From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: [RFC] irda: irttp: allow zero byte packets Date: Wed, 10 Nov 2010 00:19:47 +0100 Message-ID: <1289344787-12160-1-git-send-email-w.sang@pengutronix.de> Cc: netdev@vger.kernel.org, Wolfram Sang , Samuel Ortiz To: irda-users@lists.sourceforge.net Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:55867 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753483Ab0KIXTo (ORCPT ); Tue, 9 Nov 2010 18:19:44 -0500 Sender: netdev-owner@vger.kernel.org List-ID: Sending zero byte packets is not neccessarily an error (AF_INET accepts it, too), so just apply a shortcut. This was discovered because of a non-working software with WINE. See http://bugs.winehq.org/show_bug.cgi?id=19397#c86 http://thread.gmane.org/gmane.linux.irda.general/1643 for very detailed debugging information and a testcase. Kudos to Wolfgang for those! Reported-by: Wolfgang Schwotzer Signed-off-by: Wolfram Sang Tested-by: Mike Evans Cc: Samuel Ortiz --- I found Wolfgang's very detailed report while looking for WINE-bugreports affecting the kernel somehow. His mail sadly went to an almost dead mailing-list and he told me he lost interest meanwhile. This is why I picked the issue up and created this straightforward patch which helps the case at least (thanks Mike for testing!). net/irda/irttp.c | 25 +++++++++++++++++++------ 1 files changed, 19 insertions(+), 6 deletions(-) diff --git a/net/irda/irttp.c b/net/irda/irttp.c index 285761e..6cfaeaf 100644 --- a/net/irda/irttp.c +++ b/net/irda/irttp.c @@ -550,16 +550,23 @@ EXPORT_SYMBOL(irttp_close_tsap); */ int irttp_udata_request(struct tsap_cb *self, struct sk_buff *skb) { + int ret = -1; + IRDA_ASSERT(self != NULL, return -1;); IRDA_ASSERT(self->magic == TTP_TSAP_MAGIC, return -1;); IRDA_ASSERT(skb != NULL, return -1;); IRDA_DEBUG(4, "%s()\n", __func__); + /* Take shortcut on zero byte packets */ + if (skb->len == 0) { + ret = 0; + goto err; + } + /* Check that nothing bad happens */ - if ((skb->len == 0) || (!self->connected)) { - IRDA_DEBUG(1, "%s(), No data, or not connected\n", - __func__); + if (!self->connected) { + IRDA_DEBUG(1, "%s(), Not connected\n", __func__); goto err; } @@ -576,7 +583,7 @@ int irttp_udata_request(struct tsap_cb *self, struct sk_buff *skb) err: dev_kfree_skb(skb); - return -1; + return ret; } EXPORT_SYMBOL(irttp_udata_request); @@ -599,9 +606,15 @@ int irttp_data_request(struct tsap_cb *self, struct sk_buff *skb) IRDA_DEBUG(2, "%s() : queue len = %d\n", __func__, skb_queue_len(&self->tx_queue)); + /* Take shortcut on zero byte packets */ + if (skb->len == 0) { + ret = 0; + goto err; + } + /* Check that nothing bad happens */ - if ((skb->len == 0) || (!self->connected)) { - IRDA_WARNING("%s: No data, or not connected\n", __func__); + if (!self->connected) { + IRDA_WARNING("%s: Not connected\n", __func__); ret = -ENOTCONN; goto err; } -- 1.7.2.3