Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756210AbbBCRB1 (ORCPT ); Tue, 3 Feb 2015 12:01:27 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35584 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756168AbbBCRA4 (ORCPT ); Tue, 3 Feb 2015 12:00:56 -0500 From: Vitaly Kuznetsov To: "K. Y. Srinivasan" , devel@linuxdriverproject.org Cc: Haiyang Zhang , linux-kernel@vger.kernel.org, Dexuan Cui , Jason Wang Subject: [PATCH 3/4] Drivers: hv: vmbus: protect vmbus_get_outgoing_channel() against channel removal Date: Tue, 3 Feb 2015 18:00:38 +0100 Message-Id: <1422982839-3948-4-git-send-email-vkuznets@redhat.com> In-Reply-To: <1422982839-3948-1-git-send-email-vkuznets@redhat.com> References: <1422982839-3948-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2474 Lines: 71 list_for_each_safe() we have in vmbus_get_outgoing_channel() works, however, we are not protected against the channel being removed (e.g. after receiving rescind offer). Users of this function (storvsc_do_io() is the only one at this moment) can get a link to an already freed channel. Make vmbus_get_outgoing_channel() search holding primary->lock as child channels are not being freed unless they're removed from parent's list. Signed-off-by: Vitaly Kuznetsov --- drivers/hv/channel_mgmt.c | 10 +++++++--- drivers/scsi/storvsc_drv.c | 2 ++ 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index fdccd16..af6243c 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -881,18 +881,20 @@ cleanup: */ struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary) { - struct list_head *cur, *tmp; + struct list_head *cur; int cur_cpu; struct vmbus_channel *cur_channel; struct vmbus_channel *outgoing_channel = primary; int cpu_distance, new_cpu_distance; + unsigned long flags; if (list_empty(&primary->sc_list)) - return outgoing_channel; + return vmbus_get_channel(outgoing_channel); cur_cpu = hv_context.vp_index[get_cpu()]; put_cpu(); - list_for_each_safe(cur, tmp, &primary->sc_list) { + spin_lock_irqsave(&primary->lock, flags); + list_for_each(cur, &primary->sc_list) { cur_channel = list_entry(cur, struct vmbus_channel, sc_list); if (cur_channel->state != CHANNEL_OPENED_STATE) continue; @@ -913,6 +915,8 @@ struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary) outgoing_channel = cur_channel; } + outgoing_channel = vmbus_get_channel(outgoing_channel); + spin_unlock_irqrestore(&primary->lock, flags); return outgoing_channel; } diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 4cff0dd..3b9b851 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -1370,6 +1370,8 @@ static int storvsc_do_io(struct hv_device *device, VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED); } + vmbus_put_channel(outgoing_channel); + if (ret != 0) return ret; -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/