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Message-ID: <2262e5b6-d72b-42c3-8d49-663c910904ad@gmail.com>
Date: Tue, 7 May 2024 18:19:53 +0200
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Subject: Re: [PATCH net-next v8 3/3] selftests/net: add flush id selftests
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>, davem@davemloft.net,
 edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org,
 alobakin@pm.me, shuah@kernel.org, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
References: <20240506093550.128210-1-richardbgobert@gmail.com>
 <761374d3-1c76-4dc2-a4cc-7bd693deb453@gmail.com>
 <663912b7b9746_516de29445@willemb.c.googlers.com.notmuch>
From: Richard Gobert <richardbgobert@gmail.com>
In-Reply-To: <663912b7b9746_516de29445@willemb.c.googlers.com.notmuch>
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Willem de Bruijn wrote:
> Richard Gobert wrote:
>> Added flush id selftests to test different cases where DF flag is set or
>> unset and id value changes in the following packets. All cases where the
>> packets should coalesce or should not coalesce are tested.
>>
>> Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
>> ---
>>  tools/testing/selftests/net/gro.c | 147 ++++++++++++++++++++++++++++++
>>  1 file changed, 147 insertions(+)
>>
>> diff --git a/tools/testing/selftests/net/gro.c b/tools/testing/selftests/net/gro.c
>> index 353e1e867fbb..5dc7b539ccbf 100644
>> --- a/tools/testing/selftests/net/gro.c
>> +++ b/tools/testing/selftests/net/gro.c
>> @@ -617,6 +617,123 @@ static void add_ipv6_exthdr(void *buf, void *optpkt, __u8 exthdr_type, char *ext
>>  	iph->payload_len = htons(ntohs(iph->payload_len) + MIN_EXTHDR_SIZE);
>>  }
>>  
>> +static void fix_ip4_checksum(struct iphdr *iph)
>> +{
>> +	iph->check = 0;
>> +	iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
>> +}
>> +
>> +static void send_flush_id_case(int fd, struct sockaddr_ll *daddr, int tcase)
>> +{
>> +	static char buf1[MAX_HDR_LEN + PAYLOAD_LEN];
>> +	static char buf2[MAX_HDR_LEN + PAYLOAD_LEN];
>> +	static char buf3[MAX_HDR_LEN + PAYLOAD_LEN];
>> +	bool send_three = false;
>> +	struct iphdr *iph1;
>> +	struct iphdr *iph2;
>> +	struct iphdr *iph3;
>> +
>> +	iph1 = (struct iphdr *)(buf1 + ETH_HLEN);
>> +	iph2 = (struct iphdr *)(buf2 + ETH_HLEN);
>> +	iph3 = (struct iphdr *)(buf3 + ETH_HLEN);
>> +
>> +	create_packet(buf1, 0, 0, PAYLOAD_LEN, 0);
>> +	create_packet(buf2, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
>> +	create_packet(buf3, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
>> +
>> +	switch (tcase) {
>> +	case 0: /* DF=1, Incrementing - should coalesce */
>> +		iph1->frag_off |= htons(IP_DF);
>> +		iph1->id = htons(8);
>> +		fix_ip4_checksum(iph1);
>> +
>> +		iph2->frag_off |= htons(IP_DF);
>> +		iph2->id = htons(9);
>> +		fix_ip4_checksum(iph2);
>> +		break;
>> +
>> +	case 1: /* DF=1, Fixed - should coalesce */
>> +		iph1->frag_off |= htons(IP_DF);
>> +		iph1->id = htons(8);
>> +		fix_ip4_checksum(iph1);
>> +
>> +		iph2->frag_off |= htons(IP_DF);
>> +		iph2->id = htons(8);
>> +		fix_ip4_checksum(iph2);
>> +		break;
>> +
>> +	case 2: /* DF=0, Incrementing - should coalesce */
>> +		iph1->frag_off &= ~htons(IP_DF);
>> +		iph1->id = htons(8);
>> +		fix_ip4_checksum(iph1);
>> +
>> +		iph2->frag_off &= ~htons(IP_DF);
>> +		iph2->id = htons(9);
>> +		fix_ip4_checksum(iph2);
>> +		break;
>> +
>> +	case 3: /* DF=0, Fixed - should not coalesce */
>> +		iph1->frag_off &= ~htons(IP_DF);
>> +		iph1->id = htons(8);
>> +		fix_ip4_checksum(iph1);
>> +
>> +		iph2->frag_off &= ~htons(IP_DF);
>> +		iph2->id = htons(8);
>> +		fix_ip4_checksum(iph2);
>> +		break;
>> +
>> +	case 4: /* DF=1, two packets incrementing, and one fixed - should
>> +		 * coalesce only the first two packets
>> +		 */
>> +		iph1->frag_off |= htons(IP_DF);
>> +		iph1->id = htons(8);
>> +		fix_ip4_checksum(iph1);
>> +
>> +		iph2->frag_off |= htons(IP_DF);
>> +		iph2->id = htons(9);
>> +		fix_ip4_checksum(iph2);
>> +
>> +		iph3->frag_off |= htons(IP_DF);
>> +		iph3->id = htons(9);
>> +		fix_ip4_checksum(iph3);
>> +		send_three = true;
>> +		break;
>> +
>> +	case 5: /* DF=1, two packets fixed, and one incrementing - should
>> +		 * coalesce only the first two packets
>> +		 */
>> +		iph1->frag_off |= htons(IP_DF);
>> +		iph1->id = htons(8);
>> +		fix_ip4_checksum(iph1);
>> +
>> +		iph2->frag_off |= htons(IP_DF);
>> +		iph2->id = htons(8);
>> +		fix_ip4_checksum(iph2);
>> +
>> +		iph3->frag_off |= htons(IP_DF);
>> +		iph3->id = htons(9);
>> +		fix_ip4_checksum(iph3);
>> +		send_three = true;
>> +		break;
>> +	}
> 
> Consider moving the fix_ip4_checksum calls out of the switch to reduce
> duplication.
> 
>> +
>> +	write_packet(fd, buf1, total_hdr_len + PAYLOAD_LEN, daddr);
>> +	write_packet(fd, buf2, total_hdr_len + PAYLOAD_LEN, daddr);
>> +
>> +	if (send_three)
>> +		write_packet(fd, buf3, total_hdr_len + PAYLOAD_LEN, daddr);
>> +}
>> +
>> +static void test_flush_id(int fd, struct sockaddr_ll *daddr, char *fin_pkt)
>> +{
>> +	for (int i = 0; i < 6; i++) {
> 
> Please avoid unnamed magic constants. Something like
> 
> const int num_flush_id_cases = 6;	/* See switch in send_flush_id_case */
> 

Will do that, thanks for the review!

> Or even define an enum with named tests and and _MAX val. It's
> verbose, but helpful to readers.
> 
>> +		sleep(1);
>> +		send_flush_id_case(fd, daddr, i);
>> +		sleep(1);
>> +		write_packet(fd, fin_pkt, total_hdr_len, daddr);
>> +	}
>> +}
>> +