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Date:      Wed, 18 Jan 2017 21:52:06 +0000
From:      Colin Percival <cperciva@tarsnap.com>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        freebsd-net@freebsd.org
Subject:   Re: sosend returning ERESTART
Message-ID:  <01000159b390c409-5adcb488-67e8-4038-b9b0-5d4f33460205-000000@email.amazonses.com>
In-Reply-To: <20170118103650.GE2349@kib.kiev.ua>
References:  <01000159aac969e6-b2fc3913-d04e-42d4-befd-402ed0d830bf-000000@email.amazonses.com> <20170117100634.GS2349@kib.kiev.ua> <01000159afddb7ce-064a5d17-4b81-4b2c-a9b4-3ddd2ad2e377-000000@email.amazonses.com> <20170118103650.GE2349@kib.kiev.ua>

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On 01/18/17 02:36, Konstantin Belousov wrote:
> On Wed, Jan 18, 2017 at 04:37:40AM +0000, Colin Percival wrote:
>> Thanks, looks like that was exactly it -- if the TCP send buffer was full
>> we would call sbwait, and if a signal arrived it would return ERESTART.
>> It looks like setting the SB_NOINTR flag will prevent this; I'm testing a
>> patch right now.
> 
> Note that passing SB_NOINTR unconditionally or even only for mounts
> with nointr (default) option is wrong. You make the socket operation
> uninterruptible, process terminate-ability becomes depended on the
> external factor, the behaviour of the remote system.

I'm not sure what you're getting at here.  The fact that "NFS mounted without
the intr flag" + "unresponsive NFS server" = "unkillable processes" has been
a (mis)feature of NFS for decades.

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid



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