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From: David Miller <davem@davemloft.net>
To: asmadeus@codewreck.org
Cc: doronrk@fb.com, tom@quantonium.net, davejwatson@fb.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] kcm: remove any offset before parsing messages
Date: Mon, 17 Sep 2018 18:45:02 -0700 (PDT)	[thread overview]
Message-ID: <20180917.184502.447385458615284933.davem@davemloft.net> (raw)
In-Reply-To: <20180912053642.GA2912@nautica>

From: Dominique Martinet <asmadeus@codewreck.org>
Date: Wed, 12 Sep 2018 07:36:42 +0200

> Dominique Martinet wrote on Tue, Sep 11, 2018:
>> Hmm, while trying to benchmark this, I sometimes got hangs in
>> kcm_wait_data() for the last packet somehow?
>> The sender program was done (exited (zombie) so I assumed the sender
>> socket flushed), but the receiver was in kcm_wait_data in kcm_recvmsg
>> indicating it parsed a header but there was no skb to peek at?
>> But the sock is locked so this shouldn't be racy...
>> 
>> I can get it fairly often with this patch and small messages with an
>> offset, but I think it's just because the pull changes some timing - I
>> can't hit it with just the clone, and I can hit it with a pull without
>> clone as well.... And I don't see how pulling a cloned skb can impact
>> the original socket, but I'm a bit fuzzy on this.
> 
> This is weird, I cannot reproduce at all without that pull, even if I
> add another delay there instead of the pull, so it's not just timing...

I really can't apply this patch until you resolve this.

It is weird, given your description, though...

  reply	other threads:[~2018-09-18  1:45 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-11  9:21 Dominique Martinet
2018-09-12  5:36 ` Dominique Martinet
2018-09-18  1:45   ` David Miller [this message]
2018-09-18  1:57     ` Dominique Martinet
2018-09-18  2:40       ` David Miller
2018-09-18  2:45         ` Dominique Martinet
2018-09-18  2:51           ` David Miller
2018-09-18  2:58             ` Dominique Martinet
2018-10-31  2:56       ` Dominique Martinet
2019-02-15  1:00         ` Dominique Martinet
2019-02-15  1:20           ` Tom Herbert
2019-02-15  1:57             ` Dominique Martinet
2019-02-15  2:48               ` Tom Herbert
2019-02-15  3:31                 ` Dominique Martinet
2019-02-15  4:01                   ` Tom Herbert
2019-02-15  4:52                     ` Dominique Martinet
2019-02-20  4:11                       ` Dominique Martinet
2019-02-20 16:18                         ` Tom Herbert
2019-02-21  8:22                           ` Dominique Martinet
2019-02-22 19:24                             ` Tom Herbert
2019-02-22 20:27                               ` Dominique Martinet
2019-02-22 21:01                                 ` Tom Herbert

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