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Date: Tue, 24 Jun 2014 21:41:17 +0100
From: Zoltan Kiss <zoltan.kiss@...rix.com>
To: Steffen Klassert <steffen.klassert@...unet.com>,
Mathias Krause <minipli@...glemail.com>,
Daniel Borkmann <dborkman@...hat.com>
CC: "David S. Miller" <davem@...emloft.net>,
Thomas Graf <tgraf@...g.ch>, Joe Perches <joe@...ches.com>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH net-next v2] pktgen: Fill the payload optionally with
a pattern
Sorry, I forgot the v2 from the subject
Zoltan
On 24/06/14 21:40, Zoltan Kiss wrote:
> Introduces a new flag called PATTERN, which puts a non-periodic, predicatble
> pattern into the payload. This was useful to reproduce an otherwise intermittent
> bug in xen-netback [1], where checksum checking doesn't help.
> The pattern is a repetition of " %lu", a series of increasing numbers divided by
> space. The value of the number is the size of the preceding payload area. E.g.
> " 1 3 5"..." 1000 1005 1010"
> If the pattern is used, every frag will have its own page, unlike before, so it
> needs more memory.
>
> [1] 5837574: xen-netback: Fix grant ref resolution in RX path
>
> Signed-off-by: Zoltan Kiss <zoltan.kiss@...rix.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Thomas Graf <tgraf@...g.ch>
> Cc: Joe Perches <joe@...ches.com>
> Cc: netdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: xen-devel@...ts.xenproject.org
> ---
> v2: some bugfixes for pattern_to_packet, as my upcoming patch revealed some
>
> net/core/pktgen.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 126 insertions(+), 13 deletions(-)
>
> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> index 0304f98..253b83d 100644
> --- a/net/core/pktgen.c
> +++ b/net/core/pktgen.c
> @@ -201,6 +201,7 @@
> #define F_QUEUE_MAP_CPU (1<<14) /* queue map mirrors smp_processor_id() */
> #define F_NODE (1<<15) /* Node memory alloc*/
> #define F_UDPCSUM (1<<16) /* Include UDP checksum */
> +#define F_PATTERN (1<<17) /* Fill the payload with a pattern */
>
> /* Thread control flag bits */
> #define T_STOP (1<<0) /* Stop run */
> @@ -255,7 +256,7 @@ struct pktgen_dev {
> int max_pkt_size;
> int pkt_overhead; /* overhead for MPLS, VLANs, IPSEC etc */
> int nfrags;
> - struct page *page;
> + struct page *pages[MAX_SKB_FRAGS];
> u64 delay; /* nano-seconds */
>
> __u64 count; /* Default No packets to send */
> @@ -1127,11 +1128,13 @@ static ssize_t pktgen_if_write(struct file *file,
> i += len;
>
> if (node_possible(value)) {
> + int j;
> pkt_dev->node = value;
> sprintf(pg_result, "OK: node=%d", pkt_dev->node);
> - if (pkt_dev->page) {
> - put_page(pkt_dev->page);
> - pkt_dev->page = NULL;
> + for (j = 0; j < MAX_SKB_FRAGS; ++j)
> + if (pkt_dev->pages[j]) {
> + put_page(pkt_dev->pages[j]);
> + pkt_dev->pages[j] = NULL;
> }
> }
> else
> @@ -1242,6 +1245,12 @@ static ssize_t pktgen_if_write(struct file *file,
> else if (strcmp(f, "!UDPCSUM") == 0)
> pkt_dev->flags &= ~F_UDPCSUM;
>
> + else if (strcmp(f, "PATTERN") == 0)
> + pkt_dev->flags |= F_PATTERN;
> +
> + else if (strcmp(f, "!PATTERN") == 0)
> + pkt_dev->flags &= ~F_PATTERN;
> +
> else {
> sprintf(pg_result,
> "Flag -:%s:- unknown\nAvailable flags, (prepend ! to un-set flag):\n%s",
> @@ -2623,17 +2632,98 @@ static inline __be16 build_tci(unsigned int id, unsigned int cfi,
> return htons(id | (cfi << 12) | (prio << 13));
> }
>
> +/* Max number of digits. The sizeof equals to log base 2^8 (UINT_MAX), multiply
> + * with 3 is a cheap, rounded up conversion to log10
> + */
> +#define UINT_MAX_DIGITS (3*sizeof(unsigned long)+1)
> +
> +/* Fill the buffer up with a pattern
> + * buf - pointer to buffer
> + * bufsize - size of the buffer
> + * start - starting value for the pattern
> + * incomplete - pointer to the offset inside the pattern, or 0 if none
> + *
> + * The pattern is a repetition of " %lu", a series of increasing numbers divided
> + * by space. The value of the number is "start" plus the size of the preceding
> + * space. E.g. if start is 1000, it starts like " 1000 1005 1010".
> + * If the last number doesn't fit, it gets truncated, and the number of leading
> + * characters is saved into incomplete. It can be passed then to the next call
> + * with the next buffer, and the pattern looks contiguous over scattered
> + * buffers.
> + * It returns "start" plus the offset of the byte after the last full
> + * pattern write.
