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Re: The dropped file
- From: David Smith <dsmith at redhat dot com>
- To: Mark Wielaard <mjw at redhat dot com>
- Cc: systemtap at sourceware dot org
- Date: Fri, 15 Jul 2011 09:50:19 -0500
- Subject: Re: The dropped file
- References: <1310730454.7351.7.camel@springer.wildebeest.org>
On 07/15/2011 06:47 AM, Mark Wielaard wrote:
> Hi,
>
> The relay_v2 transport creates a "dropped" file in the debugfs dir of
> the module. This file is created with mode 0444 and so is readable for
> everybody. That can at times lead to weird behavior since if somebody
> has that file open the module can no longer unload, leading to a
> successful script erroring out. Now this might not happen often, it was
> a weird script I was running that caused it, but it seems just creating
> the file with mode 0400 seems to work fine, and guards me from stupid
> scripts. So I am testing that, but don't fully understand what reads the
> dropped file on the other end. Anybody?
The user reads the dropped file to know how many messages the relay
system had to drop because all the buffer were full.
Since the user owns the dropped file, I don't see how changing the mode
to 400 will help you here (now I don't believe it could hurt either). I
guess it could keep others from keeping you from unloading your module.
--
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
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