From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Venkateswararao Jujjuri (JV)" Subject: [PATCH 1/2] [net/9p] Set the condition just before waking up. Date: Mon, 14 Mar 2011 15:12:41 -0700 Message-ID: <1300140761-8769-1-git-send-email-jvrao@linux.vnet.ibm.com> Cc: linux-fsdevel@vger.kernel.org, "Venkateswararao Jujjuri (JV)" To: v9fs-developer@lists.sourceforge.net Return-path: Received: from e34.co.us.ibm.com ([32.97.110.152]:38724 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751659Ab1CNVf1 (ORCPT ); Mon, 14 Mar 2011 17:35:27 -0400 Received: from d03relay01.boulder.ibm.com (d03relay01.boulder.ibm.com [9.17.195.226]) by e34.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p2ELNeIm011924 for ; Mon, 14 Mar 2011 15:23:40 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay01.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p2ELZOZM098458 for ; Mon, 14 Mar 2011 15:35:24 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p2ELZNWk014949 for ; Mon, 14 Mar 2011 15:35:24 -0600 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Given that the sprious wake-ups are common, we need to move the condition setting right next to the wake_up(). After setting the condition to req->status = REQ_STATUS_RCVD, sprious wakeups may cause the virtqueue back on the free list for someone else to use. This may result in kernel panic while relasing the pinned pages in p9_release_req_pages(). Also rearranged the while loop in req_done() for better redability. Signed-off-by: Venkateswararao Jujjuri --- net/9p/trans_virtio.c | 44 ++++++++++++++++++++++---------------------- 1 files changed, 22 insertions(+), 22 deletions(-) diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 961e025..cb98af9 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -141,33 +141,33 @@ static void req_done(struct virtqueue *vq) P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n"); - do { + while (1) { spin_lock_irqsave(&chan->lock, flags); rc = virtqueue_get_buf(chan->vq, &len); - if (rc != NULL) { - chan->ring_bufs_avail = 1; - spin_unlock_irqrestore(&chan->lock, flags); - /* Wakeup if anyone waiting for VirtIO ring space. */ - wake_up(chan->vc_wq); - P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc); - P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", - rc->tag); - req = p9_tag_lookup(chan->client, rc->tag); - req->status = REQ_STATUS_RCVD; - if (req->tc->private) { - struct trans_rpage_info *rp = req->tc->private; - /*Release pages */ - p9_release_req_pages(rp); - if (rp->rp_alloc) - kfree(rp); - req->tc->private = NULL; - } - p9_client_cb(chan->client, req); - } else { + if (rc == NULL) { spin_unlock_irqrestore(&chan->lock, flags); + break; } - } while (rc != NULL); + + chan->ring_bufs_avail = 1; + spin_unlock_irqrestore(&chan->lock, flags); + /* Wakeup if anyone waiting for VirtIO ring space. */ + wake_up(chan->vc_wq); + P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc); + P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); + req = p9_tag_lookup(chan->client, rc->tag); + if (req->tc->private) { + struct trans_rpage_info *rp = req->tc->private; + /*Release pages */ + p9_release_req_pages(rp); + if (rp->rp_alloc) + kfree(rp); + req->tc->private = NULL; + } + req->status = REQ_STATUS_RCVD; + p9_client_cb(chan->client, req); + } } /** -- 1.6.5.2