[PATCH 5.6 016/177] net sched: fix reporting the first-time use timestamp

[Greg Kroah-Hartman]

From: Roman Mashak <mrv@xxxxxxxxxxxx>

[ Upstream commit b15e62631c5f19fea9895f7632dae9c1b27fe0cd ]

When a new action is installed, firstuse field of 'tcf_t' is explicitly set
to 0. Value of zero means "new action, not yet used"; as a packet hits the
action, 'firstuse' is stamped with the current jiffies value.

tcf_tm_dump() should return 0 for firstuse if action has not yet been hit.

Fixes: 48d8ee1694dd ("net sched actions: aggregate dumping of actions timeinfo")
Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: Roman Mashak <mrv@xxxxxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/net/act_api.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -69,7 +69,8 @@ static inline void tcf_tm_dump(struct tc
 {
 	dtm->install = jiffies_to_clock_t(jiffies - stm->install);
 	dtm->lastuse = jiffies_to_clock_t(jiffies - stm->lastuse);
-	dtm->firstuse = jiffies_to_clock_t(jiffies - stm->firstuse);
+	dtm->firstuse = stm->firstuse ?
+		jiffies_to_clock_t(jiffies - stm->firstuse) : 0;
 	dtm->expires = jiffies_to_clock_t(stm->expires);
 }