From: Christian Schoenebeck <linux_oss@crudebyte.com>
To: v9fs-developer@lists.sourceforge.net
Cc: netdev@vger.kernel.org,
Dominique Martinet <asmadeus@codewreck.org>,
Eric Van Hensbergen <ericvh@gmail.com>,
Latchesar Ionkov <lucho@ionkov.net>, Greg Kurz <groug@kaod.org>,
Vivek Goyal <vgoyal@redhat.com>,
Nikolay Kichukov <nikolay@oldum.net>
Subject: [PATCH v4 07/12] 9p/trans_virtio: resize sg lists to whatever is possible
Date: Thu, 30 Dec 2021 14:23:18 +0100 [thread overview]
Message-ID: <35f29eb71a713fd6e595d8ea4d4f5131df5e33b8.1640870037.git.linux_oss@crudebyte.com> (raw)
In-Reply-To: <cover.1640870037.git.linux_oss@crudebyte.com>
Right now vq_sg_resize() used a lazy implementation following
the all-or-nothing princible. So it either resized exactly to
the requested new amount of sg lists, or it did not resize at
all.
The problem with this is if a user supplies a very large msize
value, resize would simply fail and the user would stick to
the default maximum msize supported by the virtio transport.
To resolve this potential issue, change vq_sg_resize() to resize
the passed sg list to whatever is possible on the machine.
Signed-off-by: Christian Schoenebeck <linux_oss@crudebyte.com>
---
net/9p/trans_virtio.c | 68 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 60 insertions(+), 8 deletions(-)
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index a02050c9742a..580efa95eabd 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -208,24 +208,67 @@ static struct virtqueue_sg *vq_sg_alloc(unsigned int nsgl)
* amount of lists
* @_vq_sg: scatter/gather lists to be resized
* @nsgl: new amount of scatter/gather lists
+ *
+ * Old scatter/gather lists are retained. Only growing the size is supported.
+ * If the requested amount cannot be satisfied, then lists are increased to
+ * whatever is possible.
*/
static int vq_sg_resize(struct virtqueue_sg **_vq_sg, unsigned int nsgl)
{
struct virtqueue_sg *vq_sg;
+ unsigned int i;
+ size_t sz;
+ int ret = 0;
BUG_ON(!_vq_sg || !nsgl);
vq_sg = *_vq_sg;
+ if (nsgl > VIRTQUEUE_SG_NSGL_MAX)
+ nsgl = VIRTQUEUE_SG_NSGL_MAX;
if (vq_sg->nsgl == nsgl)
return 0;
+ if (vq_sg->nsgl > nsgl)
+ return -ENOTSUPP;
+
+ vq_sg = kzalloc(sizeof(struct virtqueue_sg) +
+ nsgl * sizeof(struct scatterlist *),
+ GFP_KERNEL);
- /* lazy resize implementation for now */
- vq_sg = vq_sg_alloc(nsgl);
if (!vq_sg)
return -ENOMEM;
+ /* copy over old scatter gather lists */
+ sz = sizeof(struct virtqueue_sg) +
+ (*_vq_sg)->nsgl * sizeof(struct scatterlist *);
+ memcpy(vq_sg, *_vq_sg, sz);
+
+ vq_sg->nsgl = nsgl;
+
+ for (i = (*_vq_sg)->nsgl; i < nsgl; ++i) {
+ vq_sg->sgl[i] = kmalloc_array(
+ SG_MAX_SINGLE_ALLOC, sizeof(struct scatterlist),
+ GFP_KERNEL
+ );
+ /*
+ * handle failed allocation as soft error, we take whatever
+ * we get
+ */
+ if (!vq_sg->sgl[i]) {
+ ret = -ENOMEM;
+ vq_sg->nsgl = nsgl = i;
+ break;
+ }
+ sg_init_table(vq_sg->sgl[i], SG_MAX_SINGLE_ALLOC);
+ if (i) {
+ /* chain the lists */
+ sg_chain(vq_sg->sgl[i - 1], SG_MAX_SINGLE_ALLOC,
+ vq_sg->sgl[i]);
+ }
+ }
+ sg_mark_end(&vq_sg->sgl[nsgl - 1][SG_MAX_SINGLE_ALLOC - 1]);
+
kfree(*_vq_sg);
*_vq_sg = vq_sg;
- return 0;
+ return ret;
}
/**
@@ -846,12 +889,21 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args)
