Apr 16 2008

V4L/DVB (7591): drivers/media/video: use time_before, time_before_eq, etc 

Author: Julia Lawall <julia@diku.dk>

The functions time_before, time_before_eq, time_after, and time_after_eq
are more robust for comparing jiffies against other values.

A simplified version of the semantic patch making this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// 
@ change_compare_np @
expression E;
@@

(
- jiffies <= E
+ time_before_eq(jiffies,E)
|
- jiffies >= E
+ time_after_eq(jiffies,E)
|
- jiffies < E
+ time_before(jiffies,E)
|
- jiffies > E
+ time_after(jiffies,E)
)

@ include depends on change_compare_np @
@@

@ no_include depends on !include && change_compare_np @
@@

  #include 
+ #include 
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Andrew Morton 
Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab 

---
 drivers/media/video/c-qcam.c            |  7 +++++--
 drivers/media/video/ivtv/ivtv-fileops.c |  4 +++-
 drivers/media/video/ivtv/ivtv-mailbox.c | 11 +++++++----
 drivers/media/video/ivtv/ivtv-streams.c |  3 ++-
 4 files changed, 17 insertions(+), 8 deletions(-)
 
diff --git a/drivers/media/video/c-qcam.c b/drivers/media/video/c-qcam.c
index 2c85ced..fe1e67b 100644
--- a/drivers/media/video/c-qcam.c
+++ b/drivers/media/video/c-qcam.c
@@ -36,6 +36,7 @@
 #include <linux/videodev.h>
 #include <media/v4l2-common.h>
 #include <linux/mutex.h>
+#include <linux/jiffies.h>
 
 #include <asm/uaccess.h>
 
@@ -95,7 +96,8 @@ static unsigned int qcam_await_ready1(struct qcam_device *qcam,
 	unsigned long oldjiffies = jiffies;
 	unsigned int i;
 
-	for (oldjiffies = jiffies; (jiffies - oldjiffies) < msecs_to_jiffies(40); )
+	for (oldjiffies = jiffies;
+	     time_before(jiffies, oldjiffies + msecs_to_jiffies(40)); )
 		if (qcam_ready1(qcam) == value)
 			return 0;
 
@@ -120,7 +122,8 @@ static unsigned int qcam_await_ready2(struct qcam_device *qcam, int value)
 	unsigned long oldjiffies = jiffies;
 	unsigned int i;
 
-	for (oldjiffies = jiffies; (jiffies - oldjiffies) < msecs_to_jiffies(40); )
+	for (oldjiffies = jiffies;
+	     time_before(jiffies, oldjiffies + msecs_to_jiffies(40)); )
 		if (qcam_ready2(qcam) == value)
 			return 0;
 
diff --git a/drivers/media/video/ivtv/ivtv-fileops.c b/drivers/media/video/ivtv/ivtv-fileops.c
index d949a81..a7640c4 100644
--- a/drivers/media/video/ivtv/ivtv-fileops.c
+++ b/drivers/media/video/ivtv/ivtv-fileops.c
@@ -219,7 +219,9 @@ static struct ivtv_buffer *ivtv_get_buffer(struct ivtv_stream *s, int non_block,
 			/* Process pending program info updates and pending VBI data */
 			ivtv_update_pgm_info(itv);
 
-			if (jiffies - itv->dualwatch_jiffies > msecs_to_jiffies(1000)) {
+			if (time_after(jiffies,
+				       itv->dualwatch_jiffies +
+				       msecs_to_jiffies(1000))) {
 				itv->dualwatch_jiffies = jiffies;
 				ivtv_dualwatch(itv);
 			}
diff --git a/drivers/media/video/ivtv/ivtv-mailbox.c b/drivers/media/video/ivtv/ivtv-mailbox.c
index 13a6c37..1b5c0ac 100644
--- a/drivers/media/video/ivtv/ivtv-mailbox.c
+++ b/drivers/media/video/ivtv/ivtv-mailbox.c
@@ -177,7 +177,8 @@ static int get_mailbox(struct ivtv *itv, struct ivtv_mailbox_data *mbdata, int f
 
 		/* Sleep before a retry, if not atomic */
 		if (!(flags & API_NO_WAIT_MB)) {
-			if (jiffies - then > msecs_to_jiffies(10*retries))
+			if (time_after(jiffies,
+				       then + msecs_to_jiffies(10*retries)))
 			       break;
 			ivtv_msleep_timeout(10, 0);
 		}
@@ -244,7 +245,9 @@ static int ivtv_api_call(struct ivtv *itv, int cmd, int args, u32 data[])
 	   data, then just return 0 as there is no need to issue this command again.
 	   Just an optimization to prevent unnecessary use of mailboxes. */
 	if (itv->api_cache[cmd].last_jiffies &&
-	    jiffies - itv->api_cache[cmd].last_jiffies < msecs_to_jiffies(1800000) &&
+	    time_before(jiffies,
+			itv->api_cache[cmd].last_jiffies +
+			msecs_to_jiffies(1800000)) &&
 	    !memcmp(data, itv->api_cache[cmd].data, sizeof(itv->api_cache[cmd].data))) {
 		itv->api_cache[cmd].last_jiffies = jiffies;
 		return 0;
@@ -299,7 +302,7 @@ static int ivtv_api_call(struct ivtv *itv, int cmd, int args, u32 data[])
 		}
 	}
 	while (!(readl(&mbox->flags) & IVTV_MBOX_FIRMWARE_DONE)) {
-		if (jiffies - then > api_timeout) {
+		if (time_after(jiffies, then + api_timeout)) {
 			IVTV_DEBUG_WARN("Could not get result (%s)\n", api_info[cmd].name);
 			/* reset the mailbox, but it is likely too late already */
 			write_sync(0, &mbox->flags);
@@ -311,7 +314,7 @@ static int ivtv_api_call(struct ivtv *itv, int cmd, int args, u32 data[])
 		else
 			ivtv_msleep_timeout(1, 0);
 	}
-	if (jiffies - then > msecs_to_jiffies(100))
+	if (time_after(jiffies, then + msecs_to_jiffies(100)))
 		IVTV_DEBUG_WARN("%s took %u jiffies\n",
 				api_info[cmd].name,
 				jiffies_to_msecs(jiffies - then));
diff --git a/drivers/media/video/ivtv/ivtv-streams.c b/drivers/media/video/ivtv/ivtv-streams.c
index 24d98ec..4ab8d36 100644
--- a/drivers/media/video/ivtv/ivtv-streams.c
+++ b/drivers/media/video/ivtv/ivtv-streams.c
@@ -768,7 +768,8 @@ int ivtv_stop_v4l2_encode_stream(struct ivtv_stream *s, int gop_end)
 
 			/* wait 2s for EOS interrupt */
 			while (!test_bit(IVTV_F_I_EOS, &itv->i_flags) &&
-				jiffies < then + msecs_to_jiffies (2000)) {
+				time_before(jiffies,
+					    then + msecs_to_jiffies(2000))) {
 				schedule_timeout(msecs_to_jiffies(10));
 			}

qlambert