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Message-ID: <20210809140505.30388445@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date: Mon, 9 Aug 2021 14:05:05 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Nicholas Richardson <richardsonnick@...gle.com>
Cc: davem@...emloft.net, nrrichar@...u.edu, arunkaly@...gle.com,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
Yejune Deng <yejune.deng@...il.com>,
Di Zhu <zhudi21@...wei.com>, Ye Bin <yebin10@...wei.com>,
Leesoo Ahn <dev@...eel.net>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] pktgen: Parse internet mix (imix) input
On Mon, 9 Aug 2021 17:22:02 +0000 Nicholas Richardson wrote:
> From: Nick Richardson <richardsonnick@...gle.com>
>
> Adds "imix_weights" command for specifying internet mix distribution.
>
> The command is in this format:
> "imix_weights size_1,weight_1 size_2,weight_2 ... size_n,weight_n"
> where the probability that packet size_i is picked is:
> weight_i / (weight_1 + weight_2 + .. + weight_n)
>
> The user may provide up to 20 imix entries (size_i,weight_i) in this
> command.
>
> The user specified imix entries will be displayed in the "Params"
> section of the interface output.
>
> Values for clone_skb > 0 is not supported in IMIX mode.
>
> Summary of changes:
> Add flag for enabling internet mix mode.
> Add command (imix_weights) for internet mix input.
> Return -ENOTSUPP when clone_skb > 0 in IMIX mode.
> Display imix_weights in Params.
> Create data structures to store imix entries and distribution.
>
> Signed-off-by: Nick Richardson <richardsonnick@...gle.com>
> ---
> net/core/pktgen.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 95 insertions(+)
>
> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> index 7e258d255e90..83c83e1b5f28 100644
> --- a/net/core/pktgen.c
> +++ b/net/core/pktgen.c
> @@ -175,6 +175,8 @@
> #define IP_NAME_SZ 32
> #define MAX_MPLS_LABELS 16 /* This is the max label stack depth */
> #define MPLS_STACK_BOTTOM htonl(0x00000100)
> +/* Max number of internet mix entries that can be specified in imix_weights. */
> +#define MAX_IMIX_ENTRIES 20
>
> #define func_enter() pr_debug("entering %s\n", __func__);
>
> @@ -242,6 +244,12 @@ static char *pkt_flag_names[] = {
> #define VLAN_TAG_SIZE(x) ((x)->vlan_id == 0xffff ? 0 : 4)
> #define SVLAN_TAG_SIZE(x) ((x)->svlan_id == 0xffff ? 0 : 4)
>
> +struct imix_pkt {
> + __u64 size;
> + __u64 weight;
> + __u64 count_so_far;
no need for the __ prefix outside of uAPI.
> +};
> +
> struct flow_state {
> __be32 cur_daddr;
> int count;
> @@ -343,6 +351,10 @@ struct pktgen_dev {
> __u8 traffic_class; /* ditto for the (former) Traffic Class in IPv6
> (see RFC 3260, sec. 4) */
>
> + /* IMIX */
> + unsigned int n_imix_entries;
> + struct imix_pkt imix_entries[MAX_IMIX_ENTRIES];
> +
> /* MPLS */
> unsigned int nr_labels; /* Depth of stack, 0 = no MPLS */
> __be32 labels[MAX_MPLS_LABELS];
> @@ -552,6 +564,16 @@ static int pktgen_if_show(struct seq_file *seq, void *v)
> (unsigned long long)pkt_dev->count, pkt_dev->min_pkt_size,
> pkt_dev->max_pkt_size);
>
> + if (pkt_dev->n_imix_entries > 0) {
> + seq_printf(seq, " imix_weights: ");
> + for (i = 0; i < pkt_dev->n_imix_entries; i++) {
> + seq_printf(seq, "%llu,%llu ",
> + pkt_dev->imix_entries[i].size,
> + pkt_dev->imix_entries[i].weight);
> + }
> + seq_printf(seq, "\n");
seq_puts()
> + }
> +
> seq_printf(seq,
> " frags: %d delay: %llu clone_skb: %d ifname: %s\n",
> pkt_dev->nfrags, (unsigned long long) pkt_dev->delay,
> @@ -792,6 +814,61 @@ static int strn_len(const char __user * user_buffer, unsigned int maxlen)
> return i;
> }
>
> +static ssize_t get_imix_entries(const char __user *buffer,
> + struct pktgen_dev *pkt_dev)
> +{
> + /* Parses imix entries from user buffer.
> + * The user buffer should consist of imix entries separated by spaces
> + * where each entry consists of size and weight delimited by commas.
> + * "size1,weight_1 size2,weight_2 ... size_n,weight_n" for example.
> + */
This comments belongs before the function.
> + long len;
> + char c;
> + int i = 0;
> + const int max_digits = 10;
Please order these lines longest to shortest (reverse xmas tree).
> + pkt_dev->n_imix_entries = 0;
> +
> + do {
> + unsigned long size;
> + unsigned long weight;
same
> +
> + len = num_arg(&buffer[i], max_digits, &size);
> + if (len < 0)
> + return len;
> + i += len;
> + if (get_user(c, &buffer[i]))
> + return -EFAULT;
> + /* Check for comma between size_i and weight_i */
> + if (c != ',')
> + return -EINVAL;
> + i++;
> +
> + if (size < 14 + 20 + 8)
> + size = 14 + 20 + 8;
Why overwrite instead of rejecting?
> + len = num_arg(&buffer[i], max_digits, &weight);
> + if (len < 0)
> + return len;
> + if (weight <= 0)
> + return -EINVAL;
> +
> + pkt_dev->imix_entries[pkt_dev->n_imix_entries].size = size;
> + pkt_dev->imix_entries[pkt_dev->n_imix_entries].weight = weight;
> +
> + i += len;
> + if (get_user(c, &buffer[i]))
> + return -EFAULT;
What if this is the last entry?
> + i++;
> + pkt_dev->n_imix_entries++;
> +
> + if (pkt_dev->n_imix_entries > MAX_IMIX_ENTRIES)
> + return -E2BIG;
> + } while (c == ' ');
empty line here
> + return i;
> +}
> +
> static ssize_t get_labels(const char __user *buffer, struct pktgen_dev *pkt_dev)
> {
> unsigned int n = 0;
> @@ -960,6 +1037,18 @@ static ssize_t pktgen_if_write(struct file *file,
> return count;
> }
>
> + if (!strcmp(name, "imix_weights")) {
> + if (pkt_dev->clone_skb > 0)
> + return -ENOTSUPP;
ENOTSUPP should not be returned to user space, please use a different
one.
> + len = get_imix_entries(&user_buffer[i], pkt_dev);
> + if (len < 0)
> + return len;
> +
> + i += len;
> + return count;
> + }
> +
> if (!strcmp(name, "debug")) {
> len = num_arg(&user_buffer[i], 10, &value);
> if (len < 0)
> @@ -1082,10 +1171,16 @@ static ssize_t pktgen_if_write(struct file *file,
> len = num_arg(&user_buffer[i], 10, &value);
> if (len < 0)
> return len;
> + /* clone_skb is not supported for netif_receive xmit_mode and
> + * IMIX mode.
> + */
> if ((value > 0) &&
> ((pkt_dev->xmit_mode == M_NETIF_RECEIVE) ||
> !(pkt_dev->odev->priv_flags & IFF_TX_SKB_SHARING)))
> return -ENOTSUPP;
> + if (value > 0 && pkt_dev->n_imix_entries > 0)
> + return -ENOTSUPP;
ditto
> i += len;
> pkt_dev->clone_skb = value;
>
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