if (nsgl > chan->vq_sg->nsgl) {
/*
* if resize fails, no big deal, then just
- * continue with default msize instead
+ * continue with whatever we got
+ */
+ vq_sg_resize(&chan->vq_sg, nsgl);
+ /*
+ * actual allocation size might be less than
+ * requested, so use vq_sg->nsgl instead of nsgl
*/
- if (!vq_sg_resize(&chan->vq_sg, nsgl)) {
- client->trans_maxsize =
- PAGE_SIZE *
- ((nsgl * SG_USER_PAGES_PER_LIST) - 3);
+ client->trans_maxsize =
+ PAGE_SIZE * ((chan->vq_sg->nsgl *
+ SG_USER_PAGES_PER_LIST) - 3);
+ if (nsgl > chan->vq_sg->nsgl) {
+ pr_info("limiting 'msize' to %d as only %d "
+ "of %zu SG lists could be allocated",
+ client->trans_maxsize,
+ chan->vq_sg->nsgl, nsgl);
}
}
#endif /* CONFIG_ARCH_NO_SG_CHAIN */
--
2.30.2
next prev parent reply other threads:[~2021-12-30 14:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-30 13:23 [PATCH v4 00/12] remove msize limit in virtio transport Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 12/12] net/9p: allocate appropriate reduced message buffers Christian Schoenebeck
2022-04-02 14:05 ` Dominique Martinet
2022-04-03 11:29 ` Christian Schoenebeck
2022-04-03 12:37 ` Dominique Martinet
2022-04-03 14:00 ` Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 08/12] net/9p: limit 'msize' to KMALLOC_MAX_SIZE for all transports Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 04/12] 9p/trans_virtio: introduce struct virtqueue_sg Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 01/12] net/9p: show error message if user 'msize' cannot be satisfied Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 10/12] 9p: add P9_ERRMAX for 9p2000 and 9p2000.u Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 11/12] net/9p: add p9_msg_buf_size() Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 06/12] 9p/trans_virtio: support larger msize values Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 02/12] 9p/trans_virtio: separate allocation of scatter gather list Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 09/12] net/9p: split message size argument into 't_size' and 'r_size' pair Christian Schoenebeck
2021-12-30 13:23 ` Christian Schoenebeck [this message]
2021-12-30 13:23 ` [PATCH v4 05/12] net/9p: add trans_maxsize to struct p9_client Christian Schoenebeck
2021-12-30 13:23 ` [PATCH v4 03/12] 9p/trans_virtio: turn amount of sg lists into runtime info Christian Schoenebeck
2022-01-20 22:43 ` [PATCH v4 00/12] remove msize limit in virtio transport Nikolay Kichukov
2022-01-22 13:34 ` Christian Schoenebeck
2022-01-24 10:21 ` Nikolay Kichukov
2022-01-24 11:07 ` Dominique Martinet
2022-01-24 11:57 ` Christian Schoenebeck
2022-01-24 12:56 ` Dominique Martinet
2022-01-24 13:55 ` Christian Schoenebeck
2022-01-25 8:45 ` Nikolay Kichukov
2022-05-24 8:10 ` Nikolay Kichukov
2022-05-24 11:29 ` Christian Schoenebeck
2022-07-07 14:30 ` Christian Schoenebeck
[not found] ` <CAFkjPT=GAoViYd0E7CZQDq3ZjhmYT0DsBytfZXnE10JL0P8O-Q@mail.gmail.com>
2022-07-08 1:15 ` Dominique Martinet
[not found] ` <CAFkjPTngeFh=0mPVW-Yf1Sxkxp_HDNUeANndoYN3-eU9_rGLuQ@mail.gmail.com>
2022-07-08 11:18 ` Christian Schoenebeck
2022-07-08 11:40 ` Dominique Martinet
2022-07-08 13:00 ` Christian Schoenebeck
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