From: "Hu, Jiayu" <jiayu.hu@intel.com>
To: "yang_y_yi@163.com" <yang_y_yi@163.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"techboard@dpdk.org" <techboard@dpdk.org>,
"thomas@monjalon.net" <thomas@monjalon.net>,
"yangyi01@inspur.com" <yangyi01@inspur.com>
Subject: Re: [dpdk-dev] [PATCH v3] gso: fix free issue of mbuf gso segments attach to
Date: Wed, 28 Oct 2020 00:51:06 +0000 [thread overview]
Message-ID: <6e66c84f673c41688b58286693d78334@intel.com> (raw)
In-Reply-To: <20201026064713.33316-1-yang_y_yi@163.com>
Acked-by: Jiayu Hu <jiayu.hu@intel.com>
> -----Original Message-----
> From: yang_y_yi@163.com <yang_y_yi@163.com>
> Sent: Monday, October 26, 2020 2:47 PM
> To: dev@dpdk.org
> Cc: Hu, Jiayu <jiayu.hu@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; techboard@dpdk.org;
> thomas@monjalon.net; yangyi01@inspur.com; yang_y_yi@163.com
> Subject: [PATCH v3] gso: fix free issue of mbuf gso segments attach to
>
> From: Yi Yang <yangyi01@inspur.com>
>
> rte_gso_segment decreased refcnt of pkt by one, but
> it is wrong if pkt is external mbuf, pkt won't be
> freed because of incorrect refcnt, the result is
> application can't allocate mbuf from mempool because
> mbufs in mempool are run out of.
>
> One correct way is application should call
> rte_pktmbuf_free after calling rte_gso_segment to free
> pkt explicitly. rte_gso_segment mustn't handle it, this
> should be responsibility of application.
>
> This commit changed rte_gso_segment in functional behavior
> and return value, so the application must take appropriate
> actions according to return values, "ret < 0" means it
> should free and drop 'pkt', "ret == 0" means 'pkt' isn't
> GSOed but 'pkt' can be transimmitted as a normal packet,
> "ret > 0" means 'pkt' has been GSOed into two or multiple
> segments, it should use "pkts_out" to transmit these
> segments. The application must free 'pkt' after call
> rte_gso_segment when return value isn't equal to 0.
>
> Fixes: 119583797b6a ("gso: support TCP/IPv4 GSO")
> Signed-off-by: Yi Yang <yangyi01@inspur.com>
> ---
> Changelog:
>
> v2->v3:
> - add release notes to emphasize behavior and return
> value changes of rte_gso_segment().
> - update return value description of rte_gso_segment().
> - modify related code to adapt to the changes.
>
> v1->v2:
> - update description of rte_gso_segment().
> - change code which calls rte_gso_segment() to
> fix free issue.
>
> ---
> app/test-pmd/csumonly.c | 12 ++++++++++--
> .../prog_guide/generic_segmentation_offload_lib.rst | 7 +++++--
> doc/guides/rel_notes/release_20_11.rst | 7 +++++++
> drivers/net/tap/rte_eth_tap.c | 12 ++++++++++--
> lib/librte_gso/gso_tcp4.c | 6 ++----
> lib/librte_gso/gso_tunnel_tcp4.c | 14 +++++---------
> lib/librte_gso/gso_udp4.c | 6 ++----
> lib/librte_gso/rte_gso.c | 15 +++------------
> lib/librte_gso/rte_gso.h | 8 ++++++--
> 9 files changed, 50 insertions(+), 37 deletions(-)
>
> diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
> index 3d7d244..d813d4f 100644
> --- a/app/test-pmd/csumonly.c
> +++ b/app/test-pmd/csumonly.c
> @@ -1080,9 +1080,17 @@ struct simple_gre_hdr {
> ret = rte_gso_segment(pkts_burst[i], gso_ctx,
> &gso_segments[nb_segments],
> GSO_MAX_PKT_BURST -
> nb_segments);
> - if (ret >= 0)
> + if (ret >= 1) {
> + /* pkts_burst[i] can be freed safely here. */
> + rte_pktmbuf_free(pkts_burst[i]);
> nb_segments += ret;
> - else {
> + } else if (ret == 0) {
> + /* 0 means it can be transmitted directly
> + * without gso.
> + */
> + gso_segments[nb_segments] = pkts_burst[i];
> + nb_segments += 1;
> + } else {
> TESTPMD_LOG(DEBUG, "Unable to segment
> packet");
> rte_pktmbuf_free(pkts_burst[i]);
> }
> diff --git a/doc/guides/prog_guide/generic_segmentation_offload_lib.rst
> b/doc/guides/prog_guide/generic_segmentation_offload_lib.rst
> index 205cb8a..8577572 100644
> --- a/doc/guides/prog_guide/generic_segmentation_offload_lib.rst
> +++ b/doc/guides/prog_guide/generic_segmentation_offload_lib.rst
> @@ -25,8 +25,9 @@ Bearing that in mind, the GSO library enables DPDK
> applications to segment
> packets in software. Note however, that GSO is implemented as a
> standalone
> library, and not via a 'fallback' mechanism (i.e. for when TSO is unsupported
> in the underlying hardware); that is, applications must explicitly invoke the
> -GSO library to segment packets. The size of GSO segments ``(segsz)`` is
> -configurable by the application.
