_legacy_dish_cmd (struct dvb_frontend* fe, unsigned long
if (debug_legacy_dish_switch)
printk ("%s switch command: 0x%04lx\n",__func__, cmd);

- do_gettimeofday (&nexttime);
+ nexttime = ktime_get_real();
if (debug_legacy_dish_switch)
tv[0] = nexttime;
stv0299_writeregI (state, 0x0c, reg0x0c | 0x50); /* set LNB to 18V */
@@ -427,7 +428,7 @@ static int stv0299_send_legacy_dish_cmd (struct dvb_frontend* fe, unsigned long

for (i=0; i<9; i++) {
if (debug_legacy_dish_switch)
- do_gettimeofday (&tv[i+1]);
+ tv[i+1] = ktime_get_real();
if((cmd & 0x01) != last) {
/* set voltage to (last ? 13V : 18V) */
stv0299_writeregI (state, 0x0c, reg0x0c | (last ? lv_mask : 0x50));
@@ -443,7 +444,8 @@ static int stv0299_send_legacy_dish_cmd (struct dvb_frontend* fe, unsigned long
printk ("%s(%d): switch delay (should be 32k followed by all 8k\n",
__func__, fe->dvb->num);
for (i = 1; i < 10; i++)
- printk ("%d: %d\n", i, timeval_usec_diff(tv[i-1] , tv[i]));
+ printk("%d: %d\n", i,
+ (int) ktime_us_delta(tv[i], tv[i-1]));
}

return 0;
--
2.2.0.rc0.207.ga3a616c