From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julian Wiedmann Subject: [PATCH net 1/2] s390/qeth: fix underestimated count of buffer elements Date: Fri, 9 Feb 2018 11:03:49 +0100 Message-ID: <20180209100350.60572-2-jwi@linux.vnet.ibm.com> References: <20180209100350.60572-1-jwi@linux.vnet.ibm.com> Cc: , , Martin Schwidefsky , Heiko Carstens , Stefan Raspl , Ursula Braun , Julian Wiedmann To: David Miller Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35052 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751003AbeBIKEJ (ORCPT ); Fri, 9 Feb 2018 05:04:09 -0500 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w19A45Ow126511 for ; Fri, 9 Feb 2018 05:04:08 -0500 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0b-001b2d01.pphosted.com with ESMTP id 2g17mvvy4m-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 09 Feb 2018 05:04:08 -0500 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 9 Feb 2018 10:04:06 -0000 In-Reply-To: <20180209100350.60572-1-jwi@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Ursula Braun For a memory range/skb where the last byte falls onto a page boundary (ie. 'end' is of the form xxx...xxx001), the PFN_UP() part of the calculation currently doesn't round up to the next PFN due to an off-by-one error. Thus qeth believes that the skb occupies one page less than it actually does, and may select a IO buffer that doesn't have enough spare buffer elements to fit all of the skb's data. HW detects this as a malformed buffer descriptor, and raises an exception which then triggers device recovery. Fixes: 2863c61334aa ("qeth: refactor calculation of SBALE count") Signed-off-by: Ursula Braun Signed-off-by: Julian Wiedmann --- drivers/s390/net/qeth_core.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h index db42107bf2f5..c33fbc4c2e91 100644 --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -846,7 +846,7 @@ struct qeth_trap_id { */ static inline int qeth_get_elements_for_range(addr_t start, addr_t end) { - return PFN_UP(end - 1) - PFN_DOWN(start); + return PFN_UP(end) - PFN_DOWN(start); } static inline int qeth_get_micros(void) -- 2.13.5