From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
Constantine Gavrilov <CONSTG@il.ibm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: io-uring <io-uring@vger.kernel.org>
Subject: Re: io_uring_enter() with opcode IORING_OP_RECV ignores MSG_WAITALL in msg_flags
Date: Wed, 23 Mar 2022 19:40:18 +0000 [thread overview]
Message-ID: <8f3cc170-1c24-da8a-37ec-f2e73eade46c@gmail.com> (raw)
In-Reply-To: <7e6f6467-6ac2-3926-9d7b-09f52f751481@kernel.dk>
On 3/23/22 12:19, Jens Axboe wrote:
> On 3/23/22 4:31 AM, Constantine Gavrilov wrote:
>> I get partial receives on TCP socket, even though I specify
>> MSG_WAITALL with IORING_OP_RECV opcode. Looking at tcpdump in
>> wireshark, I see entire reassambled packet (+4k), so it is not a
>> disconnect. The MTU is smaller than 4k.
>>
>> From the mailing list history, looks like this was discussed before
>> and it seems the fix was supposed to be in. Can someone clarify the
>> expected behavior?
>>
>> I do not think rsvmsg() has this issue.
>
> Do you have a test case? I added the io-uring list, that's the
> appropriate forum for this kind of discussion.
MSG_WAITALL (since Linux 2.2)
This flag requests that the operation block until the full
request is satisfied. However, the call may still return
less data than requested if a signal is caught
My guess would be that it's either due to signals (including
task_works actively used by io_uring) or because of some
interoperability problem with NOWAIT.
--
Pavel Begunkov
next prev parent reply other threads:[~2022-03-23 19:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <BYAPR15MB260078EC747F0F0183D1BB1BFA189@BYAPR15MB2600.namprd15.prod.outlook.com>
2022-03-23 12:19 ` io_uring_enter() with opcode IORING_OP_RECV ignores MSG_WAITALL in msg_flags Jens Axboe
2022-03-23 19:40 ` Pavel Begunkov [this message]
2022-03-23 12:11 Constantine Gavrilov
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