> + */
> +static unsigned long pattern_to_packet(char *buf,
> + int bufsize,
> + unsigned long start,
> + unsigned int *incomplete)
> +{
> + int len;
> + /* Only used when the pattern doesn't align to the buffer */
> + char temp[UINT_MAX_DIGITS];
> +
> + if (*incomplete) {
> + int copylen, offset = *incomplete;
> +
> + len = snprintf(temp, sizeof(temp), " %lu", start);
> + copylen = len - *incomplete;
> + if (copylen > bufsize) {
> + /* The continuation of this number couldn't fit here */
> + copylen = bufsize;
> + *incomplete += bufsize;
> + } else {
> + *incomplete = 0;
> + start += len;
> + }
> + memcpy(buf, temp + offset, copylen);
> + bufsize -= copylen;
> + buf += copylen;
> + }
> +
> + while (bufsize > 0) {
> + len = snprintf(buf, bufsize, " %lu", start);
> + /* The last number doesn't fit, remember where it was truncated.
> + */
> + if (len >= bufsize) {
> + /* snprintf always add a trailing zero, but actually we
> + * need the last digit there
> + */
> + len = snprintf(temp, sizeof(temp), " %lu", start);
> + memcpy(buf, temp, bufsize);
> + /* If the last number just fit without the trailing
> + * zero, the next buffer can continue from an increased
> + * offset.
> + */
> + if (len == bufsize)
> + start += len;
> + *incomplete = bufsize;
> + return start;
> + }
> + bufsize -= len;
> + start += len;
> + buf += len;
> + }
> + return start;
> +}
> +
> static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb,
> int datalen)
> {
> struct timeval timestamp;
> struct pktgen_hdr *pgh;
> + unsigned long offset = 0;
> + unsigned int incomplete = 0;
>
> pgh = (struct pktgen_hdr *)skb_put(skb, sizeof(*pgh));
> datalen -= sizeof(*pgh);
>
> if (pkt_dev->nfrags <= 0) {
> - memset(skb_put(skb, datalen), 0, datalen);
> + if (pkt_dev->flags & F_PATTERN)
> + offset = pattern_to_packet(skb_put(skb, datalen),
> + datalen, offset,
> + &incomplete);
> + else
> + memset(skb_put(skb, datalen), 0, datalen);
> } else {
> int frags = pkt_dev->nfrags;
> int i, len;
> @@ -2644,7 +2734,12 @@ static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb,
> frags = MAX_SKB_FRAGS;
> len = datalen - frags * PAGE_SIZE;
> if (len > 0) {
> - memset(skb_put(skb, len), 0, len);
> + if (pkt_dev->flags & F_PATTERN)
> + offset = pattern_to_packet(skb_put(skb, len),
> + len, offset,
> + &incomplete);
> + else
> + memset(skb_put(skb, len), 0, len);
> datalen = frags * PAGE_SIZE;
> }
>
> @@ -2652,17 +2747,28 @@ static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb,
> frag_len = (datalen/frags) < PAGE_SIZE ?
> (datalen/frags) : PAGE_SIZE;
> while (datalen > 0) {
> - if (unlikely(!pkt_dev->page)) {
> + int fragpage;
> + gfp_t flags = GFP_KERNEL;
> +
> + if (pkt_dev->flags & F_PATTERN) {
> + fragpage = i;
> + } else {
> + fragpage = 0;
> + flags |= __GFP_ZERO;
> + }
> +
> + if (unlikely(!pkt_dev->pages[fragpage])) {
> int node = numa_node_id();
>
> if (pkt_dev->node >= 0 && (pkt_dev->flags & F_NODE))
> node = pkt_dev->node;
> - pkt_dev->page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
> - if (!pkt_dev->page)
> + pkt_dev->pages[fragpage] = alloc_pages_node(node, flags, 0);
> + if (!pkt_dev->pages[fragpage])
> break;
> }
> - get_page(pkt_dev->page);
> - skb_frag_set_page(skb, i, pkt_dev->page);
> + get_page(pkt_dev->pages[fragpage]);
> + skb_frag_set_page(skb, i, pkt_dev->pages[fragpage]);
> +
> skb_shinfo(skb)->frags[i].page_offset = 0;
> /*last fragment, fill rest of data*/
> if (i == (frags - 1))
> @@ -2671,6 +2777,10 @@ static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb,
> else
> skb_frag_size_set(&skb_shinfo(skb)->frags[i], frag_len);
> datalen -= skb_frag_size(&skb_shinfo(skb)->frags[i]);
> + if (pkt_dev->flags & F_PATTERN)
> + offset = pattern_to_packet(skb_frag_address(&skb_shinfo(skb)->frags[i]),
> + skb_frag_size(&skb_shinfo(skb)->frags[i]),
> + offset, &incomplete);
> skb->len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
> skb->data_len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
> i++;
> @@ -3685,6 +3795,8 @@ static void _rem_dev_from_if_list(struct pktgen_thread *t,
> static int pktgen_remove_device(struct pktgen_thread *t,
> struct pktgen_dev *pkt_dev)
> {
> + int i;
> +
> pr_debug("remove_device pkt_dev=%p\n", pkt_dev);
>
> if (pkt_dev->running) {
> @@ -3710,8 +3822,9 @@ static int pktgen_remove_device(struct pktgen_thread *t,
> free_SAs(pkt_dev);
> #endif
> vfree(pkt_dev->flows);
> - if (pkt_dev->page)
> - put_page(pkt_dev->page);
> + for (i = 0; i < MAX_SKB_FRAGS; ++i)
> + if (pkt_dev->pages[i])
> + put_page(pkt_dev->pages[i]);
> kfree(pkt_dev);
> return 0;
> }
--
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