From: David Sterba <dsterba@suse.cz>
To: Anand Jain <anandsuveer@gmail.com>
Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 4/4] btrfs: sysfs, add devid/dev_state kobject and attribute
Date: Mon, 9 Dec 2019 19:31:49 +0100 [thread overview]
Message-ID: <20191209183149.GR2734@twin.jikos.cz> (raw)
In-Reply-To: <8bd3d9b9-11b1-4c9a-8b59-ccfe0c6d92c4@oracle.com>
On Mon, Dec 09, 2019 at 10:05:39PM +0800, Anand Jain wrote:
> Looked into this further, actually we don't need any lock here
> the device delete thread which calls kobject_put() makes sure
> sysfs read is closed. So an existing sysfs read thread will have
> to complete before device free.
>
>
> CPU1 CPU2
>
> btrfs_rm_device
> open file
> btrfs_sysfs_rm_device_link
> call read, access freed device
> sysfs waits for the open file
> to close.
> btrfs_free_device
> kfree(device)
Ok, as long as this holds and sysfs file is removed before the device is
freed, the locking is not necessary.
next prev parent reply other threads:[~2019-12-09 18:31 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 11:27 [PATCH 0/4] btrfs, sysfs cleanup and add dev_state Anand Jain
2019-12-05 11:27 ` [PATCH 1/4] btrfs: sysfs, use btrfs_sysfs_remove_fsid in fail return in add_fsid Anand Jain
2019-12-05 11:27 ` [PATCH 2/4] btrfs: sysfs, add UUID/devinfo kobject Anand Jain
2020-01-14 18:32 ` David Sterba
2020-02-03 10:40 ` Anand Jain
2019-12-05 11:27 ` [PATCH v2 3/4] btrfs: sysfs, rename device_link add,remove functions Anand Jain
2019-12-05 11:27 ` [PATCH 4/4] btrfs: sysfs, add devid/dev_state kobject and attribute Anand Jain
2019-12-05 14:10 ` David Sterba
2019-12-05 14:38 ` Anand Jain
2019-12-05 14:21 ` David Sterba
2019-12-05 14:38 ` Anand Jain
2019-12-05 15:14 ` David Sterba
2019-12-06 13:49 ` Anand Jain
2019-12-09 14:05 ` Anand Jain
2019-12-09 18:31 ` David Sterba [this message]
2019-12-13 16:43 ` David Sterba
2019-12-13 17:02 ` David Sterba
2019-12-14 0:26 ` Anand Jain
2020-01-06 16:00 ` David Sterba
2019-12-09 14:06 ` [PATCH v2 " Anand Jain
2019-12-19 10:41 ` [PATCH v3 " Anand Jain
2020-01-06 11:38 ` [PATCH v4] " Anand Jain
2020-01-09 15:20 ` [PATCH v4 4/4] " David Sterba
2020-01-10 1:03 ` Anand Jain
2019-12-05 15:00 ` [PATCH 0/4] btrfs, sysfs cleanup and add dev_state David Sterba
2019-12-06 13:46 ` Anand Jain
2019-12-09 14:09 ` Anand Jain
2019-12-09 22:48 ` Anand Jain
2019-12-10 16:41 ` David Sterba
2020-01-14 18:39 ` David Sterba
2020-01-15 8:22 ` [PATCH] btrfs: update devid after replace Anand Jain
2020-01-15 16:17 ` David Sterba
2020-01-20 19:10 ` David Sterba
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