[PATCH v3] app/testpmd: fix VLAN header parsing

[Morten Brørup]

> From: Raslan Darawsheh [mailto:rasland at nvidia.com]
> Sent: Monday, 24 March 2025 10.34
> 
> When processing VLAN or QinQ packets, an infinite loop occurred,
> preventing the csum forward engine from proceeding and causing
> testpmd to hang during shutdown attempts.
> 
> Updated the `get_ethertype_by_ptype` function to correctly parse
> VLAN headers.
> 
> Fixes: 76730c7b9b5a ("app/testpmd: use packet type parsing API")
> Cc: haijie1 at huawei.com
> 
> Signed-off-by: Raslan Darawsheh <rasland at nvidia.com>
> ---
> v3: fixed wrong indentation
>     add boundaries check for 8 VLANs at max
> 
> v2: update commit log
>     fixed pointer handling to actually move the pointer
> ---
>  app/test-pmd/csumonly.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
> index 5b906eaa53..710967ca4d 100644
> --- a/app/test-pmd/csumonly.c
> +++ b/app/test-pmd/csumonly.c
> @@ -59,6 +59,8 @@
>  #define GRE_SUPPORTED_FIELDS	(GRE_CHECKSUM_PRESENT | GRE_KEY_PRESENT
> |\
>  				 GRE_SEQUENCE_PRESENT)
> 
> +#define MAX_VLAN_HEADERS 8
> +
>  /* We cannot use rte_cpu_to_be_16() on a constant in a switch/case */
>  #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
>  #define _htons(x) ((uint16_t)((((x) & 0x00ffU) << 8) | (((x) &
> 0xff00U) >> 8)))
> @@ -466,9 +468,10 @@ pkts_ip_csum_recalc(struct rte_mbuf **pkts_burst,
> const uint16_t nb_pkts, uint64
>  static uint32_t
>  get_ethertype_by_ptype(struct rte_ether_hdr *eth_hdr, uint32_t ptype)
>  {
> -	struct rte_vlan_hdr *vlan_hdr;
> +	struct rte_vlan_hdr *vlan_hdr, *max_vlans;
>  	uint16_t ethertype;
> 
> +

Please omit adding an extra empty line.

>  	switch (ptype) {
>  	case RTE_PTYPE_L3_IPV4:
>  	case RTE_PTYPE_L3_IPV4_EXT:
> @@ -486,10 +489,13 @@ get_ethertype_by_ptype(struct rte_ether_hdr
> *eth_hdr, uint32_t ptype)
>  		return _htons(RTE_ETHER_TYPE_IPV6);
>  	default:
>  		ethertype = eth_hdr->ether_type;
> -		while (eth_hdr->ether_type == _htons(RTE_ETHER_TYPE_VLAN)
> ||
> -			eth_hdr->ether_type == _htons(RTE_ETHER_TYPE_QINQ)) {
> -			vlan_hdr = (struct rte_vlan_hdr *)
> -				((char *)eth_hdr + sizeof(*eth_hdr));
> +		vlan_hdr = (struct rte_vlan_hdr *) RTE_PTR_ADD(eth_hdr,
> +					offsetof(struct rte_ether_hdr,
> ether_type));

Above line indentation with 2, not 3 TABs.

> +		max_vlans = vlan_hdr + MAX_VLAN_HEADERS;
> +		while (((ethertype == _htons(RTE_ETHER_TYPE_VLAN) ||

Superfluous parenthesis: "while ( ((x || y)) && z)".

> +			ethertype == _htons(RTE_ETHER_TYPE_QINQ))) &&
> +			vlan_hdr < max_vlans) {

Above two lines indentation with 2, not 1 TAB.

> +			vlan_hdr++;
>  			ethertype = vlan_hdr->eth_proto;
>  		}
>  		return ethertype;
> --
> 2.39.5 (Apple Git-154)

With above nits fixed (can be fixed when merging),
Reviewed-by: Morten Brørup <mb at smartsharesystems.com>