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Subject[PATCH v3] [media] dvb: use ktime_t for internal timeout
Date
The dvb demuxer code uses a 'struct timespec' to pass a timeout
as absolute time. This will cause problems on 32-bit architectures
in 2038 when time_t overflows, and it is racy with a concurrent
settimeofday() call.

This patch changes the code to use ktime_get() instead, using
the monotonic time base to avoid both the race and the overflow.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I originally submitted this last year along with some other patches that
did not make it and that we have to write again from scratch at some point,
but for all I know, this one could just get applied independently for 4.8.

diff --git a/drivers/media/dvb-core/demux.h b/drivers/media/dvb-core/demux.h
index 6d3b95b8939d..7f1dffef4353 100644
--- a/drivers/media/dvb-core/demux.h
+++ b/drivers/media/dvb-core/demux.h
@@ -143,7 +143,7 @@ struct dmx_ts_feed {
int type,
enum dmx_ts_pes pes_type,
size_t circular_buffer_size,
- struct timespec timeout);
+ ktime_t timeout);
int (*start_filtering)(struct dmx_ts_feed *feed);
int (*stop_filtering)(struct dmx_ts_feed *feed);
};
diff --git a/drivers/media/dvb-core/dmxdev.c b/drivers/media/dvb-core/dmxdev.c
index a168cbe1c998..7b67e1dd97fd 100644
--- a/drivers/media/dvb-core/dmxdev.c
+++ b/drivers/media/dvb-core/dmxdev.c
@@ -556,7 +556,7 @@ static int dvb_dmxdev_start_feed(struct dmxdev *dmxdev,
struct dmxdev_filter *filter,
struct dmxdev_feed *feed)
{
- struct timespec timeout = { 0 };
+ ktime_t timeout = ktime_set(0, 0);
struct dmx_pes_filter_params *para = &filter->params.pes;
dmx_output_t otype;
int ret;
diff --git a/drivers/media/dvb-core/dvb_demux.c b/drivers/media/dvb-core/dvb_demux.c
index 0cc5e935166c..a0cf7b0d03e8 100644
--- a/drivers/media/dvb-core/dvb_demux.c
+++ b/drivers/media/dvb-core/dvb_demux.c
@@ -398,28 +398,23 @@ static void dvb_dmx_swfilter_packet(struct dvb_demux *demux, const u8 *buf)
int dvr_done = 0;

if (dvb_demux_speedcheck) {
- struct timespec cur_time, delta_time;
+ ktime_t cur_time;
u64 speed_bytes, speed_timedelta;

demux->speed_pkts_cnt++;

/* show speed every SPEED_PKTS_INTERVAL packets */
if (!(demux->speed_pkts_cnt % SPEED_PKTS_INTERVAL)) {
- cur_time = current_kernel_time();
+ cur_time = ktime_get();

- if (demux->speed_last_time.tv_sec != 0 &&
- demux->speed_last_time.tv_nsec != 0) {
- delta_time = timespec_sub(cur_time,
- demux->speed_last_time);
+ if (ktime_to_ns(demux->speed_last_time) != 0) {
speed_bytes = (u64)demux->speed_pkts_cnt
* 188 * 8;
/* convert to 1024 basis */
speed_bytes = 1000 * div64_u64(speed_bytes,
1024);
- speed_timedelta =
- (u64)timespec_to_ns(&delta_time);
- speed_timedelta = div64_u64(speed_timedelta,
- 1000000); /* nsec -> usec */
+ speed_timedelta = ktime_ms_delta(cur_time,
+ demux->speed_last_time);
printk(KERN_INFO "TS speed %llu Kbits/sec \n",
div64_u64(speed_bytes,
speed_timedelta));
@@ -666,7 +661,7 @@ out:

static int dmx_ts_feed_set(struct dmx_ts_feed *ts_feed, u16 pid, int ts_type,
enum dmx_ts_pes pes_type,
- size_t circular_buffer_size, struct timespec timeout)
+ size_t circular_buffer_size, ktime_t timeout)
{
struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed;
struct dvb_demux *demux = feed->demux;
diff --git a/drivers/media/dvb-core/dvb_demux.h b/drivers/media/dvb-core/dvb_demux.h
index ae7fc33c3231..5ed3cab4ad28 100644
--- a/drivers/media/dvb-core/dvb_demux.h
+++ b/drivers/media/dvb-core/dvb_demux.h
@@ -83,7 +83,7 @@ struct dvb_demux_feed {
u8 *buffer;
int buffer_size;

- struct timespec timeout;
+ ktime_t timeout;
struct dvb_demux_filter *filter;

int ts_type;
@@ -134,7 +134,7 @@ struct dvb_demux {

uint8_t *cnt_storage; /* for TS continuity check */

- struct timespec speed_last_time; /* for TS speed check */
+ ktime_t speed_last_time; /* for TS speed check */
uint32_t speed_pkts_cnt; /* for TS speed check */
};

diff --git a/drivers/media/dvb-core/dvb_net.c b/drivers/media/dvb-core/dvb_net.c
index ce6a711b42d4..9914f69a4a02 100644
--- a/drivers/media/dvb-core/dvb_net.c
+++ b/drivers/media/dvb-core/dvb_net.c
@@ -997,7 +997,7 @@ static int dvb_net_feed_start(struct net_device *dev)
netdev_dbg(dev, "start filtering\n");
priv->secfeed->start_filtering(priv->secfeed);
} else if (priv->feedtype == DVB_NET_FEEDTYPE_ULE) {
- struct timespec timeout = { 0, 10000000 }; // 10 msec
+ ktime_t timeout = ns_to_ktime(10 * NSEC_PER_MSEC);

/* we have payloads encapsulated in TS */
netdev_dbg(dev, "alloc tsfeed\n");
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