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From: Michael Walle <michael@walle.cc>
To: Yicong Yang <yangyicong@hisilicon.com>
Cc: tudor.ambarus@microchip.com, p.yadav@ti.com,
	linux-mtd@lists.infradead.org, miquel.raynal@bootlin.com,
	richard@nod.at, vigneshr@ti.com, linuxarm@huawei.com,
	prime.zeng@huawei.com
Subject: Re: [PATCH RESEND] mtd:spi-nor: Fix an issue of releasing resources during read/write
Date: Wed, 07 Apr 2021 16:50:02 +0200	[thread overview]
Message-ID: <2f4b541e47046ee55728bca1a383033c@walle.cc> (raw)
In-Reply-To: <1617262486-4223-1-git-send-email-yangyicong@hisilicon.com>

Hi,

nit: subject should be "mtd: spi-nor: Fix.."

Am 2021-04-01 09:34, schrieb Yicong Yang:
> From: Xiang Chen <chenxiang66@hisilicon.com>
> 
> If rmmod the driver during read or write, the driver will release the
> resources which are used during read or write, so it is possible to
> refer to NULL pointer.
> 
> Use the testcase "mtd_debug read /dev/mtd0 0xc00000 0x400000 dest_file 
> &
> sleep 0.5;rmmod spi_hisi_sfc_v3xx.ko", the issue can be reproduced in
> hisi_sfc_v3xx driver.
> 
> To avoid the issue, fill the interface _get_device and _put_device of
> mtd_info to grab the reference to the spi controller driver module, so
> the request of rmmod the driver is rejected before read/write is 
> finished.
> 
> Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>

Reviewed-by: Michael Walle <michael@walle.cc>
Tested-by: Michael Walle <michael@walle.cc> [with spi-nxp-fspi and 
spi-fsl-dspi]

btw. you can also do:
lsmod
exec 3<> /dev/mtd0
lsmod

and have a look at the ref count.

-michael

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

  reply	other threads:[~2021-04-07 14:51 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01  7:34 [PATCH RESEND] mtd:spi-nor: Fix an issue of releasing resources during read/write Yicong Yang
2021-04-07 14:50 ` Michael Walle [this message]
2021-04-08 11:10   ` Yicong Yang
2021-04-09  3:21 ` Tudor.Ambarus
2021-04-09  4:03   ` Yicong Yang
2021-04-09  4:13     ` Tudor.Ambarus
2021-04-09  6:05       ` Yicong Yang
2021-04-11  7:45 ` Tudor Ambarus

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