From mboxrd@z Thu Jan  1 00:00:00 1970
References: <f31cf9eb-1bbe-f4ea-cf7e-ba10f3969236@siemens.com>
From: Philippe Gerum <rpm@xenomai.org>
Subject: Re: "cobalt/vfile: seq_file seek index must progress"
In-reply-to: <f31cf9eb-1bbe-f4ea-cf7e-ba10f3969236@siemens.com>
Date: Fri, 21 May 2021 16:20:08 +0200
Message-ID: <8735ugdv8n.fsf@xenomai.org>
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Xenomai <xenomai@xenomai.org>


Jan Kiszka <jan.kiszka@siemens.com> writes:

> Hi Philippe,
>
> https://source.denx.de/Xenomai/xenomai/-/commit/dd9a5ee0ed6f734f40d3733f9fff23394c8647bd
>
> Bug fix unrelated to dovetail? There is no description, so I cannot
> easily asses this.
>

Yeah, not good. The idea is that the offset field we receive from the
kernel must progress in order for the loop to stop properly,
independently from our own tracking of the end-of-list condition.

AFAIR, this was very easily reproducible by running a test app creating
a few tenths of threads (10-20 would suffice) which would exit shortly
after, while running a cat loop on /proc/xenomai/sched/next. At some
point, the cat loop would cause the vfile handler to crash.

-- 
Philippe.