[PATCH 5.5 38/46] rxrpc: Fix sendmsg(MSG_WAITALL) handling

From: Greg Kroah-Hartman
Date: Tue Apr 07 2020 - 06:28:33 EST


From: David Howells <dhowells@xxxxxxxxxx>

commit 498b577660f08cef5d9e78e0ed6dcd4c0939e98c upstream.

Fix the handling of sendmsg() with MSG_WAITALL for userspace to round the
timeout for when a signal occurs up to at least two jiffies as a 1 jiffy
timeout may end up being effectively 0 if jiffies wraps at the wrong time.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/rxrpc/sendmsg.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -58,8 +58,8 @@ static int rxrpc_wait_for_tx_window_wait

rtt = READ_ONCE(call->peer->rtt);
rtt2 = nsecs_to_jiffies64(rtt) * 2;
- if (rtt2 < 1)
- rtt2 = 1;
+ if (rtt2 < 2)
+ rtt2 = 2;

timeout = rtt2;
tx_start = READ_ONCE(call->tx_hard_ack);