From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934090AbcJaFtu (ORCPT ); Mon, 31 Oct 2016 01:49:50 -0400 Received: from p3plsmtps2ded01.prod.phx3.secureserver.net ([208.109.80.58]:41704 "EHLO p3plsmtps2ded01.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759051AbcJaFs7 (ORCPT ); Mon, 31 Oct 2016 01:48:59 -0400 x-originating-ip: 72.167.245.219 From: kys@exchange.microsoft.com To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, vkuznets@redhat.com, jasowang@redhat.com, leann.ogasawara@canonical.com, sthemmin@microsoft.com Cc: "K. Y. Srinivasan" Subject: [PATCH 01/15] Drivers: hv: ring_buffer: count on wrap around mappings in get_next_pkt_raw() (v2) Date: Mon, 31 Oct 2016 00:41:36 -0700 Message-Id: <1477899710-28675-1-git-send-email-kys@exchange.microsoft.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1477899668-28635-1-git-send-email-kys@exchange.microsoft.com> References: <1477899668-28635-1-git-send-email-kys@exchange.microsoft.com> Reply-To: kys@microsoft.com X-CMAE-Envelope: MS4wfOoBE6Kf+u6UIOV3WwBQbJ1C3EsneSBC8gk3KzGgX+/PqWun4GoApn18mOd5vzem9bdUoMGbvp1DpHsiwosUTGjj6DFBy8UMZKLF9pjR3e5RtVut7qpY tvKJGldl1yVmMnPlGRIXpdREH2jPp/KbeGnUkUOk7QFpbK/trzsm/1qAl3U+EfK6/DWh/2Tg6sdfO/af11QSdsqOCaB5fVNpf6aaGr6maONiPIvaoTrpk5ct mmVn4Ujm5wbPyjBXSEzhC0UX+buA+qie0bcK0K6oPvuEakoPW5DMVX/bbVe8+gsdVhYlWztuTatWWDW08T6EZHHO2UuqOGN0XRIhdhfyD3YrnTMq813fAnnR FitJICXXqJ8M0+0h37SKkdwQ2OMXKkZ2Wyod11qRVS3a55yjW9mS8Sd6EN6P2Jy9kEBYrAnRtyPP6FA3S/zEteDvRL/v+OS98CjjQkbWYDslwc+Dehx2Pofc LtZXQj03c1owPP4nn0bmRjzDAB1WQfZCthxkNA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vitaly Kuznetsov With wrap around mappings in place we can always provide drivers with direct links to packets on the ring buffer, even when they wrap around. Do the required updates to get_next_pkt_raw()/put_pkt_raw() The first version of this commit was reverted (65a532f3d50a) to deal with cross-tree merge issues which are (hopefully) resolved now. Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Tested-by: Dexuan Cui --- include/linux/hyperv.h | 32 +++++++++++--------------------- 1 files changed, 11 insertions(+), 21 deletions(-) diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index cd184bd..2f65c30 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -1519,31 +1519,23 @@ static inline struct vmpacket_descriptor * get_next_pkt_raw(struct vmbus_channel *channel) { struct hv_ring_buffer_info *ring_info = &channel->inbound; - u32 read_loc = ring_info->priv_read_index; + u32 priv_read_loc = ring_info->priv_read_index; void *ring_buffer = hv_get_ring_buffer(ring_info); - struct vmpacket_descriptor *cur_desc; - u32 packetlen; u32 dsize = ring_info->ring_datasize; - u32 delta = read_loc - ring_info->ring_buffer->read_index; + /* + * delta is the difference between what is available to read and + * what was already consumed in place. We commit read index after + * the whole batch is processed. + */ + u32 delta = priv_read_loc >= ring_info->ring_buffer->read_index ? + priv_read_loc - ring_info->ring_buffer->read_index : + (dsize - ring_info->ring_buffer->read_index) + priv_read_loc; u32 bytes_avail_toread = (hv_get_bytes_to_read(ring_info) - delta); if (bytes_avail_toread < sizeof(struct vmpacket_descriptor)) return NULL; - if ((read_loc + sizeof(*cur_desc)) > dsize) - return NULL; - - cur_desc = ring_buffer + read_loc; - packetlen = cur_desc->len8 << 3; - - /* - * If the packet under consideration is wrapping around, - * return failure. - */ - if ((read_loc + packetlen + VMBUS_PKT_TRAILER) > (dsize - 1)) - return NULL; - - return cur_desc; + return ring_buffer + priv_read_loc; } /* @@ -1555,16 +1547,14 @@ static inline void put_pkt_raw(struct vmbus_channel *channel, struct vmpacket_descriptor *desc) { struct hv_ring_buffer_info *ring_info = &channel->inbound; - u32 read_loc = ring_info->priv_read_index; u32 packetlen = desc->len8 << 3; u32 dsize = ring_info->ring_datasize; - if ((read_loc + packetlen + VMBUS_PKT_TRAILER) > dsize) - BUG(); /* * Include the packet trailer. */ ring_info->priv_read_index += packetlen + VMBUS_PKT_TRAILER; + ring_info->priv_read_index %= dsize; } /* -- 1.7.4.1