linux-kernel - Re: [RFC PATCH v2 1/2] af_vsock: SOCK

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Date:   Wed, 16 Mar 2022 11:35:47 +0000
From:   Krasnov Arseniy Vladimirovich <AVKrasnov@...rdevices.ru>
To:     Stefano Garzarella <sgarzare@...hat.com>
CC:     Rokosov Dmitry Dmitrievich <DDRokosov@...rdevices.ru>,
        Krasnov Arseniy <oxffffaa@...il.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2 1/2] af_vsock: SOCK_SEQPACKET receive timeout test

On 16.03.2022 11:51, Stefano Garzarella wrote:
> On Wed, Mar 16, 2022 at 07:27:45AM +0000, Krasnov Arseniy Vladimirovich wrote:
>> Test for receive timeout check: connection is established,
>> receiver sets timeout, but sender does nothing. Receiver's
>> 'read()' call must return EAGAIN.
>>
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
>> ---
>> v1 -> v2:
>> 1) Check amount of time spent in 'read()'.
> 
> The patch looks correct to me, but since it's an RFC and you have to send another version anyway, here are some minor suggestions :-)
> 

Ok, i'll prepare next version with fixes :)

>>
>> tools/testing/vsock/vsock_test.c | 79 ++++++++++++++++++++++++++++++++
>> 1 file changed, 79 insertions(+)
>>
>> diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
>> index 2a3638c0a008..6d7648cce5aa 100644
>> --- a/tools/testing/vsock/vsock_test.c
>> +++ b/tools/testing/vsock/vsock_test.c
>> @@ -16,6 +16,7 @@
>> #include <linux/kernel.h>
>> #include <sys/types.h>
>> #include <sys/socket.h>
>> +#include <time.h>
>>
>> #include "timeout.h"
>> #include "control.h"
>> @@ -391,6 +392,79 @@ static void test_seqpacket_msg_trunc_server(const struct test_opts *opts)
>>     close(fd);
>> }
>>
>> +static time_t current_nsec(void)
>> +{
>> +    struct timespec ts;
>> +
>> +    if (clock_gettime(CLOCK_REALTIME, &ts)) {
>> +        perror("clock_gettime(3) failed");
>> +        exit(EXIT_FAILURE);
>> +    }
>> +
>> +    return (ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
>> +}
>> +
>> +#define RCVTIMEO_TIMEOUT_SEC 1
>> +#define READ_OVERHEAD_NSEC 250000000 /* 0.25 sec */
>> +
>> +static void test_seqpacket_timeout_client(const struct test_opts *opts)
>> +{
>> +    int fd;
>> +    struct timeval tv;
>> +    char dummy;
>> +    time_t read_enter_ns;
>> +    time_t read_overhead_ns;
>> +
>> +    fd = vsock_seqpacket_connect(opts->peer_cid, 1234);
>> +    if (fd < 0) {
>> +        perror("connect");
>> +        exit(EXIT_FAILURE);
>> +    }
>> +
>> +    tv.tv_sec = RCVTIMEO_TIMEOUT_SEC;
>> +    tv.tv_usec = 0;
>> +
>> +    if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (void *)&tv, sizeof(tv)) == -1) {
>> +        perror("setsockopt 'SO_RCVTIMEO'");
>> +        exit(EXIT_FAILURE);
>> +    }
>> +
>> +    read_enter_ns = current_nsec();
>> +
>> +    if ((read(fd, &dummy, sizeof(dummy)) != -1) ||
>> +        (errno != EAGAIN)) {
> 
> Here we can split in 2 checks like in patch 2, since if read() return value is >= 0, errno is not set.
> 
>> +        perror("EAGAIN expected");
>> +        exit(EXIT_FAILURE);
>> +    }
>> +
>> +    read_overhead_ns = current_nsec() - read_enter_ns -
>> +            1000000000ULL * RCVTIMEO_TIMEOUT_SEC;
>> +
>> +    if (read_overhead_ns > READ_OVERHEAD_NSEC) {
>> +        fprintf(stderr,
>> +            "too much time in read(2) with SO_RCVTIMEO: %lu ns\n",
>> +            read_overhead_ns);
> 
> What about printing also the expected overhead?
> 
>> +        exit(EXIT_FAILURE);
>> +    }
>> +
>> +    control_writeln("WAITDONE");
>> +    close(fd);
>> +}
>> +
>> +static void test_seqpacket_timeout_server(const struct test_opts *opts)
>> +{
>> +    int fd;
>> +
>> +    fd = vsock_seqpacket_accept(VMADDR_CID_ANY, 1234, NULL);
>> +    if (fd < 0) {
>> +        perror("accept");
>> +        exit(EXIT_FAILURE);
>> +    }
>> +
>> +    control_expectln("WAITDONE");
>> +    close(fd);
>> +}
>> +
>> static struct test_case test_cases[] = {
>>     {
>>         .name = "SOCK_STREAM connection reset",
>> @@ -431,6 +505,11 @@ static struct test_case test_cases[] = {
>>         .run_client = test_seqpacket_msg_trunc_client,
>>         .run_server = test_seqpacket_msg_trunc_server,
>>     },
>> +    {
>> +        .name = "SOCK_SEQPACKET timeout",
>> +        .run_client = test_seqpacket_timeout_client,
>> +        .run_server = test_seqpacket_timeout_server,
>> +    },
>>     {},
>> };
>>
>> -- 
>> 2.25.1
>