> +GSO library to segment packets, they also must call ``rte_pktmbuf_free()`` to
> +free mbuf GSO segments attach to after calling ``rte_gso_segment()``. The
> size
> +of GSO segments ``(segsz)`` is configurable by the application.
>
> Limitations
> -----------
> @@ -233,6 +234,8 @@ To segment an outgoing packet, an application must:
>
> #. Invoke the GSO segmentation API, ``rte_gso_segment()``.
>
> +#. Call ``rte_pktmbuf_free()`` to free mbuf ``rte_gso_segment()`` segments.
> +
> #. If required, update the L3 and L4 checksums of the newly-created
> segments.
> For tunneled packets, the outer IPv4 headers' checksums should also be
> updated. Alternatively, the application may offload checksum calculation
> diff --git a/doc/guides/rel_notes/release_20_11.rst
> b/doc/guides/rel_notes/release_20_11.rst
> index d8ac359..da77396 100644
> --- a/doc/guides/rel_notes/release_20_11.rst
> +++ b/doc/guides/rel_notes/release_20_11.rst
> @@ -543,6 +543,13 @@ API Changes
> * sched: Removed ``tb_rate``, ``tc_rate``, ``tc_period`` and ``tb_size``
> from ``struct rte_sched_subport_params``.
>
> +* **Changed ``rte_gso_segment`` in functional behavior and return value.**
> +
> + * Don't save pkt to pkts_out[0] if it isn't GSOed in case of ret == 1.
> + * Return 0 instead of 1 for the above case.
> + * ``rte_gso_segment`` won't free pkt no matter whether it is GSOed, the
> + application has responsibility to free it after call ``rte_gso_segment``.
> +
>
> ABI Changes
> -----------
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index 81c6884..2f8abb1 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -751,8 +751,16 @@ struct ipc_queues {
> if (num_tso_mbufs < 0)
> break;
>
> - mbuf = gso_mbufs;
> - num_mbufs = num_tso_mbufs;
> + if (num_tso_mbufs >= 1) {
> + mbuf = gso_mbufs;
> + num_mbufs = num_tso_mbufs;
> + } else {
> + /* 0 means it can be transmitted directly
> + * without gso.
> + */
> + mbuf = &mbuf_in;
> + num_mbufs = 1;
> + }
> } else {
> /* stats.errs will be incremented */
> if (rte_pktmbuf_pkt_len(mbuf_in) > max_size)
> diff --git a/lib/librte_gso/gso_tcp4.c b/lib/librte_gso/gso_tcp4.c
> index ade172a..d31feaf 100644
> --- a/lib/librte_gso/gso_tcp4.c
> +++ b/lib/librte_gso/gso_tcp4.c
> @@ -50,15 +50,13 @@
> pkt->l2_len);
> frag_off = rte_be_to_cpu_16(ipv4_hdr->fragment_offset);
> if (unlikely(IS_FRAGMENTED(frag_off))) {
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
>
> /* Don't process the packet without data */
> hdr_offset = pkt->l2_len + pkt->l3_len + pkt->l4_len;
> if (unlikely(hdr_offset >= pkt->pkt_len)) {
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
>
> pyld_unit_size = gso_size - hdr_offset;
> diff --git a/lib/librte_gso/gso_tunnel_tcp4.c
> b/lib/librte_gso/gso_tunnel_tcp4.c
> index e0384c2..166aace 100644
> --- a/lib/librte_gso/gso_tunnel_tcp4.c
> +++ b/lib/librte_gso/gso_tunnel_tcp4.c
> @@ -62,7 +62,7 @@
> {
> struct rte_ipv4_hdr *inner_ipv4_hdr;
> uint16_t pyld_unit_size, hdr_offset, frag_off;
> - int ret = 1;
> + int ret;
>
> hdr_offset = pkt->outer_l2_len + pkt->outer_l3_len + pkt->l2_len;
> inner_ipv4_hdr = (struct rte_ipv4_hdr *)(rte_pktmbuf_mtod(pkt,
> char *) +
> @@ -73,25 +73,21 @@
> */
> frag_off = rte_be_to_cpu_16(inner_ipv4_hdr->fragment_offset);
> if (unlikely(IS_FRAGMENTED(frag_off))) {
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
>
> hdr_offset += pkt->l3_len + pkt->l4_len;
> /* Don't process the packet without data */
> if (hdr_offset >= pkt->pkt_len) {
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
> pyld_unit_size = gso_size - hdr_offset;
