From: "Winkler, Tomas" <tomas.winkler@intel.com>
To: Richard Weinberger <richard@nod.at>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-mtd <linux-mtd@lists.infradead.org>,
Vignesh Raghavendra <vigneshr@ti.com>,
Miquel Raynal <miquel.raynal@bootlin.com>
Subject: RE: [PATCH] mtd: use refcount to prevent corruption
Date: Thu, 28 Jan 2021 06:33:47 +0000 [thread overview]
Message-ID: <a6cb6eb10bbb48989d3a9e087951e50e@intel.com> (raw)
In-Reply-To: <1776363776.325713.1611782270873.JavaMail.zimbra@nod.at>
>
> ----- Ursprüngliche Mail -----
> >> > When underlying device is removed mtd core will crash in case user
> >> > space is still holding an open handle to a mtd device node.
> >> > A proper refcounting is needed so device is release only when a
> >> > partition has no active users. The current simple counter is not
> >> > sufficient.
> >>
> >> Can you please explain a little more what devices are involved?
> >> Does it implement _get_device() and _put_device()?
> > No this is not connected to those handlers of the underlying device
> > and those won't help.
> > I have a spi device provided by MFD framework so it can go away anytime.
>
> Can it go away physically or just in software?
Software, but since this is mfd it's basically hotplug. The kernel is crashing when I simulate hardware failure.
>
> Usually the pattern is that you make sure in the device driver that nobody can
> orphan the MTD while it is in use.
> e.g. drivers/mtd/ubi/gluebi.c does so. In _get_device() it grabs a reference on
> the underlying UBI volume to make sure it cannot go away while the MTD (on
> top of UBI) is in use.
I can try that if it helps, because we are simulating possible lower level crash.
In an case I believe that the proper refcouting is much more robust solution, than the current one.
I'd appreciate if someone can review the actual implementation.
Thanks
Tomas
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http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2021-01-28 6:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 20:03 [PATCH] mtd: use refcount to prevent corruption Tomas Winkler
2021-01-27 20:46 ` Richard Weinberger
2021-01-27 20:55 ` Winkler, Tomas
2021-01-27 21:17 ` Richard Weinberger
2021-01-28 6:33 ` Winkler, Tomas [this message]
2021-01-28 7:47 ` Richard Weinberger
2021-01-28 8:53 ` Winkler, Tomas
2021-01-28 9:00 ` Miquel Raynal
2021-01-28 17:57 ` Winkler, Tomas
2021-01-28 20:23 ` Richard Weinberger
2021-01-29 16:12 ` Winkler, Tomas
2021-02-13 17:09 ` Winkler, Tomas
2021-02-15 13:43 ` Richard Weinberger
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