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From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>, [email protected]
Cc: [email protected], [email protected]
Subject: Re: [PATCH 1/2] io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly
Date: Wed, 23 Mar 2022 14:15:07 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 3/23/22 2:13 PM, Pavel Begunkov wrote:
> On 3/23/22 15:39, Jens Axboe wrote:
>> We currently don't attempt to get the full asked for length even if
>> MSG_WAITALL is set, if we get a partial receive. If we do see a partial
>> receive, then just note how many bytes we did and return -EAGAIN to
>> get it retried.
>>
>> The iov is advanced appropriately for the vector based case, and we
>> manually bump the buffer and remainder for the non-vector case.
> 
> How datagrams work with MSG_WAITALL? I highly doubt it coalesces 2+
> packets to satisfy the length requirement (e.g. because it may move
> the address back into the userspace). I'm mainly afraid about
> breaking io_uring users who are using the flag just to fail links
> when there is not enough data in a packet.

Yes was thinking that too, nothing is final yet.. Need to write a
SOCK_STREAM test case.

-- 
Jens Axboe


  reply	other threads:[~2022-03-23 20:15 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-23 15:39 [PATCHSET 0/2] Fix MSG_WAITALL for IORING_OP_RECV/RECVMSG Jens Axboe
2022-03-23 15:39 ` [PATCH 1/2] io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly Jens Axboe
2022-03-23 20:13   ` Pavel Begunkov
2022-03-23 20:15     ` Jens Axboe [this message]
2022-03-23 20:45     ` Constantine Gavrilov
2022-03-23 20:52       ` Pavel Begunkov
2022-03-23 21:24         ` Jens Axboe
2022-03-23 15:39 ` [PATCH 2/2] io_uring: add flag for disabling provided buffer recycling Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2022-03-23 22:41 [PATCHSET v2 0/2] Fix MSG_WAITALL for IORING_OP_RECV/RECVMSG Jens Axboe
2022-03-23 22:41 ` [PATCH 1/2] io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly Jens Axboe
2022-03-24  0:32   ` Stefan Metzmacher
2022-03-24  0:35     ` Jens Axboe

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