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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: "Usyskin, Alexander" <alexander.usyskin@intel.com>
Cc: Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <tudor.ambarus@linaro.org>,
	Pratyush Yadav <pratyush@kernel.org>,
	"Michael Walle" <michael@walle.cc>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	"Winkler, Tomas" <tomas.winkler@intel.com>,
	Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Subject: Re: [PATCH v2] mtd: Fix refcounting with MTD_PARTITIONED_MASTER
Date: Fri, 4 Aug 2023 08:44:50 +0200	[thread overview]
Message-ID: <20230804084450.5b46aa8b@xps-13> (raw)
In-Reply-To: <CY5PR11MB63664273EC02BE1A9AC05D7EED0AA@CY5PR11MB6366.namprd11.prod.outlook.com>

Hi Alexander,

alexander.usyskin@intel.com wrote on Tue, 1 Aug 2023 08:45:47 +0000:

> Hi Miquel,
> 
> > -----Original Message-----
> > From: Miquel Raynal <miquel.raynal@bootlin.com>
> > Sent: Monday, July 31, 2023 12:09
> > To: Richard Weinberger <richard@nod.at>; Vignesh Raghavendra
> > <vigneshr@ti.com>; Tudor Ambarus <tudor.ambarus@linaro.org>; Pratyush
> > Yadav <pratyush@kernel.org>; Michael Walle <michael@walle.cc>; linux-
> > mtd@lists.infradead.org
> > Cc: Miquel Raynal <miquel.raynal@bootlin.com>; Winkler, Tomas
> > <tomas.winkler@intel.com>; Usyskin, Alexander
> > <alexander.usyskin@intel.com>; Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
> > Subject: [PATCH v2] mtd: Fix refcounting with MTD_PARTITIONED_MASTER
> > 
> > The logic is way too convoluted, let's clean the kref_get/put section to
> > clarify what this block does, hopefully solving the refcounting issue
> > when using CONFIG_MTD_PARTITIONED_MASTER at the same time:
> > - Iterate through all the parent mtd devices
> > - Grab a reference over them all but the master
> > - Only grab the master whith CONFIG_MTD_PARTITIONED_MASTER
> > Same logic must apply in the put path, otherwise it would be broken.
> > 
> > Cc: Tomas Winkler <tomas.winkler@intel.com>
> > Cc: Alexander Usyskin <alexander.usyskin@intel.com>
> > Cc: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
> > Fixes: 19bfa9ebebb5 ("mtd: use refcount to prevent corruption")
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> >   
> 
> I've put it on top of my "[PATCH v2] mtd: fix use-after-free in mtd release",
> looks ok, but I have had no problems with refcounting before...
> IMO, we need both this patch and my patch as they fix different issues.
> 
> Tested-by: Alexander Usyskin <alexander.usyskin@intel.com>
> 

Actually I don't think this patch fixes anything, besides the
simplification of the helpers which are (IMHO) more readable now.

Zhang, are you sure you test on the latest mtd/next branch? Because I
see no refcounting issue here, with/without PARTITIONED_MASTER.

Thanks,
Miquèl

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

  parent reply	other threads:[~2023-08-04  6:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-31  9:09 [PATCH v2] mtd: Fix refcounting with MTD_PARTITIONED_MASTER Miquel Raynal
2023-08-01  8:45 ` Usyskin, Alexander
2023-08-01  8:58   ` Miquel Raynal
2023-08-04  6:44   ` Miquel Raynal [this message]
2023-08-04  7:03 ` Miquel Raynal

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