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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: Wed, 27 Jan 2021 20:55:46 +0000	[thread overview]
Message-ID: <c8d0f22c5fdf443cb8dda1f996b148d9@intel.com> (raw)
In-Reply-To: <9732911.325628.1611780400338.JavaMail.zimbra@nod.at>


> Subject: Re: [PATCH] mtd: use refcount to prevent corruption
> 
> Tomas,
> 
> ----- Ursprüngliche Mail -----
> > Von: "Tomas Winkler" <tomas.winkler@intel.com>
> > An: "Miquel Raynal" <miquel.raynal@bootlin.com>, "richard"
> > <richard@nod.at>, "Vignesh Raghavendra" <vigneshr@ti.com>, "linux-mtd"
> > <linux-mtd@lists.infradead.org>, "linux-kernel"
> > <linux-kernel@vger.kernel.org>
> > CC: "Tomas Winkler" <tomas.winkler@intel.com>
> > Gesendet: Mittwoch, 27. Januar 2021 21:03:19
> > Betreff: [PATCH] mtd: use refcount to prevent corruption
> 
> > 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. 
My solution tries to  replace the current simple partition reference counting.  In previous solution it will return -EBUSY on partition that is held but will remove the actual parent device, leading to crash.
Also w/o reference counting there is no process to actually remove the partition that was previously busy.

Thanks
Tomas



> 
> Thanks,
> //richard
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

WARNING: multiple messages have this Message-ID (diff)
From: "Winkler, Tomas" <tomas.winkler@intel.com>
To: Richard Weinberger <richard@nod.at>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] mtd: use refcount to prevent corruption
Date: Wed, 27 Jan 2021 20:55:46 +0000	[thread overview]
Message-ID: <c8d0f22c5fdf443cb8dda1f996b148d9@intel.com> (raw)
In-Reply-To: <9732911.325628.1611780400338.JavaMail.zimbra@nod.at>


> Subject: Re: [PATCH] mtd: use refcount to prevent corruption
> 
> Tomas,
> 
> ----- Ursprüngliche Mail -----
> > Von: "Tomas Winkler" <tomas.winkler@intel.com>
> > An: "Miquel Raynal" <miquel.raynal@bootlin.com>, "richard"
> > <richard@nod.at>, "Vignesh Raghavendra" <vigneshr@ti.com>, "linux-mtd"
> > <linux-mtd@lists.infradead.org>, "linux-kernel"
> > <linux-kernel@vger.kernel.org>
> > CC: "Tomas Winkler" <tomas.winkler@intel.com>
> > Gesendet: Mittwoch, 27. Januar 2021 21:03:19
> > Betreff: [PATCH] mtd: use refcount to prevent corruption
> 
> > 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. 
My solution tries to  replace the current simple partition reference counting.  In previous solution it will return -EBUSY on partition that is held but will remove the actual parent device, leading to crash.
Also w/o reference counting there is no process to actually remove the partition that was previously busy.

Thanks
Tomas



> 
> Thanks,
> //richard

  reply	other threads:[~2021-01-27 20:56 UTC|newest]

Thread overview: 25+ 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 20:03 ` Tomas Winkler
2021-01-27 20:46 ` Richard Weinberger
2021-01-27 20:46   ` Richard Weinberger
2021-01-27 20:55   ` Winkler, Tomas [this message]
2021-01-27 20:55     ` Winkler, Tomas
2021-01-27 21:17     ` Richard Weinberger
2021-01-27 21:17       ` Richard Weinberger
2021-01-28  6:33       ` Winkler, Tomas
2021-01-28  6:33         ` Winkler, Tomas
2021-01-28  7:47         ` Richard Weinberger
2021-01-28  7:47           ` Richard Weinberger
2021-01-28  8:53           ` Winkler, Tomas
2021-01-28  8:53             ` Winkler, Tomas
2021-01-28  9:00             ` Miquel Raynal
2021-01-28  9:00               ` Miquel Raynal
2021-01-28 17:57               ` Winkler, Tomas
2021-01-28 17:57                 ` Winkler, Tomas
2021-01-28 20:23                 ` Richard Weinberger
2021-01-28 20:23                   ` Richard Weinberger
2021-01-29 16:12                   ` Winkler, Tomas
2021-02-13 17:09                   ` Winkler, Tomas
2021-02-13 17:09                     ` Winkler, Tomas
2021-02-15 13:43                     ` Richard Weinberger
2021-02-15 13:43                       ` Richard Weinberger

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