[dpdk-dev] [PATCH] app/testpmd: fix testpmd packets dump overlapping
Ferruh Yigit
ferruh.yigit at intel.com
Thu Nov 12 17:44:58 CET 2020
On 11/12/2020 8:36 AM, Jiawei Wang wrote:
> When testpmd enabled the verbosity for the received packets, if two packets
> was received at the same time, for example, sampling packet and normal
> packet, the dump output of these packets may be overlapping due to multiple
> core handled the multiple queues simultaneously.
>
Hi Jiawei,
Is the problem observer only when having sampling? Do you observe the problem
when multiple cores Rx?
> The patch uses one string buffer that collects all the packet dump output
> into this buffer and then printout it at last, that guarantee to printout
> separately the dump output per packet.
>
> Fixes: d862c45 ("app/testpmd: move dumping packets to a separate function")
>
> Signed-off-by: Jiawei Wang <jiaweiw at nvidia.com>
> ---
> app/test-pmd/util.c | 238 ++++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 177 insertions(+), 61 deletions(-)
>
> diff --git a/app/test-pmd/util.c b/app/test-pmd/util.c
> index 649bf8f..47b75b0 100644
> --- a/app/test-pmd/util.c
> +++ b/app/test-pmd/util.c
> @@ -12,15 +12,20 @@
> #include <rte_vxlan.h>
> #include <rte_ethdev.h>
> #include <rte_flow.h>
> +#include <rte_log.h>
>
> #include "testpmd.h"
>
> -static inline void
> -print_ether_addr(const char *what, const struct rte_ether_addr *eth_addr)
> +#define MAX_STRING_LEN 8192
> +
> +static inline int
> +print_ether_addr(const char *what, const struct rte_ether_addr *eth_addr,
> + char print_buf[], int buf_size)
> {
> char buf[RTE_ETHER_ADDR_FMT_SIZE];
> +
> rte_ether_format_addr(buf, RTE_ETHER_ADDR_FMT_SIZE, eth_addr);
> - printf("%s%s", what, buf);
> + return snprintf(print_buf, buf_size, "%s%s", what, buf);
> }
>
> static inline bool
> @@ -74,13 +79,18 @@
> uint32_t vx_vni;
> const char *reason;
> int dynf_index;
> + int buf_size = MAX_STRING_LEN * nb_pkts;
> + char print_buf[buf_size];
This is a large value to allocate from stack, specially with larger burst size.
Allocating from heap is an option but it has a cost.
So what do you think print per packet, instead of print per burst? This also
prevents display latency of the packet log.
> + int cur_len = 0;
>
> + memset(print_buf, 0, sizeof(print_buf));
> if (!nb_pkts)
> return;
> - printf("port %u/queue %u: %s %u packets\n",
> - port_id, queue,
> - is_rx ? "received" : "sent",
> - (unsigned int) nb_pkts);
> + cur_len += snprintf(print_buf + cur_len, buf_size - cur_len,
> + "port %u/queue %u: %s %u packets\n",
> + port_id, queue,
> + is_rx ? "received" : "sent",
> + (unsigned int) nb_pkts);
> for (i = 0; i < nb_pkts; i++) {
> int ret;
> struct rte_flow_error error;
> @@ -93,95 +103,183 @@
> is_encapsulation = RTE_ETH_IS_TUNNEL_PKT(packet_type);
> ret = rte_flow_get_restore_info(port_id, mb, &info, &error);
> if (!ret) {
> - printf("restore info:");
> + cur_len += snprintf(print_buf + cur_len,
> + buf_size - cur_len,
> + "restore info:");
This is not safe.
'snprintf' returns size of the required buffer size, not written chars, this can
make "buf_size - cur_len" a negative value at some point, and since 'size' type
is unsigned negative value will be converted into a very large number and this
will corrupt the stack.
<...>
> + if (cur_len >= buf_size)
> + TESTPMD_LOG(ERR, "no enough buffer (size: %d) to store "
> + "the current dump output (size: %d)\n",
> + buf_size, cur_len);
Instead of this error log, which I believe not very useful, why not append some
chars at the end of the actual buffer to say it is truncated, something like
if (truncated)
TESTPMD_LOG(INFO, "%s ...", print_buf);
else
TESTPMD_LOG(INFO, "%s", print_buf);
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