From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:52560 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751811AbeB0R6r (ORCPT ); Tue, 27 Feb 2018 12:58:47 -0500 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1RHw4xP005329 for ; Tue, 27 Feb 2018 12:58:47 -0500 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2gdc01gf6d-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 27 Feb 2018 12:58:46 -0500 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 27 Feb 2018 17:58:34 -0000 From: Julian Wiedmann To: David Miller Cc: , , Martin Schwidefsky , Heiko Carstens , Stefan Raspl , Ursula Braun , Julian Wiedmann Subject: [PATCH net 6/6] s390/qeth: fix IPA command submission race Date: Tue, 27 Feb 2018 18:58:17 +0100 In-Reply-To: <20180227175817.84727-1-jwi@linux.vnet.ibm.com> References: <20180227175817.84727-1-jwi@linux.vnet.ibm.com> Message-Id: <20180227175817.84727-7-jwi@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: If multiple IPA commands are build & sent out concurrently, fill_ipacmd_header() may assign a seqno value to a command that's different from what send_control_data() later assigns to this command's reply. This is due to other commands passing through send_control_data(), and incrementing card->seqno.ipa along the way. So one IPA command has no reply that's waiting for its seqno, while some other IPA command has multiple reply objects waiting for it. Only one of those waiting replies wins, and the other(s) times out and triggers a recovery via send_ipa_cmd(). Fix this by making sure that the same seqno value is assigned to a command and its reply object. Do so immediately before submitting the command & while holding the irq_pending "lock", to produce nicely ascending seqnos. As a side effect, *all* IPA commands now use a reply object that's waiting for its actual seqno. Previously, early IPA commands that were submitted while the card was still DOWN used the "catch-all" IDX seqno. Signed-off-by: Julian Wiedmann --- drivers/s390/net/qeth_core_main.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index 30457fca30c5..c8b308cfabf1 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -2134,24 +2134,25 @@ int qeth_send_control_data(struct qeth_card *card, int len, } reply->callback = reply_cb; reply->param = reply_param; - if (card->state == CARD_STATE_DOWN) - reply->seqno = QETH_IDX_COMMAND_SEQNO; - else - reply->seqno = card->seqno.ipa++; + init_waitqueue_head(&reply->wait_q); - spin_lock_irqsave(&card->lock, flags); - list_add_tail(&reply->list, &card->cmd_waiter_list); - spin_unlock_irqrestore(&card->lock, flags); while (atomic_cmpxchg(&card->write.irq_pending, 0, 1)) ; - qeth_prepare_control_data(card, len, iob); if (IS_IPA(iob->data)) { cmd = __ipa_cmd(iob); + cmd->hdr.seqno = card->seqno.ipa++; + reply->seqno = cmd->hdr.seqno; event_timeout = QETH_IPA_TIMEOUT; } else { + reply->seqno = QETH_IDX_COMMAND_SEQNO; event_timeout = QETH_TIMEOUT; } + qeth_prepare_control_data(card, len, iob); + + spin_lock_irqsave(&card->lock, flags); + list_add_tail(&reply->list, &card->cmd_waiter_list); + spin_unlock_irqrestore(&card->lock, flags); timeout = jiffies + event_timeout; @@ -2933,7 +2934,7 @@ static void qeth_fill_ipacmd_header(struct qeth_card *card, memset(cmd, 0, sizeof(struct qeth_ipa_cmd)); cmd->hdr.command = command; cmd->hdr.initiator = IPA_CMD_INITIATOR_HOST; - cmd->hdr.seqno = card->seqno.ipa; + /* cmd->hdr.seqno is set by qeth_send_control_data() */ cmd->hdr.adapter_type = qeth_get_ipa_adp_type(card->info.link_type); cmd->hdr.rel_adapter_no = (__u8) card->info.portno; if (card->options.layer2) -- 2.13.5