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> Return-path: In-Reply-To: <20180209100350.60572-1-jwi@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-Archive: List-Post: To: David Miller Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky , Heiko Carstens , Stefan Raspl , Ursula Braun , Julian Wiedmann 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