netdev - Re: [PATCH v2 net-next 02/14] net: Add a new socket option for a future transmit time.

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Message-ID: <3e97585b-f6a9-e15a-4d9f-3097704e591a@intel.com>
Date:   Mon, 9 Jul 2018 15:21:12 -0700
From:   Jesus Sanchez-Palencia <jesus.sanchez-palencia@...el.com>
To:     Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Cc:     tglx@...utronix.de, jan.altenberg@...utronix.de,
        vinicius.gomes@...el.com, kurt.kanzenbach@...utronix.de,
        henrik@...tad.us, richardcochran@...il.com,
        ilias.apalodimas@...aro.org, ivan.khoronzhuk@...aro.org,
        mlichvar@...hat.com, willemb@...gle.com, jhs@...atatu.com,
        xiyou.wangcong@...il.com, jiri@...nulli.us,
        jeffrey.t.kirsher@...el.com
Subject: Re: [PATCH v2 net-next 02/14] net: Add a new socket option for a
 future transmit time.



On 07/07/2018 05:44 PM, Eric Dumazet wrote:
> 
> 
> On 07/03/2018 03:42 PM, Jesus Sanchez-Palencia wrote:
>> From: Richard Cochran <rcochran@...utronix.de>
>>
>> This patch introduces SO_TXTIME. User space enables this option in
>> order to pass a desired future transmit time in a CMSG when calling
>> sendmsg(2). The argument to this socket option is a 8-bytes long struct
>> provided by the uapi header net_tstamp.h defined as:
>>
>> struct sock_txtime {
>> 	clockid_t 	clockid;
>> 	u32		flags;
>> };
>>
>> Note that new fields were added to struct sock by filling a 2-bytes
>> hole found in the struct. For that reason, neither the struct size or
>> number of cachelines were altered.
> 
> 
>> diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
>> index 4fe104b2411f..c9a77c353b98 100644
>> --- a/include/uapi/linux/net_tstamp.h
>> +++ b/include/uapi/linux/net_tstamp.h
>> @@ -141,4 +141,19 @@ struct scm_ts_pktinfo {
>>  	__u32 reserved[2];
>>  };
>>  
>> +/*
>> + * SO_TXTIME gets a struct sock_txtime with flags being an integer bit
>> + * field comprised of these values.
>> + */
>> +enum txtime_flags {
>> +	SOF_TXTIME_DEADLINE_MODE = (1 << 0),
>> +
>> +	SOF_TXTIME_FLAGS_MASK = (SOF_TXTIME_DEADLINE_MODE)
>> +};
>> +
>> +struct sock_txtime {
>> +	clockid_t       clockid;        /* reference clockid */
>> +	u32             flags;          /* flags defined by enum txtime_flags */
>> +};
>> +
> 
> I was under the impression that we could not use 'u32' type in include/uapi/linux/* file
> 
> This must be replaced by __u32, right ?


I'm sending a patch fixing that now, thanks.