[PATCH RESEND] mtd:spi-nor: Fix an issue of releasing resources during read/write

[Michael Walle]

Hi,

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

Am 2021-04-01 09:34, schrieb Yicong Yang:
> From: Xiang Chen <chenxiang66 at 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 at hisilicon.com>
> Signed-off-by: Yicong Yang <yangyicong at hisilicon.com>

Reviewed-by: Michael Walle <michael at walle.cc>
Tested-by: Michael Walle <michael at 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