From: Richard Cochran <richardcochran@gmail.com>
To: Vladis Dronov <vdronov@redhat.com>
Cc: linux-fsdevel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Al Viro <aviro@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] ptp: fix the race between the release of ptp_clock and cdev
Date: Fri, 27 Dec 2019 07:02:19 -0800 [thread overview]
Message-ID: <20191227150218.GA1435@localhost> (raw)
In-Reply-To: <20191227022627.24476-1-vdronov@redhat.com>
On Fri, Dec 27, 2019 at 03:26:27AM +0100, Vladis Dronov wrote:
> Here cdev is embedded in posix_clock which is embedded in ptp_clock.
> The race happens because ptp_clock's lifetime is controlled by two
> refcounts: kref and cdev.kobj in posix_clock. This is wrong.
>
> Make ptp_clock's sysfs device a parent of cdev with cdev_device_add()
> created especially for such cases. This way the parent device with its
> ptp_clock is not released until all references to the cdev are released.
> This adds a requirement that an initialized but not exposed struct
> device should be provided to posix_clock_register() by a caller instead
> of a simple dev_t.
>
> This approach was adopted from the commit 72139dfa2464 ("watchdog: Fix
> the race between the release of watchdog_core_data and cdev"). See
> details of the implementation in the commit 233ed09d7fda ("chardev: add
> helper function to register char devs with a struct device").
Thanks for digging into this!
Acked-by: Richard Cochran <richardcochran@gmail.com>
> /**
> * posix_clock_register() - register a new clock
> - * @clk: Pointer to the clock. Caller must provide 'ops' and 'release'
> - * @devid: Allocated device id
> + * @clk: Pointer to the clock. Caller must provide 'ops' field
> + * @dev: Pointer to the initialized device. Caller must provide
> + * 'release' filed
field
Thanks,
Richard
next prev parent reply other threads:[~2019-12-27 15:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 12:53 [PATCH] fs: fix use-after-free in __fput() when a chardev is removed but a file is still open Vladis Dronov
2019-12-08 19:49 ` Al Viro
2019-12-08 19:53 ` Al Viro
2019-12-27 2:26 ` [PATCH v2] ptp: fix the race between the release of ptp_clock and cdev Vladis Dronov
2019-12-27 15:02 ` Richard Cochran [this message]
2019-12-27 17:24 ` Vladis Dronov
2019-12-31 4:19 ` David Miller
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