>
> /* Segment the payload */
> ret = gso_do_segment(pkt, hdr_offset, pyld_unit_size, direct_pool,
> indirect_pool, pkts_out, nb_pkts_out);
> - if (ret <= 1)
> - return ret;
> -
> - update_tunnel_ipv4_tcp_headers(pkt, ipid_delta, pkts_out, ret);
> + if (ret > 1)
> + update_tunnel_ipv4_tcp_headers(pkt, ipid_delta, pkts_out,
> ret);
>
> return ret;
> }
> diff --git a/lib/librte_gso/gso_udp4.c b/lib/librte_gso/gso_udp4.c
> index 6fa68f2..5d0186a 100644
> --- a/lib/librte_gso/gso_udp4.c
> +++ b/lib/librte_gso/gso_udp4.c
> @@ -52,8 +52,7 @@
> pkt->l2_len);
> frag_off = rte_be_to_cpu_16(ipv4_hdr->fragment_offset);
> if (unlikely(IS_FRAGMENTED(frag_off))) {
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
>
> /*
> @@ -65,8 +64,7 @@
>
> /* Don't process the packet without data. */
> if (unlikely(hdr_offset + pkt->l4_len >= pkt->pkt_len)) {
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
>
> /* pyld_unit_size must be a multiple of 8 because frag_off
> diff --git a/lib/librte_gso/rte_gso.c b/lib/librte_gso/rte_gso.c
> index 751b5b6..896350e 100644
> --- a/lib/librte_gso/rte_gso.c
> +++ b/lib/librte_gso/rte_gso.c
> @@ -30,7 +30,6 @@
> uint16_t nb_pkts_out)
> {
> struct rte_mempool *direct_pool, *indirect_pool;
> - struct rte_mbuf *pkt_seg;
> uint64_t ol_flags;
> uint16_t gso_size;
> uint8_t ipid_delta;
> @@ -44,8 +43,7 @@
>
> if (gso_ctx->gso_size >= pkt->pkt_len) {
> pkt->ol_flags &= (~(PKT_TX_TCP_SEG | PKT_TX_UDP_SEG));
> - pkts_out[0] = pkt;
> - return 1;
> + return 0;
> }
>
> direct_pool = gso_ctx->direct_pool;
> @@ -75,18 +73,11 @@
> indirect_pool, pkts_out, nb_pkts_out);
> } else {
> /* unsupported packet, skip */
> - pkts_out[0] = pkt;
> RTE_LOG(DEBUG, GSO, "Unsupported packet type\n");
> - return 1;
> + ret = 0;
> }
>
> - if (ret > 1) {
> - pkt_seg = pkt;
> - while (pkt_seg) {
> - rte_mbuf_refcnt_update(pkt_seg, -1);
> - pkt_seg = pkt_seg->next;
> - }
> - } else if (ret < 0) {
> + if (ret < 0) {
> /* Revert the ol_flags in the event of failure. */
> pkt->ol_flags = ol_flags;
> }
> diff --git a/lib/librte_gso/rte_gso.h b/lib/librte_gso/rte_gso.h
> index 3aab297..af480ee 100644
> --- a/lib/librte_gso/rte_gso.h
> +++ b/lib/librte_gso/rte_gso.h
> @@ -89,8 +89,11 @@ struct rte_gso_ctx {
> * the GSO segments are sent to should support transmission of multi-
> segment
> * packets.
> *
> - * If the input packet is GSO'd, its mbuf refcnt reduces by 1. Therefore,
> - * when all GSO segments are freed, the input packet is freed automatically.
> + * If the input packet is GSO'd, all the indirect segments are attached to the
> + * input packet.
> + *
> + * rte_gso_segment() will not free the input packet no matter whether it is
> + * GSO'd or not, the application should free it after call rte_gso_segment().
> *
> * If the memory space in pkts_out or MBUF pools is insufficient, this
> * function fails, and it returns (-1) * errno. Otherwise, GSO succeeds,
> @@ -109,6 +112,7 @@ struct rte_gso_ctx {
> *
> * @return
> * - The number of GSO segments filled in pkts_out on success.
> + * - Return 0 if it needn't GSOed.
> * - Return -ENOMEM if run out of memory in MBUF pools.
> * - Return -EINVAL for invalid parameters.
> */
> --
> 1.8.3.1
prev parent reply other threads:[~2020-10-28 0:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 6:47 yang_y_yi
2020-10-27 19:55 ` Ananyev, Konstantin
2020-10-29 21:39 ` Thomas Monjalon
2020-11-03 21:34 ` Thomas Monjalon
2020-11-04 0:35 ` yang_y_yi
2020-10-28 0:51 ` Hu, Jiayu [this message]
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