* Re: [dpdk-dev] [PATCH] vhost: fix external mbuf creation
2020-10-07 12:53 [dpdk-dev] [PATCH] vhost: fix external mbuf creation Olivier Matz
@ 2020-10-09 7:15 ` Maxime Coquelin
2020-10-09 7:24 ` Maxime Coquelin
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Maxime Coquelin @ 2020-10-09 7:15 UTC (permalink / raw)
To: Olivier Matz, dev
Cc: Chenbo Xia, Zhihong Wang, Flavio Leitner, yang_y_yi, stable
On 10/7/20 2:53 PM, Olivier Matz wrote:
> In virtio_dev_extbuf_alloc(), the shinfo structure used to store
> the reference counter and the free callback of the external buffer
> is by default stored inside the mbuf data.
>
> This is wrong because the mbuf (and its data) can be freed before
> the external buffer, for instance in the following situation:
>
> pkt2 = rte_pktmbuf_alloc(mp);
> rte_pktmbuf_attach(pkt2, pkt);
> rte_pktmbuf_free(pkt);
>
> After this, pkt is freed, but it still contains shinfo, which is
> referenced by pkt2.
>
> Fix this by always storing the shinfo beside the external buffer.
>
> Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer")
> Cc: stable@dpdk.org
>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>
> Hi,
>
> I found this issue by code review while discussing about this
> patchset [1]. I did not tested the patch, but as I'm only removing
> one path among the two, I don't expect that it breaks anything.
>
> [1] http://inbox.dpdk.org/dev/20200730120900.108232-1-yang_y_yi@163.com/
>
> Regards,
> Olivier
>
> lib/librte_vhost/virtio_net.c | 30 ++++++++----------------------
> 1 file changed, 8 insertions(+), 22 deletions(-)
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Thanks,
Maxime
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [dpdk-dev] [PATCH] vhost: fix external mbuf creation
2020-10-07 12:53 [dpdk-dev] [PATCH] vhost: fix external mbuf creation Olivier Matz
2020-10-09 7:15 ` Maxime Coquelin
@ 2020-10-09 7:24 ` Maxime Coquelin
2020-10-09 8:47 ` yang_y_yi
2020-10-09 9:04 ` yang_y_yi
3 siblings, 0 replies; 5+ messages in thread
From: Maxime Coquelin @ 2020-10-09 7:24 UTC (permalink / raw)
To: Olivier Matz, dev
Cc: Chenbo Xia, Zhihong Wang, Flavio Leitner, yang_y_yi, stable
On 10/7/20 2:53 PM, Olivier Matz wrote:
> In virtio_dev_extbuf_alloc(), the shinfo structure used to store
> the reference counter and the free callback of the external buffer
> is by default stored inside the mbuf data.
>
> This is wrong because the mbuf (and its data) can be freed before
> the external buffer, for instance in the following situation:
>
> pkt2 = rte_pktmbuf_alloc(mp);
> rte_pktmbuf_attach(pkt2, pkt);
> rte_pktmbuf_free(pkt);
>
> After this, pkt is freed, but it still contains shinfo, which is
> referenced by pkt2.
>
> Fix this by always storing the shinfo beside the external buffer.
>
> Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer")
> Cc: stable@dpdk.org
>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>
> Hi,
>
> I found this issue by code review while discussing about this
> patchset [1]. I did not tested the patch, but as I'm only removing
> one path among the two, I don't expect that it breaks anything.
>
> [1] http://inbox.dpdk.org/dev/20200730120900.108232-1-yang_y_yi@163.com/
>
> Regards,
> Olivier
>
> lib/librte_vhost/virtio_net.c | 30 ++++++++----------------------
> 1 file changed, 8 insertions(+), 22 deletions(-)
Applied to dpdk-next-virtio/main.
