From: Alex Elder <elder@ieee.org>
To: Ilya Dryomov <idryomov@gmail.com>
Cc: Ceph Development <ceph-devel@vger.kernel.org>,
Varada Kari <Varada.Kari@sandisk.com>
Subject: Re: [PATCH 1/4] libceph: don't bail early from try_read() when skipping a message
Date: Sat, 20 Feb 2016 14:38:47 -0600 [thread overview]
Message-ID: <56C8CED6.7080701@ieee.org> (raw)
In-Reply-To: <CAOi1vP8V7Ni6G53Y-xhmuJihd=dmM6Fg6960CQZmLt451y5V5A@mail.gmail.com>
On 02/20/2016 02:21 PM, Ilya Dryomov wrote:
>> > So... There are two places in try_read_message() where
>> > incoming messages should be discarded, and they represent:
>> > receipt of a duplicate (re-sent) message; receipt of an
>> > unexpected message type; receipt of a response message
>> > that was not expected; or receipt of a response that was
>> > too large for the buffer that had been allocated to hold it.
> Just a note: it's less about the preallocated buffer being too small
> part (in theory we could allocate everything in alloc_msg(), although
> that would be stupid) and more about the "no outstanding request is
> waiting for that response" part. Stray and/or duplicate replies from
> the OSDs are expected in various cases.
Agreed. That one case (buffer too large) is anomalous. But
the code *does* say "skip the message" in that case, which
is why I mentioned it.
Like I said before, when it's been a while since I've reviewed
code I need to go immerse myself in it for a little while. And
while I'm at it, I figure I might as well explain it all for the
benefit of other people. This is especially true for these tiny
patches--sometimes the smaller the patch, the bigger the context
needed to understand why it fixes a problem.
-Alex
next prev parent reply other threads:[~2016-02-20 20:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-20 16:45 [PATCH 0/4] libceph: message skipping fixes Ilya Dryomov
2016-02-20 16:45 ` [PATCH 1/4] libceph: don't bail early from try_read() when skipping a message Ilya Dryomov
2016-02-20 18:28 ` Alex Elder
2016-02-20 20:21 ` Ilya Dryomov
2016-02-20 20:38 ` Alex Elder [this message]
2016-02-20 16:45 ` [PATCH 2/4] libceph: use the right footer size " Ilya Dryomov
2016-02-20 18:44 ` Alex Elder
2016-02-20 20:05 ` Ilya Dryomov
2016-02-20 20:15 ` Alex Elder
2016-02-21 14:31 ` Ilya Dryomov
2016-02-21 14:35 ` [PATCH 4/4] libceph: use sizeof_footer() more Ilya Dryomov
2016-02-21 15:08 ` Alex Elder
2016-02-20 16:45 ` [PATCH 3/4] libceph: don't spam dmesg with stray reply warnings Ilya Dryomov
2016-02-20 18:46 ` Alex Elder
2016-02-20 16:45 ` [PATCH 4/4] libceph: use sizeof_footer() in ceph_msg_revoke() Ilya Dryomov
2016-02-20 18:47 ` Alex Elder
2016-02-20 19:51 ` Ilya Dryomov
2016-02-20 19:56 ` Alex Elder
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