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Groups > linux.kernel > #1485633

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

From David Howells <dhowells@redhat.com>
Newsgroups linux.kernel
Subject [PATCH net-next 11/14] rxrpc: Fix retransmission algorithm
Date 2016-09-18 01:30 +0200
Message-ID <sixdw-qm-5@gated-at.bofh.it> (permalink)
References <six3P-mU-3@gated-at.bofh.it>
Organization Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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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 <dhowells@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);

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Thread

[PATCH net-next 00/14] rxrpc: Fixes & miscellany David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 09/14] rxrpc: Fix unexposed client conn release David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 12/14] rxrpc: Don't transmit an ACK if there's no  reason set David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 07/14] rxrpc: Fix the putting of client connections David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 14/14] rxrpc: Fix the basic transmit DATA packet  content size at 1412 bytes David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 06/14] rxrpc: Purge the to_be_accepted queue on  socket release David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 01/14] rxrpc: Remove some whitespace. David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 03/14] rxrpc: Check the return value of  rxrpc_locate_data() David Howells <dhowells@redhat.com> - 2016-09-18 01:20 +0200
  [PATCH net-next 11/14] rxrpc: Fix retransmission algorithm David Howells <dhowells@redhat.com> - 2016-09-18 01:30 +0200
  [PATCH net-next 05/14] rxrpc: Record calls that need to be accepted David Howells <dhowells@redhat.com> - 2016-09-18 01:30 +0200
  [PATCH net-next 13/14] rxrpc: Be consistent about switch value in  rxrpc_send_call_packet() David Howells <dhowells@redhat.com> - 2016-09-18 01:30 +0200
  [PATCH net-next 02/14] rxrpc: Move the check of rx_pkt_offset from  rxrpc_locate_data() to caller David Howells <dhowells@redhat.com> - 2016-09-18 01:30 +0200
  [PATCH net-next 10/14] rxrpc: Fix the parsing of soft-ACKs David Howells <dhowells@redhat.com> - 2016-09-18 01:30 +0200
  Re: [PATCH net-next 00/14] rxrpc: Fixes & miscellany David Miller <davem@davemloft.net> - 2016-09-18 13:30 +0200
  Re: [PATCH net-next 00/14] rxrpc: Fixes & miscellany David Miller <davem@davemloft.net> - 2016-09-19 08:00 +0200

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