Thanks,
Maxime
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [dpdk-dev] [PATCH] vhost: fix external mbuf creation
2020-10-07 12:53 [dpdk-dev] [PATCH] vhost: fix external mbuf creation Olivier Matz
2020-10-09 7:15 ` Maxime Coquelin
2020-10-09 7:24 ` Maxime Coquelin
@ 2020-10-09 8:47 ` yang_y_yi
2020-10-09 9:04 ` yang_y_yi
3 siblings, 0 replies; 5+ messages in thread
From: yang_y_yi @ 2020-10-09 8:47 UTC (permalink / raw)
To: Olivier Matz
Cc: dev, Maxime Coquelin, Chenbo Xia, Zhihong Wang, Flavio Leitner, stable
Tested-by: Yi Yang <yangyi01@inspur.com>
At 2020-10-07 20:53:18, "Olivier Matz" <olivier.matz@6wind.com> wrote:
>In virtio_dev_extbuf_alloc(), the shinfo structure used to store
>the reference counter and the free callback of the external buffer
>is by default stored inside the mbuf data.
>
>This is wrong because the mbuf (and its data) can be freed before
>the external buffer, for instance in the following situation:
>
> pkt2 = rte_pktmbuf_alloc(mp);
> rte_pktmbuf_attach(pkt2, pkt);
> rte_pktmbuf_free(pkt);
>
>After this, pkt is freed, but it still contains shinfo, which is
>referenced by pkt2.
>
>Fix this by always storing the shinfo beside the external buffer.
>
>Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer")
>Cc: stable@dpdk.org
>
>Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
>---
>
>Hi,
>
>I found this issue by code review while discussing about this
>patchset [1]. I did not tested the patch, but as I'm only removing
>one path among the two, I don't expect that it breaks anything.
>
>[1] http://inbox.dpdk.org/dev/20200730120900.108232-1-yang_y_yi@163.com/
>
>Regards,
>Olivier
>
> lib/librte_vhost/virtio_net.c | 30 ++++++++----------------------
> 1 file changed, 8 insertions(+), 22 deletions(-)
>
>diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
>index 0a0bea1a5a..008f5ceb04 100644
>--- a/lib/librte_vhost/virtio_net.c
>+++ b/lib/librte_vhost/virtio_net.c
>@@ -2098,16 +2098,8 @@ virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size)
> rte_iova_t iova;
> void *buf;
>
>- /* Try to use pkt buffer to store shinfo to reduce the amount of memory
>- * required, otherwise store shinfo in the new buffer.
>- */
>- if (rte_pktmbuf_tailroom(pkt) >= sizeof(*shinfo))
>- shinfo = rte_pktmbuf_mtod(pkt,
>- struct rte_mbuf_ext_shared_info *);
>- else {
>- total_len += sizeof(*shinfo) + sizeof(uintptr_t);
>- total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));
>- }
>+ total_len += sizeof(*shinfo) + sizeof(uintptr_t);
>+ total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));
>
> if (unlikely(total_len > UINT16_MAX))
> return -ENOSPC;
>@@ -2118,18 +2110,12 @@ virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size)
> return -ENOMEM;
>
> /* Initialize shinfo */
>- if (shinfo) {
>- shinfo->free_cb = virtio_dev_extbuf_free;
>- shinfo->fcb_opaque = buf;
>- rte_mbuf_ext_refcnt_set(shinfo, 1);
>- } else {
>- shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
>- virtio_dev_extbuf_free, buf);
>- if (unlikely(shinfo == NULL)) {
>- rte_free(buf);
>- VHOST_LOG_DATA(ERR, "Failed to init shinfo\n");
>- return -1;
>- }
>+ shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
>+ virtio_dev_extbuf_free, buf);
>+ if (unlikely(shinfo == NULL)) {
>+ rte_free(buf);
>+ VHOST_LOG_DATA(ERR, "Failed to init shinfo\n");
>+ return -1;
> }
>
> iova = rte_malloc_virt2iova(buf);
>--
>2.25.1
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [dpdk-dev] [PATCH] vhost: fix external mbuf creation
2020-10-07 12:53 [dpdk-dev] [PATCH] vhost: fix external mbuf creation Olivier Matz
` (2 preceding siblings ...)
