From: Stephen Hemminger <stephen@networkplumber.org>
To: "Mário Kuka" <kuka@cesnet.cz>
Cc: Reshma Pattan <reshma.pattan@intel.com>,
Ray Kinsella <mdr@ashroe.eu>,
dev@dpdk.org
Subject: Re: [PATCH] pcapng: fix write more packets than IOV_MAX limit
Date: Mon, 25 Jul 2022 09:10:49 -0700 [thread overview]
Message-ID: <20220725091049.5d9d013c@hermes.local> (raw)
In-Reply-To: <20220725152811.409447-1-kuka@cesnet.cz>
On Mon, 25 Jul 2022 17:28:11 +0200
Mário Kuka <kuka@cesnet.cz> wrote:
> The rte_pcapng_write_packets() function fails when we try to write more
> packets than the IOV_MAX limit. The error is caused by the writev()
> system call, which is limited by the IOV_MAX limit. The iovcnt argument
> is valid if it is greater than 0 and less than or equal to IOV_MAX as
> defined in <limits.h>.
>
> To avoid this problem, we can split the iovec buffer into smaller
> chunks with a maximum size of IOV_MAX and write them sequentially by
> calling the writev() repeatedly.
>
> Fixes: 8d23ce8f5ee9 ("pcapng: add new library for writing pcapng files")
> Cc: stephen@networkplumber.org
>
> Signed-off-by: Mário Kuka <kuka@cesnet.cz>
> ---
Something like this (compile tested only).
diff --git a/lib/pcapng/rte_pcapng.c b/lib/pcapng/rte_pcapng.c
index 06ad712bd1eb..e41cf909e120 100644
--- a/lib/pcapng/rte_pcapng.c
+++ b/lib/pcapng/rte_pcapng.c
@@ -551,33 +551,16 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
return NULL;
}
-/* Count how many segments are in this array of mbufs */
-static unsigned int
-mbuf_burst_segs(struct rte_mbuf *pkts[], unsigned int n)
-{
- unsigned int i, iovcnt;
-
- for (iovcnt = 0, i = 0; i < n; i++) {
- const struct rte_mbuf *m = pkts[i];
-
- __rte_mbuf_sanity_check(m, 1);
-
- iovcnt += m->nb_segs;
- }
- return iovcnt;
-}
-
/* Write pre-formatted packets to file. */
ssize_t
rte_pcapng_write_packets(rte_pcapng_t *self,
struct rte_mbuf *pkts[], uint16_t nb_pkts)
{
- int iovcnt = mbuf_burst_segs(pkts, nb_pkts);
- struct iovec iov[iovcnt];
- unsigned int i, cnt;
- ssize_t ret;
+ struct iovec iov[IOV_MAX];
+ unsigned int i, cnt = 0;
+ ssize_t ret, total = 0;
- for (i = cnt = 0; i < nb_pkts; i++) {
+ for (i = 0; i < nb_pkts; i++) {
struct rte_mbuf *m = pkts[i];
struct pcapng_enhance_packet_block *epb;
@@ -589,6 +572,20 @@ rte_pcapng_write_packets(rte_pcapng_t *self,
return -1;
}
+ /*
+ * Handle case of highly fragmented and large burst size
+ * Note: this assumes that max segments per mbuf < IOV_MAX
+ */
+ if (unlikely(cnt + m->nb_segs >= IOV_MAX)) {
+ ret = writev(self->outfd, iov, cnt);
+ if (unlikely(ret < 0)) {
+ rte_errno = errno;
+ return -1;
+ }
+ total += ret;
+ cnt = 0;
+ }
+
/*
* The DPDK port is recorded during pcapng_copy.
* Map that to PCAPNG interface in file.
@@ -601,10 +598,12 @@ rte_pcapng_write_packets(rte_pcapng_t *self,
} while ((m = m->next));
}
- ret = writev(self->outfd, iov, iovcnt);
- if (unlikely(ret < 0))
+ ret = writev(self->outfd, iov, cnt);
+ if (unlikely(ret < 0)) {
rte_errno = errno;
- return ret;
+ return -1;
+ }
+ return total + ret;
}
/* Create new pcapng writer handle */
next prev parent reply other threads:[~2022-07-25 16:10 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-25 15:28 Mário Kuka
2022-07-25 15:57 ` Stephen Hemminger
2022-07-25 16:10 ` Stephen Hemminger [this message]
2022-07-29 7:18 ` [PATCH v2 0/2] pcapng: fix some issues with writing packets Mário Kuka
2022-07-29 7:18 ` [PATCH v2 1/2] pcapng: fix write more packets than IOV_MAX limit Mário Kuka
2022-07-29 7:18 ` [PATCH v2 2/2] pcapng: check if writev() returns a partial write Mário Kuka
2022-07-29 16:00 ` Stephen Hemminger
2022-07-29 17:08 ` Mário Kuka
2022-07-29 18:14 ` Stephen Hemminger
2022-08-01 8:42 ` Mário Kuka
2022-07-29 15:58 ` [PATCH v2 0/2] pcapng: fix some issues with writing packets Stephen Hemminger
2022-07-29 17:33 ` Mário Kuka
2022-08-01 8:40 ` [PATCH v3] pcapng: fix write more packets than IOV_MAX limit Mário Kuka
2022-08-01 15:33 ` Stephen Hemminger
2022-10-10 0:40 ` Thomas Monjalon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220725091049.5d9d013c@hermes.local \
--to=stephen@networkplumber.org \
--cc=dev@dpdk.org \
--cc=kuka@cesnet.cz \
--cc=mdr@ashroe.eu \
--cc=reshma.pattan@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).