[PATCH 4.16 094/272] rxrpc: Fix resend event time calculation

Greg Kroah-Hartman
2018-05-28T11:57:19Z

From: Marc Dionne <marc.dionne@auristor.com>

[ Upstream commit 59299aa1028fce051adbd25aaff7c387b865cd6d ]

Commit a158bdd3 ("rxrpc: Fix call timeouts") reworked the time calculation
for the next resend event. For this calculation, "oldest" will be before
"now", so ktime_sub(oldest, now) will yield a negative value. When passed
to nsecs_to_jiffies which expects an unsigned value, the end result will be
a very large value, and a resend event scheduled far into the future. This
could cause calls to stall if some packets were lost.

Fix by ordering the arguments to ktime_sub correctly.

Fixes: a158bdd3247b ("rxrpc: Fix call timeouts")
Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/rxrpc/call_event.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -225,7 +225,7 @@ static void rxrpc_resend(struct rxrpc_ca
ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
}

- resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(oldest, now)));
+ resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
resend_at += jiffies + rxrpc_resend_timeout;
WRITE_ONCE(call->resend_at, resend_at);