From: Greg KH <gregkh@linuxfoundation.org>
To: Zhong Jinghua <zhongjinghua@huawei.com>
Cc: jejb@linux.ibm.com, martin.petersen@oracle.com, hare@suse.de,
bvanassche@acm.org, emilne@redhat.com,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
yi.zhang@huawei.com, yukuai3@huawei.com
Subject: Re: [PATCH-next v2 1/2] driver core: introduce get_device_unless_zero()
Date: Sat, 28 Jan 2023 11:43:20 +0100 [thread overview]
Message-ID: <Y9T8SION2vDlmaSa@kroah.com> (raw)
In-Reply-To: <20230128094146.205858-2-zhongjinghua@huawei.com>
On Sat, Jan 28, 2023 at 05:41:45PM +0800, Zhong Jinghua wrote:
> When the dev reference count is 0, calling get_device will go from 0 to 1,
You can NOT have a device reference count that is 0. If you do, you are
doing something really really wrong, and there's a bug somewhere else.
> which will cause errors in some place of the kernel.
It's already an error in the kernel that tries to increment a reference
count of 0 as that device is already freed and you are working with
memory that is not present.
> So introduce a
> get_devcie_unless_zero method that returns NULL when the dev reference
> count is 0.
No, this is not ok, sorry, please never do this. Fix the caller.
thanks,
greg k-h
next prev parent reply other threads:[~2023-01-28 10:43 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-28 9:41 [PATCH-next v2 0/2] scsi, driver core: fix iscsi rescan fails to create block device Zhong Jinghua
2023-01-28 9:41 ` [PATCH-next v2 1/2] driver core: introduce get_device_unless_zero() Zhong Jinghua
2023-01-28 10:43 ` Greg KH [this message]
2023-01-28 9:41 ` [PATCH-next v2 2/2] scsi: fix iscsi rescan fails to create block device Zhong Jinghua
2023-01-28 10:45 ` Greg KH
2023-01-29 1:13 ` Yu Kuai
2023-01-29 6:46 ` Greg KH
2023-01-29 6:55 ` Yu Kuai
2023-01-29 17:30 ` James Bottomley
2023-01-30 3:07 ` Yu Kuai
2023-01-30 3:29 ` James Bottomley
2023-01-30 3:46 ` Yu Kuai
2023-01-30 13:17 ` James Bottomley
2023-01-31 1:43 ` Yu Kuai
2023-01-31 3:25 ` James Bottomley
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