[PATCH net-next 11/14] rxrpc: Fix retransmission algorithm

[David Howells]

Make the retransmission algorithm use for-loops instead of do-loops and
move the counter increments into the for-statement increment slots.

Though the do-loops are slighly more efficient since there will be at least
one pass through the each loop, the counter increments are harder to get
right as the continue-statements skip them.

Without this, if there are any positive acks within the loop, the do-loop
will cycle forever because the counter increment is never done.

Signed-off-by: David Howells <dhowe...@redhat.com>
---

 net/rxrpc/call_event.c |   12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 9367c3be31eb..f0cabc48a1b7 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -163,8 +163,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
         */
        now = jiffies;
        resend_at = now + rxrpc_resend_timeout;
-       seq = cursor + 1;
-       do {
+       for (seq = cursor + 1; before_eq(seq, top); seq++) {
                ix = seq & RXRPC_RXTX_BUFF_MASK;
                annotation = call->rxtx_annotations[ix];
                if (annotation == RXRPC_TX_ANNO_ACK)
@@ -184,8 +183,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
 
                /* Okay, we need to retransmit a packet. */
                call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS;
-               seq++;
-       } while (before_eq(seq, top));
+       }
 
        call->resend_at = resend_at;
 
@@ -194,8 +192,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
         * lock is dropped, it may clear some of the retransmission markers for
         * packets that it soft-ACKs.
         */
-       seq = cursor + 1;
-       do {
+       for (seq = cursor + 1; before_eq(seq, top); seq++) {
                ix = seq & RXRPC_RXTX_BUFF_MASK;
                annotation = call->rxtx_annotations[ix];
                if (annotation != RXRPC_TX_ANNO_RETRANS)
@@ -237,8 +234,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
 
                if (after(call->tx_hard_ack, seq))
                        seq = call->tx_hard_ack;
-               seq++;
-       } while (before_eq(seq, top));
+       }
 
 out_unlock:
        spin_unlock_bh(&call->lock);