From: "Richard W.M. Jones" <rjones@redhat.com>
To: jejb@linux.vnet.ibm.com
Cc: martin.petersen@oracle.com, mst@redhat.com, jasowang@redhat.com,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, hch@lst.de,
pbonzini@redhat.com
Subject: [PATCH v2 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN.
Date: Thu, 10 Aug 2017 17:56:51 +0100 [thread overview]
Message-ID: <20170810165652.21515-2-rjones@redhat.com> (raw)
In-Reply-To: <20170810165652.21515-1-rjones@redhat.com>
If using indirect descriptors, you can make the total_sg as large as
you want. If not, BUG is too serious because the function later
returns -ENOSPC.
Thanks Paolo Bonzini, Christoph Hellwig.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
drivers/virtio/virtio_ring.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5e1b548828e6..27cbc1eab868 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -296,7 +296,6 @@ static inline int virtqueue_add(struct virtqueue *_vq,
}
#endif
- BUG_ON(total_sg > vq->vring.num);
BUG_ON(total_sg == 0);
head = vq->free_head;
@@ -305,8 +304,10 @@ static inline int virtqueue_add(struct virtqueue *_vq,
* buffers, then go indirect. FIXME: tune this threshold */
if (vq->indirect && total_sg > 1 && vq->vq.num_free)
desc = alloc_indirect(_vq, total_sg, gfp);
- else
+ else {
desc = NULL;
+ WARN_ON_ONCE(total_sg > vq->vring.num && !vq->indirect);
+ }
if (desc) {
/* Use a single buffer which doesn't continue */
--
2.13.1
next prev parent reply other threads:[~2017-08-10 16:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-10 16:56 [PATCH v2 0/2] virtio_scsi: Set can_queue based on size of virtqueue Richard W.M. Jones
2017-08-10 16:56 ` Richard W.M. Jones [this message]
2017-08-10 16:56 ` [PATCH v2 2/2] virtio: virtio_scsi: Set can_queue to the length of the virtqueue Richard W.M. Jones
2017-08-10 16:58 ` Paolo Bonzini
2017-08-11 0:24 ` [PATCH v2 0/2] virtio_scsi: Set can_queue based on size of virtqueue Martin K. Petersen
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