2020-10-09 8:47 ` yang_y_yi
@ 2020-10-09 9:04 ` yang_y_yi
3 siblings, 0 replies; 5+ messages in thread
From: yang_y_yi @ 2020-10-09 9:04 UTC (permalink / raw)
To: Olivier Matz
Cc: dev, Maxime Coquelin, Chenbo Xia, Zhihong Wang, Flavio Leitner, stable
Thanks Oliver for posting this patch, it clearly explain his concern, I totally agree this change. I tested it by OVS DPDK, it works well.
At 2020-10-07 20:53:18, "Olivier Matz" <olivier.matz@6wind.com> wrote:
>In virtio_dev_extbuf_alloc(), the shinfo structure used to store
>the reference counter and the free callback of the external buffer
>is by default stored inside the mbuf data.
>
>This is wrong because the mbuf (and its data) can be freed before
>the external buffer, for instance in the following situation:
>
> pkt2 = rte_pktmbuf_alloc(mp);
> rte_pktmbuf_attach(pkt2, pkt);
> rte_pktmbuf_free(pkt);
>
>After this, pkt is freed, but it still contains shinfo, which is
>referenced by pkt2.
>
>Fix this by always storing the shinfo beside the external buffer.
>
>Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer")
>Cc: stable@dpdk.org
>
>Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
>---
>
>Hi,
>
>I found this issue by code review while discussing about this
>patchset [1]. I did not tested the patch, but as I'm only removing
>one path among the two, I don't expect that it breaks anything.
>
>[1] http://inbox.dpdk.org/dev/20200730120900.108232-1-yang_y_yi@163.com/
>
>Regards,
>Olivier
>
> lib/librte_vhost/virtio_net.c | 30 ++++++++----------------------
> 1 file changed, 8 insertions(+), 22 deletions(-)
>
>diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
>index 0a0bea1a5a..008f5ceb04 100644
>--- a/lib/librte_vhost/virtio_net.c
>+++ b/lib/librte_vhost/virtio_net.c
>@@ -2098,16 +2098,8 @@ virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size)
> rte_iova_t iova;
> void *buf;
>
>- /* Try to use pkt buffer to store shinfo to reduce the amount of memory
>- * required, otherwise store shinfo in the new buffer.
>- */
>- if (rte_pktmbuf_tailroom(pkt) >= sizeof(*shinfo))
>- shinfo = rte_pktmbuf_mtod(pkt,
>- struct rte_mbuf_ext_shared_info *);
>- else {
>- total_len += sizeof(*shinfo) + sizeof(uintptr_t);
>- total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));
>- }
>+ total_len += sizeof(*shinfo) + sizeof(uintptr_t);
>+ total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));
>
> if (unlikely(total_len > UINT16_MAX))
> return -ENOSPC;
>@@ -2118,18 +2110,12 @@ virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size)
> return -ENOMEM;
>
> /* Initialize shinfo */
>- if (shinfo) {
>- shinfo->free_cb = virtio_dev_extbuf_free;
>- shinfo->fcb_opaque = buf;
>- rte_mbuf_ext_refcnt_set(shinfo, 1);
>- } else {
>- shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
>- virtio_dev_extbuf_free, buf);
>- if (unlikely(shinfo == NULL)) {
>- rte_free(buf);
>- VHOST_LOG_DATA(ERR, "Failed to init shinfo\n");
>- return -1;
>- }
>+ shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
>+ virtio_dev_extbuf_free, buf);
>+ if (unlikely(shinfo == NULL)) {
>+ rte_free(buf);
>+ VHOST_LOG_DATA(ERR, "Failed to init shinfo\n");
>+ return -1;
> }
>
> iova = rte_malloc_virt2iova(buf);
>--
>2.25.1
^ permalink raw reply [flat|nested] 5+ messages in thread