linux-kernel - Re: [PATCH] devcoredump: increase the device delete timeout to 10 mins

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Date:   Tue, 08 Feb 2022 22:12:41 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     Abhinav Kumar <quic_abhinavk@...cinc.com>,
        linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, rafael@...nel.org, robdclark@...il.com,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, seanpaul@...omium.org,
        swboyd@...omium.org, nganji@...eaurora.org,
        aravindh@...eaurora.org, khsieh@...eaurora.org, daniel@...ll.ch,
        dmitry.baryshkov@...aro.org
Subject: Re: [PATCH] devcoredump: increase the device delete timeout to 10
 mins

On Tue, 2022-02-08 at 13:04 -0800, Abhinav Kumar wrote:
> 
> It opened the file rightaway but could not finish reading.
> 
> The device gets deleted so the corresponding /data will disappear too ( 
> as the data node is under devcd*/data)

Yeah but even if the file disappears, the open file descriptor is still
there, no? Does sysfs somehow make those disappear? I know debugfs does
(now, to some extent, it didn't always), but I thought sysfs was
refcounting things and didn't do that?

What did the userspace actually see? read() returned 0 so EOF?

(I guess I could test it, but it's getting late)

Your other questions are related - you need to consider the file in
sysfs and the open file descriptor separately.

johannes