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From:   "Bumwoo Lee" <bw365.lee@samsung.com>
To:     "'Chanwoo Choi'" <cwchoi00@gmail.com>,
        "'MyungJoo Ham'" <myungjoo.ham@samsung.com>,
        "'Chanwoo Choi'" <cw00.choi@samsung.com>,
        <linux-kernel@vger.kernel.org>
In-Reply-To: <67b840a9-c656-c871-afc1-84d2ec2c0fc3@gmail.com>
Subject: RE: [PATCH V1] extcon: modify extcon device to be created after
 driver data is set
Date:   Thu, 28 Apr 2022 09:36:36 +0900
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Hi Chanwoo,

Thank you for your kind detail guidance and example.

Best Regards,
Bumwoo Lee.
-----Original Message-----
From: Chanwoo Choi <cwchoi00=40gmail.com>=20
Sent: Thursday, April 28, 2022 8:16 AM
To: bumwoo lee <bw365.lee=40samsung.com>; MyungJoo Ham <myungjoo.ham=40sams=
ung.com>; Chanwoo Choi <cw00.choi=40samsung.com>; linux-kernel=40vger.kerne=
l.org
Subject: Re: =5BPATCH V1=5D extcon: modify extcon device to be created afte=
r driver data is set

Hi bumwoo,

On 22. 4. 27. 12:00, bumwoo lee wrote:
> Currently, someone can invoke the sysfs such as state_show()=20
> intermittently before dev_set_drvdata() is done.
> And it can be a cause of kernel Oops because of edev is Null at that time=
.
> So modified the driver registration to after setting drviver data.
>=20
> - Oops's backtrace.
>=20
> Backtrace:
> =5B<c067865c>=5D (state_show) from =5B<c05222e8>=5D (dev_attr_show)=20
> =5B<c05222c0>=5D (dev_attr_show) from =5B<c02c66e0>=5D (sysfs_kf_seq_show=
)=20
> =5B<c02c6648>=5D (sysfs_kf_seq_show) from =5B<c02c496c>=5D (kernfs_seq_sh=
ow)=20
> =5B<c02c4938>=5D (kernfs_seq_show) from =5B<c025e2a0>=5D (seq_read)=20
> =5B<c025e11c>=5D (seq_read) from =5B<c02c50a0>=5D (kernfs_fop_read)=20
> =5B<c02c5064>=5D (kernfs_fop_read) from =5B<c0231cac>=5D (__vfs_read)=20
> =5B<c0231c5c>=5D (__vfs_read) from =5B<c0231ee0>=5D (vfs_read) =5B<c0231e=
34>=5D=20
> (vfs_read) from =5B<c0232464>=5D (ksys_read) =5B<c02323f0>=5D (ksys_read)=
 from=20
> =5B<c02324fc>=5D (sys_read) =5B<c02324e4>=5D (sys_read) from =5B<c00091d0=
>=5D=20
> (__sys_trace_return)
>=20
> Signed-off-by: bumwoo lee <bw365.lee=40samsung.com>
> ---
>   drivers/extcon/extcon.c =7C 29 +++++++++++++++++------------
>   1 file changed, 17 insertions(+), 12 deletions(-)
(snip)

Applied it on extcon-fixes. Thanks for your work.
I change the first letter to capital letter as  following:
- extcon: Modify extcon device to be created after driver data is set


And better to use the correct version on patch title on next and then add t=
he changes according to version as following:
If you describe changes under '---', it is no problem when git apply with g=
it am command.

For example.
=5BPATCH v2=5D extcon: Modify extcon device to be created after driver data=
 ...

Signed-off-by: bumwoo lee <bw365.lee=40samsung.com>
---

Changes from v1:
- explain what are changes


--
Best Regards,
Samsung Electronics
Chanwoo Choi